Đề tài nghiên cứu khoa học: Nghiên cứu, chế tạo, biến tính vật liệu hấp phụ hiệu năng cao zeolite sinh học phủ nano oxit kim loại và ứng dụng để xử lí các chất hữu cơ gây ô nhiễm môi trường nước

Tén dé tai: Nghiên cứu chế tạo, biến tính vật liệu hấp phụ hiệu năng cao zeolite sinh học phủ nano oxit kim loại và ứng dụng để xử lý các chất hữu cơ gây ô nhiễm môi trường nước 1.2.. Kế

ĐẠI HỌC QUÓC GIA HÀ NỘI

BAO CAO TONG KET

KET QUA THUC HIEN DE TAI KH&CN

CAP DAI HOC QUOC GIA

PHAN I THONG TIN CHUNG

1.1 Tén dé tai: Nghiên cứu chế tạo, biến tính vật liệu hấp phụ hiệu năng cao zeolite

sinh học phủ nano oxit kim loại và ứng dụng để xử lý các chất hữu cơ gây ô nhiễm

môi trường nước

1.2 Mã số: QG.22.17

1.3 Danh sách chủ trì, thành viên tham gia thực hiện đề tài

tài

TS Đặng Văn Long Khoa Hóa học, DH KHTN Chủ nhiệm đề tài

2 |Đoàn Thị Hải Yến Khoa Hóa học, ĐH KHTN|_ Thành viên đề tài

3_ [Phạm Tiến Đức Khoa Hóa học, BH KHTN|L Thành viên đề tài

4 Nguyễn Thị Minh Thư Khoa Hóa hoc, BH KHTN|L Thành viên đề tài

5 |HVCH Trương Thị Thùy Trang |Khoa Hóa hoc, DH KHTNL Thành viên đề tài

1.4 Đơn vị chủ trì: Trường Đại học Khoa học Tự nhiên

1.5 Thời gian thực hiện:

1.5.1 Theo hợp đồng: 24 tháng, từ tháng 5 năm 2022 đến tháng 5 năm 2024

1.5.2 Gia hạn (nếu có): Không

1.5.3 Thực hiện thực tế: 24 tháng, từ tháng 5 năm 2022 đến tháng 5 năm 2024

1.6 Những thay đổi so với thuyết minh ban dau:

- Thay đồi chủ nghiệm đề tai (theo quyết định số 1223/OD-PHOGHN ngày11/4/2023 của Giám đốc DHOGHN)

1.7 Tong kinh phi được phê duyệt của dé tài: 360 triệu đồng.

PHAN II TONG QUAN KET QUÁ NGHIÊN CỨU

1 Đặt vẫn đề

Xử lý ô nhiễm nguồn nước là một trong các vấn dé cấp thiết Các phương pháp

dé xử lý nguồn nước 6 nhiễm các hợp chất hữu co phổ biến hiện nay là kết tủa, trao

đổi ion, ozon hóa, lọc Tuy nhiên, hiệu quả xử lý của các phương pháp này khôngđược cao hay đòi hỏi yêu cầu kỹ thuật phức tạp va chi phí cao Gần đây, phương pháphấp phụ ngày càng trở lên phổ biến vì quá trình đơn giản, chi phí thấp và hiệu quả xử

ly ô nhiễm hữu cơ cao Việt Nam là một nước nông nghiệp, do đó lượng phế phụ phamnông nghiệp như lõi ngô, bã mía thải ra môi trường rất lớn Trong khi đó, chỉ một phần

phụ phẩm nông nghiệp được tái sử dụng hiệu quả Do đó, việc tận dụng các phụ phế

phẩm nông nghiệp dé tổng hợp các vật liệu hấp phụ hiệu năng cao là hướng di đúngđắn, bảo vệ môi trường Trong các ứng dụng hấp phụ, các lõi ngô, bã mía được hoạthóa làm tăng độ xốp hoặc dùng để chế tạo than sinh học hoặc than hoạt tính Tuynhiên, hiệu suất xử lý không được cao do các thuốc nhuộm trong nguồn nước và một

số chất diét cỏ có đặc tính phân cực mang điện tích khác nhau trong khi các loại than

hoạt tính hay than sinh học thường có bề mặt kị nước Các vật liệu mao quản được ứng

dụng rộng rãi trong hấp phụ Các zeolite với đặc tính cấu trúc là các lỗ xóp là vật liệuhấp phụ hữu cơ tiềm năng Với nghiên cứu được tiến hành trong đề tài này là tổng hợpvật liệu hấp phụ zeolite sẽ mang lại nhiều lượi thế như vật liệu diều chế dồi dào, rẻtiền, giải quyết khan hiếm vật liệu hấp phụ hiệu năng cao Tuy nhiên, các zeolite vimao quản còn nhiều hạn chế trong hấp phụ các phân tử kích thước lớn Với nghiên cứubiến tính bề mặt zeolite bằng các CHĐBM hay các polyme mang điện tích hay phủmột lượng nhỏ oxit đất hiếm nhẹ tăng cường tỉ trọng điện tích bề mặt và khả năng hấpphụ là một giải pháp hữu hiệu tiềm năng giải quyết được các nhược điểm trên

* Mục tiêu chung:

— Chế tạo được vật liệu zeolite sinh học từ các phụ phẩm nông nghiệp như bã mía, lõi

ngô , phủ oxit kim loại như CeO: dé tăng cường diện tích bề mặt

— Biến tính được bề mặt zeolite sinh học bằng phương pháp phủ chất hoạt động bề

mặt (CHĐBM) và các polyme mang điện tích nhằm tăng diện tích và điện tích bềmặt cua zeolite sinh học nói trên phục vụ cho mục tiêu hấp phụ xử lý thuốc nhuộm

và thuốc trừ cỏ trong môi trường nước

* Mục tiêu cụ thể:

- Ché tạo được vật liệu zeolite với thành phần pha SiO2 và Al2O3 khác nhau từ các

hóa chất tinh khiết

- Chế tạo được vật liệu zeolite sinh hoc từ các phụ phế phẩm nông nghiệp là vỏ trau

- _ Nghiên cứu động lực hoc hấp phụ của các hợp chất hữu cơ trên bề mặt zeolite

- Phủ oxit kim loại CeOa, biến tính bề mặt zeolite bằng phủ CHDBM, các polyme

mang điện tích đương và các polyme mang điện tích âm nhăm tăng cường tỉ trọngđiện tích bề mặt và tăng khả năng hấp phụ các chất ô nhiễm hữu cơ gây ô nhiễm

môi trường.

- _ Tiến hành xử lý các chất hữu co gây 6 nhiễm môi trường nước bao gồm các thuốc

nhuộm và chât diệt cỏ với hiệu suât xử lý cao trên 90%.

- Khảo sát đánh giá khả năng tái sử dụng của vật liệu hấp phụ

3 Phương pháp nghiên cứu

Phương pháp nghiên cứu, kỹ thuật sử dụng:

Các phương pháp điều chế vật liệu hấp phụPhương pháp thủy nhiệt dé điều chế vật liệu zeoliteZeolit thường được tổng hợp từ hỗn hợp dung dịch nước-kiềm của nhôm như nhômhydroxit, nhôm sunfat và silic như thủy tỉnh lỏng hay silicagel thưởng ở áp suấtthường hoặc trong autoclave ở áp suất cao Sự kết tinh của zeolite đòi hỏi khống

chê nghiêm ngặt nông độ các câu tử, sự hợp thức của các câu tử, nhiệt độ két tinh

và tốc độ khuấy các hỗn hợp sau khi trộn và tao gel, các tinh thé zeolite được tao

thành từ các hạt vô định hình thông qua sự chuyên pha gel sang pha lỏng

Phương pháp để điều chế zeolite từ các phế phâm nông nghiệp lõi ngô, bã míaCác phương pháp nghiên cứu cấu trúc, thành phần, đặc tính bề mặt của vật liệuPhương pháp nhiễu xạ Rơnghen (XRD): xác định cấu trúc, thành phần pha vậtliệu zeolite và vật liệu zeolite được phủ CeO: trên bề mặt

Phương pháp phổ hồng ngoại (IR): xác định các nhóm chức đặc trưng trên bềmặt vật liệu hấp phụ zeolite và zeolite biến tính

Phương pháp kính hién vi điện tử truyền qua (TEM): xác định hình thái và kíchthước hạt của zeolite và zeolite biến tính

Phương pháp BET: xác định diện tích bề mặt vật liệu zeolite và zeolite biến tínhPhương pháp do thé zeta: xác định điện tích cũng như độ linh động điện di củavật liệu zeolite và zeolite biến tính trong nền chất điện li

Các phương pháp phân tích định lượng nghiên cứu hấp phụPhương pháp phổ hấp phụ phân tử UV-Vis: xác định trực tiếp nồng độ thuốcnhuộm, chất diệt cỏ, CHĐBM và các polyme dương trong dung dịch

Phương pháp điện di mao quản với detector đo độ dẫn không tiếp xúc CD) và phương pháp sắc ký khí đo độ dẫn (GC-TCD) và sắc ký lỏng hiệu năngcao (HPLC) xác định nồng độ thuốc nhuộm, chất diệt cỏ, CHĐBM và các

(CE-polyme mang điện dương trong dung dịch.

Phương pháp đo tổng cacbon hữu cơ: dé xác định ham lượng thuốc nhuộm, chat

diét cỏ, CHDBM và các polymer mang điện dương.

Các phương pháp áp dụng các mô hình tính toán

Phương trình hấp phụ dang nhiệt cơ bản như Langmuir, Freundlich, mô hình

hấp phụ một bước hay hai bước.

- Phuong trình Ohshima trong tính toán, giải thích độ linh động điện di của các

hạt trong nền điện di khác nhau

- _ Các mô hình giả động học hấp phụ bậc 1 và bậc 2 góp phần đề xuất cơ chế hap

phụ.

Tính mới, tính độc đáo, tính sáng tạo của phương pháp, kỹ thuật sử dụng:

Thực tế, các phế phâm nông nghiệp như bã mía, lõi ngô thường được bỏ đimột cách lãng phí Do đó, nghiên cứu có tính độc đáo, hiệu quả cao khi điều chế vậtliệu hấp phụ hiệu năng cao tận dụng nguồn phế phẩm nông nghiệp Việc hấp phụ trựctiếp các chất ô nhiễm hữu cơ lên vật liệu thường không mang lại hiệu suất cao vì diệntích bề mặt nhỏ của zeolit Đây là nghiên cứu đầu tiên tại Việt Nam và là tiên phong

trên thé giới biến tính zeolite bằng CHDBM và các polyme mang điện tích, phủ CeO>

vào zeolite dé ứng dụng xử lý thuốc nhuộm va chất diệt cỏ trong môi trường nước

Quá trình biến tính và phủ CeO> có thé làm thay đổi và tăng cường tỉ trọng điện tích bềmặt vật liệu hấp phụ, có tính thực tiễn cao trong xử lý chất hữu cơ ô nhiễm môi trường

nước.

4 Tổng kết kết quả nghiên cứu

- Quy trình chế tao vật liệu Zeolite sinh học từ các phụ phế phâm nông nghiệp (vỏ

trau) được phủ CeOa Kết quả đã tổng hợp được 500 g vật liệu mẫu loại Zeolite sinh

hoc, phủ CeO» có diện tích bề mặt riêng 50 m”g; thé zeta 30 mV

- Vật liệu Zeolite sinh học biến tính với polymer mang điện tích dương có thế Zeta là

30 mV Kết quả đã tông hợp được 500 gam vật liệu mẫu loại Zeolite sinh học biến tínhvới polymer mang điện tích đương có thế Zeta 30 mV

- Vật liệu Zeolite sinh học biến tính với CHDBM mang điện tích dương có thế zeta là

30 mV Kết quả thù được là 500 gam vật liệu mẫu loại Zeolite sinh học biến tính với

CHĐBM (chất hoạt động bề mặt) mang điện tích dương có thé Zeta đạt trên 30 mV vàkèm theo các thông số xác định các đặc tính hóa lý và hóa học được xác định bằng các

phương pháp hiện đại: BET, XRD, XRE, SEM, TEM và FT-IR.

5 Đánh giá về các kết quả đã đạt được và kết luận

Đề tài đã nghiên cứu chế tạo được vật liệu Zeolite sinh học từ các phụ phẩmnông nghiệp (vỏ trau) bằng phương pháp thủy nhiệt ứng dụng trong hấp phụ xử lýthuốc nhuộm azo và thuốc trừ sâu glyphosate gây ô nhiễm môi trường nước Nghiêncứu chế tạo được vật liệu Zeolite phủ Cerioxit (CeO2) (CeO2@Zeolite) ứng dụng tronghấp phụ xử lý thuốc nhuộm azo và thuốc trừ sâu glyphosate gây ô nhiễm môi trường

nước.

Đã tổng hợp đưa ra được quy trình chế tạo vật liệu Zeolite sinh học từ các phụphế phẩm nông nghiệp (vỏ trau) được phủ CeOz có diện tích bề mặt riêng 50 m2/g

4

bang các phương pháp nhiễu xa tia Rơnghen (XRD), phương pháp phổ hồng ngoạibiến đổi Fourier (FT-IR), phương pháp kính hiển vi điện tử truyền qua, thuyết hấp phụBrunauer- Emmett- Teller (BET) xác định diện tích bề mặt và điện thế Zeta.

Đã tổng hợp đưa ra được quy trình chế tạo vật liệu Zeolite sinh học và Zeolitephủ CeOa có thé zeta 30 mV bang các phương pháp nhiễu xa tia Ronghen (XRD),phương pháp phô hồng ngoại biến đồi Fourier (FT-IR), phương pháp kính hién vi điện

tử truyền qua, thuyết hấp phụ Brunauer- Emmett- Teller (BET) xác định diện tích bềmặt và điện thế Zeta

6 Tóm tắt kết quả (tiếng Việt và tiếng Anh)

Tiếng Việt

Zeolit Permutit (Per) với tinh thé lập phương, tỷ lệ siO2/Al2O3 là 1,66, diện tích

bề mặt riêng là 44,81 m’/g, ban kinh 16 rong trung bình là 1,7 nm va các liên kết đặc

trưng của Si-OH, Si- O-Si, Si-O-Al và O-Si-O-Si đã được nghiên cứu trong nghiên cứu này.

Hiệu suất loại bỏ hấp phụ của thuốc nhuộm azo PC4R đã tăng gần gấp đôi từkhoảng 53,23% lên 90,06% nhờ sự thay đồi diện tích bề mặt Per với chất hoạt động bềmặt cation cetyltrimethylammonium bromide (CTAB) làm chất hấp phụ hiệu quả vàcho hiệu suất cao Quá trình loại bỏ chất hấp phụ PC4R được tối ưu hóa ở các giá trị

có độ pH=4, nồng độ NaCl 10 mM, tốc độ mỗi lần là 6 mg/mL và thời gian tiếp xúcngắn là 15 phút Cả hai mô hình Langmuir và Freundlich đều hợp lý để mô tả cácđường đăng nhiệt hap phụ PC4R trên CTAB@Per trong khi động học hap phụ hóa họcPC4R phù hợp tốt với mô hình giả bậc hai Khả năng hấp phụ đa lớp PC4R đạt cực đạingoại suy là 15,470 mg/g Các cơ chế hấp phụ PC4R đã được chứng minh bằng phép

đo FT-IR chủ yếu là lực hút tĩnh điện giữa CTAB va PC4R, tương tác lưỡng cuc-ion

và liên kết hydro giữa các phân tử PC4R

adsorbent The PC4R adsorptive removal was optimized at independent variables of

pH 4, the ionic strength of 10 mM NaCl, the Per dosage of 6 mg.mL— 1, and the short contact time of 15 min Both the Langmuir and Freundlich models were reasonable to describe the PC4R adsorption isotherms on the CTAB@Per while the PC4R

chemisorption kinetics were well accorded with the pseudo-second-order model The PC4R multilayer adsorption capacity achieved an extrapolated maxima of 15.470

mg.g— 1 The PC4R adsorption mechanisms were demonstrated by the FT-IR

measurement to be primarily the electrostatic attractions between the CTAB and the PC4R, dipole-ion interactions, and hydrogen bondings between the PC4R molecules.

PHAN III SAN PHAM, CONG BO VA KET QUA DAO TAO CUA DE TAI

3.1 Kết quả nghiên cứu

Yêu cầu khoa học hoặc/và chỉ tiêu kinh tế

TT Tên sản phẩm - kỹ thuật

Đăng ký Đạt được

Quy trình chế tạo vật liệu

1 |Quy trình chế tạo vật liệu| Diện tích bề mặt Diện tích bề mặt

Zeolite sinh học từ các phụ phê riêng tôi thiêu 50 riêng tôi thiêu 50

phâm nông nghiệp (bã mia, lõi m”/g m”/g

gô, ) được phủ CeO2

2 | Vật liệu Zeolite sinh hoc va) Thế zeta tối thiểu 30 | Thế zeta tối thiểu

Zeolite phủ CeO2 mV 30 mV

3 | Vat liệu Zeolite sinh học biên | Thế zeta tối thiểu 30 | Thế zeta tối thiểu

tính với polymer mang điện tích mV 30 mV

dương có thé Zeta tối thiểu 30 mV

4 | Vật liệu Zeolite sinh học biển | Thế zeta tối thiểu 30 | Thế zeta tối thiểu

tính với CHĐBM mang điện tích mV 30 mV

dương có thé zeta tối thiểu 30

mV

San pham vật liệu mau

5 |500 gam vật liệu mau loai| Thế zeta tối thiểu 30 | Thế zeta tối thiểu

Zeolite sinh học, phủ CeO2 mV 30 mV

6 |500 gam vật liệu mau loại | Thế zeta tối thiểu 30 | Thế zeta tối thiểu

Zeolite sinh học biên tính với mV 30 mV polymer mang điện tích dương

có thế Zeta tối thiểu 30 mV

Yêu cầu khoa học hoặc/và chỉ tiêu kinh tế

TT Tên sản phẩm - kỹ thuật

Đăng ký Đạt được

7 |500 gam vật liệu mẫu loại | Thế zeta tối thiểu 30 | Thế zeta tối thiểu

Zeolite sinh học biên tính với mV 30 mV

CHĐBM (chat hoạt động bê mặt) mang điện tích dương có

thê Zeta tôi thiêu 30 mV và kèm

theo các thông sô xác định các

đặc tính hóa lý và hóa học được xác định băng các phương pháp hiện dai: BET, XRD, XRF,

SEM, TEM va FT-IR.

3.2 Hình thức, cấp độ công bố kết quả

Tình trạng | Ghi địa | Đánh

(Đã in/ chấp chỉ và giá nhận in/ đã cảmơn | chun nộp don/ da | SW tài trợ |g

: 2 duoc chap cua (Đại,

“7 San pham nhận don hợp DHQGH khôn

lé/ đã được | Ning | g dat) cap gidy xdc quy định

nhận SHT T7 xác nhận sử

dụng sản

phẩm )

| Công trình công bố trên tạp chí khoa học quốc tế theo hệ thống ISI/Scopus

11 Thi Hai Yen Doan, Van Long Dang, Thi Đã in Có Đạt

Thuy Trang Truong, Thi Ngan Vu, Thanh Son Le, Thi Minh Thu Nguyen, Minh Ngoc Nguyen, Thu Thao Pham, Shin-ichi Yusa, Tien Duc Pham “Removal of Acid Orange G Azo Dye _ by

Modified Alpha Alumina Nanoparticles’.

Chem Asian J 2023, e202300404.

https://doi.org/10.1002/asia.202300404, ISI Q1.

Polycation-12 Van Long Dang, Thu Trang Kieu, Thi Da in Có Đạt

Thu Thao Nguyen, Thi Thuy Trang Truong,

Duy Thanh Hoang, Thi Linh Chi Vu, Thi

Minh Thu Nguyen, Thanh Son Le, Thi Hai Yen Doan, Tien Duc Pham “Surface

modification of zeolite by cationic surfactant and the application on adsorptive removal of azo dye Ponceau 4R” Journal of Molecular Structure 1304

(2024) 137619.

https://doi.org/10.1016/.molstruc.2024.1

37619 ISI Q2.

3.3 Két qua dao tao

¬ ¬ Công trình công bố liên

¬ ae gian bia kinh quan Đã bao

TT Họ và tên phí tham gia dé tài „ A

(số tháng/số tiền) (Sản pham KHCN, luận án, VỆ

luận văn)

Học viên cao học

1 | Trương Thị 3/24.957.500 Tên luận văn: Nghiên cứu | Đã có

Thùy Trang hấp phụ xử lý chất hữu cơ bang

khó phân hủy trên vật liệu nano oxit kim lọai được

biến tính bề mặt bằng

polyme mang điện.

PHAN IV TONG HỢP KET QUÁ CÁC SAN PHAM KH&CN VA ĐÀO TAO

PHẦN V TÌNH HÌNH SỬ DỤNG KINH PHÍ

Kinh phí được | Kinh phí thực

TT Nội dung chi duyệt hiện on

(triệu dong) (triệu dong)

A_ | Chi phí trực tiếp 342.000.000 342.000.000

1 | Thuê khoán chuyên môn 268.796.100 268.796.100

2 | Nguyên vật liệu, năng lượng 62.000.000 62.000.000

3 | Hội nghị, Hội thảo, kiêm tra tiến 10.800.000 10.800.000

- _ Nghiệm thu, thanh lý đề tài

PHAN VI PHU LUC (minh chứng các sản phẩm nêu ở Phan II)

Minh chứng kết quả đào tạo

- Minh chứng kết quả công bố

Minh chứng kết quả nghiên cứu

Đơn vị chủ trì đề tài(Thủ trưởng don vi ký tên, đóng dau)

Chủ nhiệm đề tài

TS Đặng Văn Long

PHỤ LỤC

(minh chứng các sản phẩm nêu ở Phan III)Phụ lục 1 Minh chứng kết quả đào tạo

01 Học viên cao học đã có bằngPhụ lục 2 Minh chứng kết quả công bố

02 bài báo công bố trên tạp chí khoa học quốc tế theo hệ thong ISIPhụ lục 3 Minh chứng kết quả nghiên cứu

3.1 Quy trình chế tạo vật liệu3.2 Sản phẩm vật liệu mẫu

Phụ lục 4 Thuyết minh dé tài

10

Phụ lục 1 Minh chứng kết quả đào tạo

Đào tạo 01 học viên cao học đã có bằng

11

ĐẠI HỌC QUOC GIA HÀ NỘI CỘNG HÒA XÃ HỘI CHỦ NGHĨA VIỆT NAM

TRƯỜNG ĐẠI HỌC KHOA HỌC TỰ NHIÊN Độc lập - Tự do - Hạnh phúc

BANG DIEM THAC SĨ

(Chỉ có giá trị kèm theo văn bằng số: QM 041244 cắp ngày 26/09/2023)

Họ và tên: Trương Thị Thùy Trang Ngày sinh: 10/10/1999 Nơi sinh: Hà Nội

Quyết định công nhận học viên cao học số 3485/QĐ-ĐHKHTN ngày 15/12/2021

của Hiệu trưởng Trường Đại học Khoa học Tự nhiên

Chuyên ngành: Hóa phân tích Mã số: 8440112.03

Quyết định công nhận hoc vị và cắp bằng thạc sĩ số 2751/QD-DHKHTN ngày 22/08/2023 của Hiệu trưởng

Trường Đại học Khoa học Tự nhiên

KET QUA HỌC TAP

Ma hoc ˆ à Số tín Mã học ˆ à

' Các kỹ thuật tách chất và

ENG5001 |Tiéng Anh cơ bản CHE6302 sắc ký trong phân tích 2 A

Các phương pháp hiện đại Các phương pháp phân

Các phương pháp phân Phương pháp tính Hóa

pass» tích quang phổ nâng cao ? A+ |CHE6002 lượng tử trong Hóa học 3

CHE6307 Các kỹ thuật phân tích CHE6306 Các kỹ thuật phân tích hiện

vết các chat

Trung binh chung hoc tap Tổng số tin chỉ tích lũy | |

Tên đề tài: Nghiên cứu hap phụ xử ly chất hữu cơ khó phân Hội đồng cham luận văn:

hủy trên vật liệu nano oxit kim loại được biến tính bề mặt bằng _ Chủ tich: PGS.TS Pham Thị Ngọc Mai

polyme mang điện Phản biện 1: PGS.TS Nguyễn Thị Ánh Hường

Người hướng dan khoa học: _ Phản biện 2: PGS.TS Nguyễn Xuân Trường

PGS.TS Phạm Tiên Đức; TS Đoàn Thị Hải Yên Thư ký: TS Hoàng Quốc Anh

Ngày bao Võ: 90/00/2026 Ủy vién: TS Nguyễn Vân Anh

Nơi bảo vệ: Trường Đại học Khoa học Tự nhiên - ĐHQGHN

Điểm luận văn: A+

ĐẠI HỌC QUÓC GIA HÀ NỘI CỘNG HOÀ XÃ HỘI CHỦ NGHĨA VIỆT NAM

TRƯỜNG ĐẠI HỌC KHOA HỌC TỰ NHIÊN Độc lập - Tự do - Hạnh phúc

Số: £048 /QD-DHKHTN

Ha Nội, ngày 20 thang € nam 2023

QUYET DINH

Vé việc thành lập Hội dong đánh giá luận văn thạc sĩ

HIỆU TRƯỞNG TRƯỜNG ĐẠI HỌC KHOA HỌC TỰ NHIÊN

Căn cứ Quy định về Tổ chức và hoạt động của các đơn vị thành viền và don vị trực

thuộc Đại học Quốc gia Hà Nội ban hành theo Quyết định số 3568/OD-PHOGHN ngày

08/10/2014 của Giám đốc Đại học Quốc gia Hà Nội;

Can cứ Quy chế đào tạo thạc si tại Dai học Quốc gia Hà Nội ban hành theo Quyết

định số 4668/OD-DHOGHN ngày 10/12/2014 của Giám đốc Đại học Quốc gia Hà Nội;

Căn cứ Quyết định số 250/QD-DHQGHN ngày 18/01/2018 của Giám đốc Đại học

Quốc gia Hà Nội về việc chuyển đổi các ngành, chuyên ngành đào tạo ở Đại học Quốc

gia Hà Nội theo Danh mục giáo duc, đào tạo cap IV trình độ đại học, thạc sĩ, tiễn sĩ;

Theo đề nghị của Trưởng khoa Hóa học và Trưởng phòng Đào tạo.

QUYÉT ĐỊNH:

Điều 1 Thành lập Hội đồng đánh giá luận văn của học viên Trương Thị Thùy Tra yors

Ngày sinh: 10/10/1999 Khóa: QH.2021.T.C = not

Chuyên ngành: Hóa phân tích Mã số: 8440112.03 cae

Đề tài: "Nghiên cứu hap phụ xử lý chất hữu cơ khó phân hủy trên vật liệu nan

kim loại được biến tính bê mặt bằng polyme mang điện"

Người hướng dẫn: PGS.TS Phạm Tiến Đức, TS Đoàn Thị Hải Yến

Điều 2 Ủy nhiệm Trưởng khoa Hóa học tổ chức bảo vệ luận văn trên theo quy định hiện

hành Hội đông tự giải thê sau khi hoàn thành nhiệm vụ.

Diều 3 Trưởng các đơn vị có liên quan, học viên Trương Thị Thùy Trang và các thành

viên trong Hội đồng đánh giá luận văn thạc sĩ chịu trách nhiệm thi hành Quyết định này./.

DANH SÁCH HỘI ĐÒNG ĐÁNH GIÁ LUẬN VĂN THẠC SĨ

(Kèm theo Quyết định số: ¿039/QĐ-ĐHKHTN, ngày 30/ 6 /2023)

Trách

Cơ quan công tác nhiệm trong; Ghichú |

Hội đồng Trường Đại học Khoa học "

STT Họ tên

1 |PGS.TS Pham Thị Ngọc Mai

IP@S.TS, Nguyễn Thị Ánh Trường Đại học Khoa học en ee

| 2 |Hường Ty nhién-DHQGHN | Phan biện l |

——— +

3 |PGS.TS Nguyễn Xuân Trường ee bọc Bách Khoa Ha | shan biter?

| : b

Trường Đại học Khoa học Thư ký

4 TS Hoàng Quôc Anh Tự nhiên - BHOGHN

Trường Đại học Thủ đô

5 là Nguyên Vân Anh Hà Nội Ủy viên

(Hội dong gom 05 thành viên.⁄) d4

_ ĐẠIHỌC QUÓC GIA HÀ NỘI CỘNG HOÀ XÃ HỘI CHỦ NGHĨA VIỆT NAM

TRƯỜNG ĐẠI HỌC KHOA HỌC TỰ NHIÊN Độc lập - Tự do - Hạnh phúc

số:9//QĐ-ĐHKHTN Hà Nội, ngày Lp tháng 6 năm 2022

QUYÉT ĐỊNH

A en h rey ^^ a

Về việc giao đề tài va cử cán bộ hướng dẫn luận văn thạc sĩ

cho học viên Khóa QH.2021.T.CH

HIỆU TRƯỞNG TRƯỜNG ĐẠI HỌC KHOA HỌC TỰ NHIÊN

Căn cứ Quy vie về Tổ chức và hoạt động của các đơn vị thành viên và đơn vị trực

thuộc Đại học Quốc gia Ha Nội ban hành theo Quyết định số 3568/QĐÐ-ĐHQGNN ngày

08/10/2014 của Giám đốc Đại học Quốc gia Hà Nội;

Căn cứ Quy chế đào tạo thạc sĩ tại Đại học Quốc gia Hà Nội ban hành theo Quyết

định số 4668/OD-DHOGHN ngày 10/12/2014 của Giám đốc Dai học Quốc gia Hà Nội;

_ Căn cứ Quyết định số 250/OD-DHOGHN ngày 18/01/2018 của Giám đốc Đại học

Quốc gia Hà Nội về việc chuyên đôi các ngành, chuyên ngành đào tạo ở Đại học Quốc

gia Hà Nội theo Danh mục giáo duc, đào tao cấp IV trình độ đại học, thạc sĩ, tiễn sĩ;

Theo đề nghị của Trưởng khoa Hóa học và Trưởng phòng Đào tạo

QUYET ĐỊNH:

Điều 1 Công nhận tên đề tài luận văn thạc sĩ và người hướng dẫn học viên cao học

Trương Thị Thùy Trang, ngày sinh 10/10/1999, tại Hà Nội, mã số học viên: 21007863,

như sau:

Tên đề tài: Nghiên cứu hấp phụ xử lý chất hữu cơ khó phân hủy trên vật liệu nano

oxit kim loại được biến tính bề mặt bằng polyme mang điện.

Chuyên ngành: Hóa phân tích; mã số: 8440112.03.

Người hướng dẫn: PGS.TS Phạm Tiến Đức, Trường Đại học Khoa học Tự nhiên

-ĐHQGNN; TS Đoàn Thị Hải Yén, Trường Dai học Khoa học Tự nhiên - DHQGHN.

Điều 2 Cán bộ hướng dẫn và học viên cao học được hưởng các chế độ, quyền lợi

và nhiệm vụ theo Quy chế đào tạo sau đại học ở Đại học Quốc gia Hà Nội.

Điều 3 Trưởng Phòng Đảo tạo, Trưởng khoa Hóa học, cán bộ hướng dẫn và học

viên cao học có tên trong Điều | chịu trách nhiệm thi hành Quyết định nays.

Phụ lục 2 Minh chứng kết quả công bố

Công trình công bố trên tạp chí khoa học quốc tế theo hệ thống ISI

1 Thi Hai Yen Doan, Van Long Dang, Thi Thuy Trang Truong, Thi Ngan Vu,

Thanh Son Le, Thi Minh Thu Nguyen, Minh Ngoc Nguyen, Thu Thao Pham, Shin-ichi Yusa, Tien Duc Pham “Removal of Acid Orange G Azo Dye by

Polycation-Modified Alpha Alumina Nanoparticles” Chem Asian J 2023,

e202300404.

https://doi.org/10.1002/asia.202300404, ISI ỌI.

2 Van Long Dang, Thu Trang Kieu, Thi Thu Thao Nguyen, Thi Thuy Trang

Truong,

Duy Thanh Hoang, Thi Linh Chi Vu, Thi Minh Thu Nguyen , Thanh Son Le, Thi Hai Yen Doan, Tien Duc Pham “Surface modification of zeolite by

cationic surfactant and the application on adsorptive removal of azo dye

Ponceau 4R” Journal of Molecular Structure 1304 (2024) 137619.

https://doi.org/10.1016/j.molstruc.2024.137619 IST Q2.

15

Asian Chemical Editorial Society

AN ASIAN JOURNAL

www.chemasianj.org

Removal of Acid Orange G Azo Dye by Polycation-Modified Alpha Alumina Nanoparticles

Thi Hai Yen Doan," "! Van Long Dang,”! Thi Thuy Trang Truong,“ Thi Ngan Vu,“

Thanh Son Le,“ Thi Minh Thu Nguyen,“ Minh Ngoc Nguyen,“! Thu Thao Pham,

Shin-ichi Yusa,! and Tien Duc Pham*"!

Highly positively charged poly(vinyl benzyl trimethylammonium

chloride) (PVBMA) was successfully synthesized with

approx-imately 82% of yield The PVBMA was characterized by the

molecular weight (M,) of 343.45 gmol'' and the molecular

weight distribution, (Ð) of 2.4 by 'H NMR and SEC

measure-ments The PVBMA was applied as an effective agent for ơ-Al;O;

surface modification in the adsorptive removal of the azo dye

acid orange G (AOG) The AOG removal performance was

significantly enhanced at all pH compared to without surface

Introduction

Adsorption is a popular high-potential technique used for

pollutant removal including organic dyes,” besides other

conventional methods proposed such as advanced oxidation,3

and photocatalytic degradation.5' The advantages of

adsorp-tion are its simplicity, low time consumpadsorp-tion, low cost, and high

efficiency In most cases, adsorbents play one of the most

important roles in pollutant removal performance For

sustain-able development, friendly environmental adsorbents are

preferred such as oxide metals with high porosity, which have

been considered as efficient adsorbents Alumina, especially

alumina with nano-size varying states a, B, and y with greater

[a] Dr T H Yen Doan, Assoc Prof T D Pham

Faculty of Chemistry

University of Science,

Vietnam National University,

19 Le Thanh Tong, Hoan Kiem, Hanoi 100000 (Vietnam)

E-mail: tienduchphn@gmail.com

tienducpham@hus.edu.vn [b] Dr T H Yen Doan, V L Dang

Faculty of Chemistry

University of Science,

Vietnam National University

19 Le Thanh Tong, Hoan Kiem, Hanoi 100000 (Vietnam)

[c] T T Trang Truong, T N Vu, T S Le, T M Thu Nguyen, M N Nguyen

Faculty of Chemistry

University of Science,

Vietnam National University,

19 Le Thanh Tong, Hoan Kiem, Hanoi 100000 (Vietnam)

[d] T T Pham, Prof S.-i Yusa

Department of Applied Chemistry,

Graduate School of Engineering

University of Hyogo

2167 Shosha, Himeji, Hyogo 671-2280 (Japan)

Supporting information for this article is available on the WWW under

https://doi.org/10.1002/asia.202300404

Chem Asian J 2023, e202300404 (1 of 11)

modification The experimental parameters were optimal at

pH 8, free ionic strength, 15min of adsorption time, and

mainly controlled by the PVBMA-AOG electrostatic attractions was better applicable to the Langmuir isotherm and the

pseudo-second kinetic model The PVBMA-modified ơ-Al;O;

demonstrates a high-performance and highly reusable ent with great AOG performances of approximately 90.1% after

adsorb-6 reused cycles.

specific surface areas, is one of the most popular mineral

components, presenting as high-performance adsorbents.?

Among the various alumina states, the alpha alumina (œ-Al;O:)

nanoparticles with the highest temperature resistance and

relative specific surface area were successfully applied to

remove organic pollutants."9!

On the other hand, coloring agents such as dyes and pigments are diversely used in the textile, paper, plastic,

cosmetic, and food industries.” Industrial effluents without

proper treatment threaten the environment and human health The dyes are usually accumulative, highly stable, difficultly naturally degradable, and hard discolorable in aquatic

environments."*" Azo dyes are the most commonly used, representing about 50-70% of entire dye applications."§!”

Removing the azo dyes from the effluents is necessary due to

their teratogenic and carcinogenic abilities."*?" Among the azo

dyes, acid orange G (AOG) is known as a synthetic-origin hazard

by the United States Environmental Protection Agency

(USEPA).2" The AOG is represented by a mono azo group

(—N=N-—) and two anionic groups (—SO;ˆ) bound to aromatic rings These molecular characteristics lead to its water-solubility

and pH stabilization!??” Therefore, the sciences have paid

attention to AOG removal An AOG maximum adsorption

capacity of 5.48 mggˆ' was determined through adsorption on

the modified sawdust while the unmodified sawdust efficiency

was not reported.”*! On the other hand, the AOG adsorption

capacity on the sawdust adsorbents increased from about 24 to

about 44% without and with modification by H,SO,,

respectively.” The potential of alumina in azo dye adsorptive removal has been affirmed in several researches.526' However,

the azo dye removal efficiency through adsorption onto the Al;O: material has been limited due to a lower specific surface area compared with the other alumina states Therefore, surface

ơ-modification is required It has been constantly concerned with polymer-adsorbent surface modifiers to improve not only the

© 2023 Wiley-VCH GmbH

Asian Chemical

Editorial Society

ACE

specific surface area but also the surface charge density.2

The AOG removal percentage was enhanced from 65.16% by

the use of raw chitin to 81.20% by using the

polystyrene-modified chitin adsorbent.”® The AOG adsorption performance

of the unmodified chitosan was remarkably improved from 1.7

to 63.7mggTM' employing the N-vinyl-2-pyrrolidone-modified

chitosan adsorbent.” Whereas, the efficiency of polycation

application as an efficient surface modifier on organic pollution

removal was proved elsewhere.9# Especially, the quaternary

ammonium base polyelectrolytes have been considered as a

highly positively charged surface-active modifier because their

permanent charges readily attach to the anionic azo dye

AOG.*2 Following, the electrostatic attractions between the

dyes AOG and the adsorbents were impulsive, enhancing the

higher AOG removal efficiency On the other hand, the

quaternary ammonium base polyelectrolytes are stable in

general, unaffected by pH, and strongly cling to the surfaces."

The removal efficiency of the anionic azo dye new coccine

reached about 87% by using polycation

poly-diallyl-dimeth-ylammonium chloride to modify silica.#” Moreover, to control

the AOG adsorption process, the adsorption dynamics and

kinetics should be clarified Adsorbate-adsorbent interactions

and the adsorption capacity of the adsorbent were detailed by

the adsorption isotherms.”” Some popular models including

Langmuir, Freundlich, and two-step were employed to interpret

the AOG dye adsorption isotherm."**! Meanwhile, the

pseudo-first- and -second-order models are often used to evaluate the

AOG adsorption kinetics.32%

In this study, a highly charged polycation PVBMA was

successfully synthesized, characterized, and applied as a surface

modifier of a-Al,O; particles for the first time The adsorptive

removal process of azo dye AOG on the PVBMA-modified

a-Al,O; particles was systematically investigated The AOG

adsorption nature was clarified by the isotherms and kinetics

and the AOG adsorptive removal process was confirmed by

Fourier-transform infrared (FT-IR) analysis of samples before and

after adsorption.

Results and Discussion

Polycation PVBMA synthesis

The polycation PVBMA was synthesized via free-radical

polymer-ization (FRP) After purification, the results of the 'H NMR and

SEC were performed in Figure 1.

As seen in Figures 1(a) and (b), the proton signals at about

5.99 (a) and 5.48 (b) ppm, respectively in the 'H NMR spectra of

PVBMA before the polymerization, were not observed in the

spectra of PVBMA after the polymerization in D,O at 25°C The

peak disappearance in the 'H NMR spectra of PVBMA before

and after polymerization indicates that double bonds

disap-peared and the monomer conversion was approximately 100%.

About 14.8 g PVBMA was recovered by a free-drying method It

results in a synthesized yield of the PVBMA obtained of 81.8%

(Table 1) Figure 1(c) illustrates that the large and small peaks

eluted in turn at 22 and 36min indicated for PVBMA and

Chem Asian J 2023, e202300404 (2 of 11)

Elution time (min)

Figure 1 The 'H NMR spectra (a) before and (b) after polymerization, and (c)

SEC elution curve of the polycation PVBMA.

Table 1 The characteristics of the synthesized PVBMA determined by the

SEC measurement.

Amount Yield Mạ My, dD

(g) (%) (g.mol”) (g.mol ")

14.8 81.8 143.30 343.45 24

solvent (H;O) and air On the other hand, the M,, M,, and Ð

values of PVBMA were correspondingly determined to be about

143.30, 343.45 gmol, and 2.4 by the SEC measurement

(Table 1) The PVBMA synthesized using the free radical process was a high molecular weight and strong positive functional

amide group -N'(CH;);, which was beneficial for better

adsorption of negatively charged molecules On the other hand, the average pore width of the a-Al,O; particle of approximately

18.04 nm (determined by the BJH method) was much larger than the PVBMA diameter of about 2.30 nm (calculated by the

viscosity method)." In other words, PVBMA molecules could be

incorporated into the a-Al,O; particles It suggests that the PVBMA molecules could be also absorbed into the ơ-Al;O;

particles Therefore, the PVBMA can be a promising polycation

for modification of the alumina surface through sorption.

© 2023 Wiley-VCH GmbH

Asian Chemical Editorial Society

ACE

Modification through PVBMA sorption on the synthesized

a-AIl;O; nanoparticles

PH and ionic strength effects

Figure 2(b) exhibits that the PVBMA sorption performance

slightly increased in the pH range from 1 to 8, and the optimum

was reached at pH 8, then lightened as the pH was higher than

8 It should be noted that the ơ-Al;O; original functional group

of -OH might be unchanged or changed to be -OH;' and —OTM

depending on pH.°”7 Moreover, the a-Al,O; isoelectric point

(IEP) of about 6.7 determined (Figure 2(a)) was consistent with

the previous report.*! On the other hand, the PVBMA with the

Figure 2 (a) The ¢ potential of œ-Al;O; as a function of pH in 1 mM NaCl and

effects of (b) pH and (c) ionic strength on the PVBMA adsorption on the

surface group -O~ and the —N” (CH;); on the PVBMA molecules.

Besides the electrostatic interactions, the non-electrostatic interactions between PVBMA molecules were suggested to

control the PVBMA sorption, introducing insignificant changes

in the PVBMA sorption capacity with the pH changes At pH 8,

the highest PVBMA sorption capacity was obtained Therefore, the optimal pH found was 8.

The PVBMA sorption performance remarkably increased with the ionic strength change from 1 to 100 mM NaCl, then

reduced with continuous ionic strength increment (Figure 2(c)).

It implies that the PVBMA sorption on the œ-Al;O; was governed

by both electrostatic and non-electrostatic interactions It was

consistent with previous results.°°”! That is, the electrolyte ion

presence promoted the non-electrostatic interactions between the PVBMA molecules under the NaCl concentration lower than

100 mM, according to screening-enhanced adsorption while, the electrostatic interactions between the PVBMA molecules and the a-Al,O; particles were screened under the NaCl higher than 100 mM following screening-reduced adsorp-

Mean-tion The ionic strength was optimized at 100 mM NaCl due to

the highest PVBMA sorption performance achievement.

Sorption isotherm models

The Freundlich sorption isotherm provided a better fitting with

the experimental data with higher correlation coefficients, R?

than the Langmuir sorption isotherm (Figure 3(a) and ure S1) In the initial PVBMA/o-AlạO; weight ratio ranges of

Fig-0.005-0.2, it likely implies that multiple layers of PVBMA were formed on the heterogeneous ơ-Al;O; surface with diverse

functional groups of —OH, —O, OH,*, and O~.8”#! In addition,

the PVBMA sorption took place strongly and favorably because the parameter of 1/n was in the range of 0.5-1 (Table 2).

Figure 3(b) depicts that the Qpygma remarkably increased

from 0.95 to 37 mgg | corresponding with 6.33-56.10% of the

PVBMA sorption efficiencies while the initial PVBMA tration increased from 25 to 1000 ppm at pH 8 under different ionic strength conditions Also, the PVBMA sorption isotherms well followed the two-step model using the fit parameters

concen-indicated in Table 3 It was clarified that the PVBMA sorption

onto the ơ-Al;O; surface occurred in two steps as well as the

Table 2 Fitting parameters for the PVBMA sorption isotherms on the Al,0 particles following the Freundlich model.

a-NaCl (mM) 1 10 100 150

R? 0.9489 0.9189 0.9615 0.9516 K; (mg"!1g=1L) 0.097 0.594 18.336 8.792

1⁄n 0.73 047 0.78 0.90

n 1.38 211 1.28 1.11

© 2023 Wiley-VCH GmbH

Asian Chemical Editorial Society

Figure 3 PVBMA sorption isotherms on the ơ-Al;O; particles following: (a)

the Freundlich model, and (b) the two-step model at different ionic

strengths: (IN) 1 mM, (@) 10 mM (A) 100 mM, and (®) 150 mM NaCl.

Table 3 Fitting parameters for the PVBMA sorption isotherms on the

a-Al;O; particles by the two-step model.

sorption process was driven by both electrostatic and

non-electrostatic interactions The equilibrium constant of the first

sorption step, k, is much lower than the equilibrium constant of

the second sorption step, k; in all ionic strengths In addition,

the k, value increases with increasing NaCl concentration from

1 to 150 mM The phenomena proved that the PVBMA sorption

was predominantly controlled by the hydrophobic interactions

Chem Asian J 2023, e202300404 (4 of 11)

CHEMISTRY

AN ASIAN JOURNAL

between PVBMA molecules on the particle surface It is consistent with the ionic strength effect on the PVBMA sorption

observed above Furthermore, the initial PVBMA concentration

of 1000 ppm was used to achieve a sufficient œ-Al;O; surface net charge.

Summarily, the a-Al,O; particle modification through PVBMA sorption was optimized at pH 8, ionic strength of

100 mM, contact time of 2h, and initial concentration of

500 ppm.

AOG removal by using the PVBMA-modified a-Al,0; particles

PH and ionic strength effects

The most important parameters that strongly affect the adsorption of charged molecules are pH and ionic strength due

to interference of interaction forces, and the natures of both absorbate and absorbent.

Figure 4(a) shows that the AOG removal performance was

remarkably enhanced by using the PVBMA modifier in

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Asian Chemical Editorial Society

ACE

ison with the absence of PVBMA at all pH values It proves the

necessity of the a-Al,O; surface modification through highly

positively charged PVBMA adsorption On the other hand, the

AOG removal performance decreased from 33.51 to 11.02%

with the corresponding pH change from 4 to 11, due to the

electrostatic attractions and the repulsions between -OH,* and

—O” groups on the ơ-Al;O; surface and the —SO;~ group of the

AOG dye at acidic and alkaline environments, respectively.

Meanwhile, with the PVBMA modification, the AOG removal

performance improved by increasing the pH from 4 to 7 and

then decreased by continuously increasing the pH until 11

(Figure 4(a)) As found above, the polycation PVBMA adsorption

was promoted at pH from 4 to 8, and more AOG dyes were

adsorbed on the adsorbent surface due to the electrostatic

attractions between the positively charged adsorbed PVBMA

molecules and the negatively charged AOG dyes In other

words, fewer AOG dyes remained by increasing the pH higher

than 8, due to fewer adsorbed PVBMA molecules on the

modified surface However, the maximum AOG removal

performance was significantly achieved at pH7 (instead of

pH 8), which might be due to the deprotonation of AOG

functional groups -SO;H and —OH corresponding with the pK,

of 1 and 11.5, which could be effective to the PVBMA-AOG

interaction numbers.“““! Thus, pH 7 was chosen for the AOG

adsorption.

The AOG removal performance decreased from 98.51 to

43.00% with the ionic strength increment from 0 to 100 mM

NaCl, respectively (Figure 4(b)) Herein, the electrolyte ions

screened electrostatic attraction between the positively charged

adsorbed PVBMA and negatively charged AOG dyes due to

screening-enhanced adsorption, suggesting that the

electro-static attraction forces dominated on the AOG removal.2646

Moreover, the AOG adsorptive removal was conducted without

adjusting the ionic strength for the next investigated

experi-ments.

Contact time and adsorbent dosage effects

The contact time and adsorbent dosage strongly affect the AOG

adsorptive removal efficiency Therefore, it is necessary to

investigate these two parameters.

As observed, the AOG decolorization occurred right after

the mixing event, suggesting that the AOG adsorption process

immediately took place A certain adsorbent dosage

contrib-uted to the given available adsorbent sites for a fixed adsorbate

amount It could be explained that available surface-active sites

were numerous at the initial stage, and then adsorbent site

saturation happened after a certain time The AOG removal

performance achieved a high value of approximately 94% and

no significant change after 15 min of the contact time for both

AOG initial concentrations of 10 and 20 ppm (Figure 5(a) and

Figure S2) Otherwise, it implies the strong interactions between

the AOG dyes and the modified alumina particles Also, the

time effect reveals that the AOG adsorption reached equilibrium

within 15 min For further investigations, the AOG adsorption

was conducted at the contact time of 15 min.

Chem Asian J 2023, e202300404 (5 of 11)

initial AOG concentrations.

On the other hand, the AOG removal performance was substantially raised with the a-Al,O; dosage increment (Fig-

ure 5(b)) With the adsorbent dosage increment from 0.25 to

10 mgmLˆ', the AOG removal performance went up from 19.23

to 98.13% and from 16.54 to 95.54% with the AOG initial concentration of 10 and 20 ppm, respectively (Figure 5(b) and Figure S3) Obviously, greater adsorption active sites were provided by a higher a-Al,O; particle amount, promoting more AOG adsorbed onto the modified surface.

AOG adsorption isotherm

Figure 6(a) exhibits that the AOG concentration increment, the

adsorption capacity of the AOG dye on the PVBMA-modified

a-Al,O; particles raised due to kinetically controlled adsorption.“

Moreover, the AOG adsorption isotherm better obeyed the

Langmuir model (with higher correlation coefficients, R?) than

the Freundlich model (Table 4) It reveals that the adsorbed AOG dyes were limited to one adsorbate layer on the modified

© 2023 Wiley-VCH GmbH

Figure 6 AOG adsorption isotherms: (a) Langmuir and (b) Freundlich with

varying NaCl concentrations of: (I) 0, (@) 1, and (A) 100 mM.

Table 4 The parameters for the AOG adsorption onto the

PVBMA-modified a-Al,0; nanoparticles with the different adsorption isotherms

Langmuir and Freundlich.

NaCl Langmuir Freundlich

d-Al,O; surface.“*! On the other hand, the Langmuir constant, K,

reduced from 0.23 to 0.03 with 100times increasing the NaCl

concentration from 1 to 100 mM Such observation suggests

that the electrostatic attractions between the PVBMA and the

AOG were dominant and this trend was consistent with found

results above in the ionic strength effect part The separation

dimensionless factor, R, was in the range of O to unity,

indicating that the AOG adsorption was favorable (Table 4).

Chem Asian J 2023, e202300404 (6 of 11)

ered to fit with pseudo-first- and -second-order models.

The AOG adsorption kinetics on the PVBMA-modified

a-Al,O; particles were better fitted by the pseudo-second-order

kinetic model with high R2 values of 0.9967 and 0.9984 at the

different AOG initial concentrations of 10 and 20ppm,

respectively (Figure 7 and Figure S4) It assumes that the

interactions between the AOG dyes on the modified particles

were primarily governed by chemisorption.“”!

Adsorptive removal of the AOG dyes by using the a-Al,O;

nanoparticle modified by polycation PVBMA

The modification of the a-Al,O; nanoparticles through the PVBMA adsorption and the AOG removal through the adsorp-

tion onto the PVBMA-modified particles were affirmed by the FT-IR spectroscopy (Figure 8) In the former, the PVBMA adsorbed onto the ơ-AlạO; nanoparticles was confirmed based

on functional group changes The Al-O vibration at 763.67 and

1028.84 cm ` in the a-Al,0; spectrum correspondingly changed

to 757.89 and 1024.02 cmTM' in the PVBMA-modified a-Al,O;

spectrum.°°>" Meanwhile, the -OH vibrations attributed at

3465.46 and 1454.06 cm! in the œ-Al;O; spectrum were slightly moved to 3461.60 cm' and disappeared, respectively, in the

PVBMA-modified-a-Al,O, spectrum.2°” It reveals that the

electrostatic interactions between —N*(CH;); in the PVBMA and

—O” were generated from —OH in the Al;O: particles at pH 8.

The bands at 2926.45 and 3020.94 cm" presenting for N*-C

vibrations in the PVBMA spectrum were not observed in the

PVBMA-modified-a-Al,O; spectrum Lately, the bands at 2926.45

and 3020.94cm' attributed to the N*‘-C vibrations in the

PVBMA spectrum were absent in the AOG- PVBMA-modified

PVBMA-© 2023 Wiley-VCH GmbH

Asian Chemical Editorial Society

Figure 8 FT-IR spectra of: (—) a-Al,0; nanoparticles, (—) PVBMA, (—) azo

dye AOG, (—) PVBMA-modified-ơ-Al;O; particles, and (—)

AOG-adsorbed-PVBMA-modified-ơ-Al;O; particles

Al,O; Meanwhile, the presence of C-N* vibration at

976.77 cm in the PVBMA spectrum raised to 971.95 cm“ in

the AOG-PVBMA-modified-o-Al,O; spectrum.P^°” Furthermore,

the bands at 1142.62 and 1185.04 cm~' attributed to -S=O in

the AOG spectrum disappeared in the AOG-

PVBMA-modified-a-Al,O; spectrum.P256°” The —N=N— vibration was displayed at

1448.12 cm” in the AOG spectrum and 1435.74cm'' in the

AOG- PVBMA-modified a-Al,O, spectrum It suggests the

electrostatic attraction between —N”(CH;); in the PVBMA and

~§O,~ in the AOG.

Reusability of the a-Al,0; adsorbents

The œ-Al;O; adsorbents were reused through the HCI treatment

with different HCl concentrations of 0.1-5 M It was proposed

that almost adsorbed AOG dyes (approximately 92.09%) were

desorbed from the modified a-Al,0O; surface by using 5 M HCl

compared with approximately 98.89% AOG adsorption with the

AOG initial concentration of 10 ppm Therefore, the œ-Al;O;

adsorbents were treated with 5 M HCI before reusing them for

the next adsorption cycles As investigated above, both the

PVBMA and the AOG adsorption efficiencies were low at the

low pH due to the electrostatic repulsions between the PVBMA

and the ơ-Al;O;, and less PVBMA adsorbed onto the particle

surfaces, respectively The addition of the 5M HCI solution

might decrease the solution pH, resulting that either the

adsorbed AOG or both PVBMA and AOG could be desorbed

from the adsorbent surfaces In addition, a-Al,O; dissolution

under acid conditions could be one reason Moreover, the use

of high HCI concentration (5 M) suggests strong electrostatic

attractions between the AOG and the modified adsorbents In

Figure 9, the AOG adsorption performance reduced to a quite

high value of 90.13% even after 6 reusability cycles, proving the

high reusability of the œ-AlạO; adsorbents On the other hand,

the PVBMA-modified-a-Al,O; adsorbents used in the present

study achieved the highest adsorption capacities even with low

œ-Al,O; adsorbent dosage (Table 5) Our results again

demon-strate that the PVBMA-modified-a-Al,O; particles are a

high-Chem Asian J 2023, e202300404 (7 of 11)

Table 5 Maximum AOG adsorption capacity with varying adsorbents.

Adsorbents đmax Madsorbent Reference

Perchloric acid-modified sawdust 5.48 20 [23]

Activated carbon-prepared phespe- 9.13 21.6 [60]

sia populnea pods

performance adsorbent for azo dye removal from aqueous

solutions.

Conclusions

It can be concluded that the highly charged polycation PVBMA synthesized was a highly effective agent to modify the ơ-Al;O; particle surface The AOG removal process was strongly effective by pH, ionic strength, contact time and the ơ-Al;O; dosage The results showed that the AOG removal efficiency

was remarkably achieved up to approximately 98.89% at pH 8, the ionic strength reduction, and the increments of both the contact time and the ơ-Al,O; dosage The AOG adsorption on the modified ơ-Al;O: particles was favourable and well-suitable with the Freundlich isotherms and the pseudo-second kinetic model The electrostatic attractions between adsorbed PVBMA

molecules and AOG dyes were dominant on the d-Al;O;

nanoparticles The PVBMA-modified a-Al,O; were highly able and high-performance adsorbents for dye removal in water

reus-environments.

© 2023 Wiley-VCH GmbH

ACES tiiraisooev

Experimental Section

Synthesis of polycation PVBTMAC

Vinyl benzyl trimethylammonium chloride (VBMA, 99% of analytical

purity, Sigma-Aldrich, St Louis, MO, USA) was applied without any

further purification 4-Cyanopentanoic acid dithiobenzoate (CPD),

synthesized following a previous method, was used as a chain

transfer agent." An initiator, 4,4-azobis(4-cyanovaleric acid)

(V-501, 98% of analytical purity), and a crosslinking agent,

N,N’-methylenebis(acrylamide) (BIS, 97% of analytical purity), were

purchased from Wako Pure Chemical (Osaka, Japan) and used

without any further treatment Water was purified using an

ion-exchange column.

PVBMA was synthesized via free radical polymerization (FRP) by

using BIS as a crosslinker The mixture including 18.10g of

monomer VBMA and 0.240g of V-501 and 1.32mg BIS was

dissolved in 42.80 mL of the deionized water Then the solution was

purged with argon gas for 30min The polymerization was

conducted at 60°C for 16h The reaction solution was dialyzed

(molecular weight cut-offs, MWCO: 5~ 1000) against the deionized

water for 2 days.

Synthesis of nanosized alpha-alumina

Nanosized alpha alumina (a-Al,03) particles were solvothermally

synthesized following the previous method and used as

adsorbents The NaOH pellets and (AI(NO,), (analytical reagent,

Merck, Germany) were used to respectively prepare 4M sodium

hydroxide (NaOH) and 1M aluminum nitrate (Al(NO;)3) solutions.

Then, the NaOH solution was added to the Al(NO;); solution to

form alumina hydroxide precipitation The Al(OH); precipitates were

centrifuged for 15 min Then, the collected Al(OH); suspensions

were raised with ultrapure water until reaching a neutral pH before

drying at 80°C for 24 h Finally, œ-Al;O; particles were formed based

on putting the Al(OH); in an oven at 1200°C for 12h The

synthesized ơ-Al;O; adsorbents were characterized to be spherical

particles with a nano-size of approximately 70nm of diameter

(Figure 10), and a specific surface area of 6.08 mˆg”' by

trans-mission electron microscopy (TEM, H7650, Hitachi, Japan) and

Brunauer-Emmett-Teller (BET) methods (AMI-300, Altamira

Instru-ments, USA), respectively.

The zeta (¢) potential of ơ-AlạO; was examined by Smoluchowski’s

equation by electrophoretic mobility using a Zetasizer Nano

(Malvern, England) at 1mM NaCl The É potential of a-Al,O; at

different pH was conducted to evaluate the surface charge of

a-Al,O3 (Figure 2(a)), and the point of zero charge was about 6.7 that

agreed well with its value of œ-Al;O;.

Figure 10 The TEM image of the ơ-Al;O; particle

Chem Asian J 2023, e202300404 (8 of 11)

AIl;O; particle surface Azo dye, acid orange G (AOG, purity > 99%,

Shangdong, China) with a molecular weight of 45.237 gmol”' was

applied as an adsorbate Stock solutions of 10* ppm of each PVBMA

and AOG were prepared Meanwhile, working solutions were prepared from stock solution dilution The chemical structures of polycation PVBMA and the AOG dye are indicated in Figure 11 lonic strength was controlled by using 0.1 and 1M NaCl solutions prepared from analytical reagent NaCl (Merck, Germany) Solutions including 0.1 M HCI and 0.1 M NaOH (Merck, Germany) were added

to experimental solutions to adjust pH under a pH meter (Hanna, California, USA) Ultrapure water (resistance of 18.2 MQcm, Labcon-

co, USA) was used to prepare all solutions.

Modification of ơ-Al;O; using the highly positively charged polycation

Modification of a-Al,O; by the PVBMA adsorption

Sonication of the synthesized ơ-Al;O; nanoparticles was conducted for about 20min to avoid particle aggregation In a surface modification, a suitable volume of the PVBMA stock solution was mixed with ơ-Al;O: in a 15 mL tube under the desired conditions Effect parameters including pH, NaCl concentration, and initial

PVBMA concentration were investigated The mixture was shaken

for approximately 2 h by a vertical shaker under different pH and ionic strength conditions Then, the PVBMA-modified ơ-Al;O;

suspension was collected and rinsed with ultrapure water to

remove excess polycation PVBMA after centrifuging for 15 min at

4000 rpm with a centrifuge (Hermle, Labortechnik, Wehingen,

Germany).

The ơ-Al;O: nanoparticles were modified by PVBMA sorption under

the same experimental conditions of 5mgmL * of the a-Al,O;

dosage, 50 ppm of the PVBMA initial concentration, 2h of the

contact time, at pH range 4-11 with 1 mM NaCl and in the NaC concentrations from 1 to 150 mM.

On the other hand, the experiments to clarify the PVBMA sorption isotherm models were conducted with varying conditions of pH 8,

contact time of 2h, the a-Al,0; dosage of 5mgmL', the initia

concentration range of 25-1000 ppm, and different ionic strengths

ACES tiiraisooev

AOG adsorptive removal using synthesized-PVBTMAC-modified

a-Al,O; nanoparticles

The AOG dyes were adsorbed through the adsorption onto these

PVBMA-modified ơ-Al;O; nanoparticles under room temperature

and different investigated conditions, including ionic strength, pH,

contact time, adsorbent dosage and adsorbate dosage The

standard deviation of each result was calculated based on three

repeated experiments.

The pH and ionic strength effects on the AOG adsorption onto the

œ-Al;O: particles modified by polycation PVBMA was clarified with

varying experimental conditions of 5mgg ' of the a-Al,O;

adsorbent dosage, 10 ppm of the AOG initial concentration, 10 mM

NaCl, adsorption time of 2 h.

Methods

Ultraviolet-Visible (UV-Vis) spectroscopy

An Ultraviolet-Visible (UV-Vis) spectroscopy equipped with a

spectrophotometer (UV-1650 PC, Shimadzu, Japan) was used to

determine the concentrations of dye AOG and polycation PVBMA in

aqueous solutions The measurement wavelengths of the AOG and

PVBMA were 478 and 223 nm, respectively.

The PVBMA and AOG adsorption performances (H, %) were

calculated by equation (1) as below:

The PVBMA and AOG adsorption capacities onto the unmodified/

modified œ-Al;O; nanoparticles were determined by equation (2).

G- G

m

n= xV (2)

where q, is the adsorption capacity of polymer (mgg/') at a contact

time t (min), V is volume of polymer solution (L) and m is the

a-Al,O; mass (g).

PVBMA and AOG adsorption mechanisms

The adsorption isotherms of the PVBMA and AOG onto the

unmodified and modified ơ-Al;O; particles, respectively, were

suitably fitted with typical models of Langmuir, Freundlich, and

two-step with linear and non-linear regression.®! Each adsorption

isotherm model was described in detail below.

The Langmuir-type model specifies for mono adsorbed layer

formed on the a-Al,O; nanoparticle surface shown in equation (3).

The polymer adsorption favorite was evaluated according to

1

logq, = logK; + - logC, (5)

where K, is the Freundlich constant ((mgg ') (Lmg ')'”) and n is

the adsorbed layer number.

The two-step model with a general isotherm equation was:

đmaxKn C (+ k,C,""')

1+k,C.(1+k,C,""')

q (6)

where k, and k, are respectively the equilibrium constants for the

first and second polymer adsorption step.

PVBMA and AOG adsorption kinetics

The pseudo-first and -second models, suggested by Lagergren are

often proposed to describe the polymer adsorption kinetics of

In(qe — 4) = Inge — Kat (7)

mm

a K4 4 48)

where K, (min ') and K, (gmgˆ min) are respectively the reaction

rate constants of the pseudo-first and pseudo-second models.

Each standard deviation was calculated by at least triple

exper-imental values.

Fourier transform infrared (FT-IR) spectroscopy

The PVBMA and AOG adsorption mechanisms onto the unmodified and modified a-Al,O; nanoparticles were clarified based on the

functional group changes by the FT-IR spectra The PVBMA adsorption was conducted under experimental conditions of the

2h contact time, pH 8, 100 mM NaCl, the 5 mgg ' ơ-Al;O; particles, and the 10‘ ppm PVBMA concentration Meanwhile, the

nano-AOG adsorption was measured at the same initial conditions of the adsorbent dosage and the contact time, but with free salt and

pH 7 After that, the samples were centrifuged for 15 min at

4000 rpm to remove water Then, the a-Al,O; suspensions were collected and dried in an oven at 80°C The FT-IR spectra of the a- Al,03 nanoparticles, the synthesized polycation PVBMA, AOG dye, the a-Al,O; particles modified by PVBMA, and the PVBMA-modified- a-Al,O; particles adsorbed AOG, were carried out in the wave-

spectrophotom-eter (Shimadzu, Japan) at room temperature of 293 K.

© 2023 Wiley-VCH GmbH

Asian Chemical

Editorial Society

ACE

Proton nuclear magnetic resonance ('H NMR) and

size-exclusion chromatography (SEC) measurements

The 'H NMR spectra of the polycation PVBTMAC were recorded by

a JNM-ECZ 400 MHz spectrometer (JEOL, Tokyo, Japan)

Number-average molecular weight (M,), Number-average molecular weight (M„), and

molecular weight distribution, M,/M, (Ð) of the PVBMA were

estimated by the SEC measurement equipped with a refractive

index (RI) detector operating at 40°C 0.3M Na,SO, with 0.5M

acetic acid was used as eluents for PVBMA samples at a flow rate of

0.6 mLminˆ1 at 40°C To estimate the M, and 9, a calibration curve

was constructed using poly(2-vinyl pyridine) standard samples.

Acknowledgements

This research has been done under the research project

QG22.17 of Vietnam Nation University, Hanoi.

We would like to thank Dr Johan Hunziker, IGEPP, INRAE,

Institut Agro, Univ Rennes, 29260, Ploudaniel, France for the

available comments and English check to improve our

manu-script.

Conflict of Interests

The authors declare no conflict of interest.

Data Availability Statement

The data that support the findings of this study are available

from the corresponding author upon reasonable request.

Keywords: alumina nanoparticle

-adsorption - polycation

azo dye acid orange G

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Chem Asian J 2023, e202300404 (11 of 11)

CHEMISTRY

ACES viitcriatsociety AN ASIAN JOURNAL

Research Article RESEARCH ARTICLE

Dr T H Yen Doan, V L Dang, T T.

Trang Truong, T N Vu, T S Le, T M.

Thu Nguyen, M N Nguyen, T T Pham, Prof S.-i Yusa, Assoc Prof T D Pham*

1-12

—_~> “ắc Removal of Acid Orange G AzoDye &

Low AOG removal performance, High AOG removal performance, by Polycation-Modified Alpha

pa pe? Alumina Nanoparticles

Polycation PVBMA was synthesized, were dominant The AOG adsorption

characterized, and applied as an was better suitable with Langmuir

effective œ-Al;O; modifier on adsorp- isotherm and pseudo-second models.

tive removal of azo dye AOG Approxi- The ơ-Al;O; adsorbent was highly

mately 98.9% of the AOG was reusable with about 90.1% of the AOG

excluded from aqueous solution The removal efficiency after 6 reused

PVBMA-AOG electrostatic attractions cycles.

| ## SPACE RESERVED FOR IMAGE AND LINK

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Dr Thi Hai Yen Doan Van Long Dang

Thi Thuy Trang Truong Thi Ngan Vu

Thanh Son Le Thi Minh Thu Nguyen

Minh Ngoc Nguyen

Thu Thao Pham http://orcid.org/0000-0002-9087-7417 Prof Shin-ichi Yusa

Assoc Prof Tien Duc Pham

Journal of Molecular Structure 1304 (2024) 137619

Contents lists available at ScienceDirect

Journal of Molecular Structure

®

Check for

Surface modification of zeolite by cationic surfactant and the applicationon =

adsorptive removal of azo dye Ponceau 4R

Van Long Dang, Thu Trang Kieu, Thi Thu Thao Nguyen, Thi Thuy Trang Truong,

Duy Thanh Hoang, Thi Linh Chi Vu, Thi Minh Thu Nguyen, Thanh Son Le, Thi Hai Yen Doan 5

Tien Duc Pham ˆ

Faculty of Chemistry, University of Science, Vietnam National University, Hanoi - 19 Le Thanh Tong, Hoan Kiem, Hanoi 100000, Vietnam

ARTICLE INFO ABSTRACT

Keywords: The zeolite Permutit (Per) with the cubic crystal, 1.66 of the SiO2/Al2O3 ratio, 44.81 m^„g 1 of the specific

Zeolite surface area, 1.7 nm of the average pore radius, and the typical bonds of Si-OH, Si-O-Si, Si-O-Al, and O-Si-O-Si

Dye removal was investigated in the present study The adsorptive removal efficiency of the azo dye PC4R was almost doubled

nàn nến from about 53.23% to 90.06% by Per surface modification with the cationic surfactant cetyltrimethylammonium

Ponceau 4R bromide (CTAB) as an effective and high-performance adsorbent The PC4R adsorptive removal was optimized at

independent variables of pH 4, the ionic strength of 10 mM NaCl, the Per dosage of 6 mg.mL~1, and the short

contact time of 15 min Both the Langmuir and Freundlich models were reasonable to describe the PC4R

adsorption isotherms on the CTAB@Per while the PC4R chemisorption kinetics were well accorded with the

pseudo-second-order model The PC4R multilayer adsorption capacity achieved an extrapolated maxima of

15.470 mg.g-! The PC4R adsorption mechanisms were demonstrated by the FT-IR measurement to be primarily

the electrostatic attractions between the CTAB and the PC4R, dipole-ion interactions, and hydrogen bondings between the PC4R molecules.

1 Introduction

In developing countries, environmental pollution has become a

serious problem due to fast industrialization, and population growth.

Recently, the rapid development of the textile and dyeing industries

might threaten aquatic life and human health if their effluents

con-taining toxic inorganic and organic components were unproperly treated

[1,2] It is pointed out in a recent statistic, about 20% of the nearly 30%

dye loss during operations were released into the effluents [3,4].

Meanwhile, the synthetic azo dyes specified by functional azo groups -N

= N- primarily account for approximately 50 — 70% of annual dye

ap-plications [5,6] The azo dyes were especially noticed to cause children’s

hyperactivity [7] For this reason, the dye level was authorized in the

foods and beverages, for example 50 — 500 mg.kgTM! of Ponceau 4R

(PC4R) maximum amount limited by the Codex General Standard for

Food Additives [8] It is evident that PC4R is an azo dye with diversely

used in many fields such as food and beverage colorings, and textile

pigments [9] Moreover, the PC4R is high stability under light, heat,

* Corresponding authors.

acid, and microorganisms due to the molecular structure of the aromatic

rings [10,11] Azo dye removal from aqueous solution has been cerned for many scientists Different removal techniques were thor- oughly studied to enhance the removal efficiencies of the azo dyes in common as well as the PC4R from aqueous media Nowadays, many available techniques involving coagulation [12], electro-oxidation [1 3],

con-photocatalyst [14,15], and adsorption [16,17] have been applied to

remove the PC4R One of the most common techniques is adsorption due

to its extensive advantages of low cost, simple design, easy operation,

high efficiency, and especially nontoxic sub-compound generation [3].

With an initial concentration of about 75 mg.L ~ Ì, the maximum PC4R

removal efficiency was achieved about 78.59 and 90.83% through adsorption using nanocrystalline granular ferric hydroxide (GFH), and almond shell-prepared activated charcoal, respectively [16,18].

In adsorption, adsorbent type significantly governs the pollutant removal efficiency Especially, the use of adsorbents similarly chemi- cally composed with natural components might cut down secondary emission sources in the environment Among different natural minerals,

E-mail addresses: haiyendoan90@gmail.com, doanthihaiyen@hus.edu.vn (T.H.Y Doan), tienducpham@hus.edu.vn, tienduchphn@gmail.com, ducpt@vnu.edu.vn (T.D Pham).

https://doi.org/10.1016/j.molstruc.2024.137619

Received 13 May 2023; Received in revised form 22 October 2023; Accepted 20 January 2024

Available online 26 January 2024

0022-2860/© 2024 Elsevier B.V All rights reserved.

V.L Dang et al.

zeolite has been preferred employing as an effective adsorbent for

de-cades Zeolite was constructed by (AlOa)°~ and (SiO4)*~ tetrahedrons,

forming micropores, small cages, and narrow channels These structure

characteristics resulting in great porosity, and high specific surface area

were advantageous for the adsorptive removal of the pollutants [19].

However, it could selectively adsorb small molecules and effectively

reject big molecules [20,21] Whereby, to retouch this disadvantage, the

zeolite surface covered with cationic surfactant

cetyl-trimethylammonium bromide (CTAB) could be used to boost the

adsorptive removal efficiency of the negatively charged PC4R molecules

vice electrostatic attractions Whereas, clarifications of the PC4R

adsorption isotherms and kinetics are essential for adsorptive removal

control Generally, the PC4R adsorption isotherms on solid surfaces

were verified by the Langmuir, Freundlich, and two-step isotherms,

while the PC4R adsorption kinetics were revealed by the

pseudo-first-and -second-order models [16,22].

For the purpose of the PC4R removal enhancement in water

envi-ronment, the commercial artificial zeolite, Permutit was employed as an

effective adsorbent after surface modification by CTAB The

character-istics of the Permutit were evaluated by modern physicochemical

techniques The effective parameters, the mechanisms, and the kinetics

of both the CTAB and the PC4R adsorptive processes on the unmodified

and modified Per, respectively were comprehensively investigated The

high potential of the CTAB-modified Per adsorbents in the PC4R

adsorptive removal was also proved through the comparison with that

using the unmodified Per adsorbents.

2 Materials and methods

2.1 Materials

Commercial artificial zeolite, Permutit (Per, purity > 97%, Macklin

Co., Ltd, Shanghai, Chinese) with a chemical formula of (SiO2),(Al203)y

and a molecular weight of 218.24 g.mol~! was purchased and used as an

adsorbent To prepare the Per stock suspensions, 2.5 g of the Per

ad-sorbents were weighed and introduced into a 50 mL falcon The Per

materials were filled up with distilled water until the mark before

vigorously shaking for 2 h by an orbital shaker (Lauda, Berlin,

Ger-many) To prevent aggregation, the Per suspensions were daily shaken

for about 30 min before each adsorption experiment The Per was

modified by cationic surfactant, Cetyltrimethylammonium bromide

(CTAB, the molecular weight 364.45 g.mol}, purity > 99%, Mumbai,

India) An azo dye Ponceau 4R (PC4R, molecular weight 604.46 g.

mol}, purity > 82%, Merck, Germany) The stock solutions of the CTAB

and the PC4R with corresponding concentrations of 1 mol.L ~ 1 and 104

mg.L ~ Ì were prepared, respectively The chemical structures of the

CTAB and the PC4R were depicted in Fig 1 Solutions of 0.1 M NaCl, 1M

NaCl, 0.1 M NaOH, and 0.1 M HCl were used to adjust ionic strength and

Journal of Molecular Structure 1304 (2024) 137619

the solutions pH were prepared in proportion to NaCl, NaOH pellets, and HCI (analytical reagent, Merck, Germany) The daily working solutions were diluted from these stock solutions by the addition of double- distilled water.

2.2 Surface modification of Per by CTAB adsorption

Suitable volumes of the Per adsorbents and the cationic surfactant CTAB were added into a 15 ml falcon After that, a certain NaCl solution volume with an appropriate concentration was introduced to achieve desired ionic strength before pH adjustment The mixture was filled up with distilled water until 10 mL Then, the mixture was homogenously shaken with investigated contact time by using an orbital shaker (Var- ioshake, Mannheim, Germany) The suspensions and solution were separated after centrifuging for 15 min at 6000 rpm by a centrifuge (Hermle, Wehingen, Germany) The experiments were conducted with varying conditions of pH, ionic strength, and initial CTAB concentration

at room temperature The CTAB excesses were formed ion pairs with 200

uL of 0.1% picric acid solution dissolved in 2 mM NaOH solution Then the ion pairs were extracted by 1,2-dichloroethane solvent (analytical reagent, Merk, Darmstadt, Germany) before determining at 378 nm by Ultraviolet-visible (UV-Vis) spectroscopy equipped with a spectropho- tometer (UV-1650 PC, Shimadzu, Japan) [23-25] Meanwhile, the sus- pensions collected at optimal conditions were denoted as CTAB@Per adsorbent that is applied in the PC4R adsorptive removal and

Fourier-transform infrared (FT-IR) measurement.

2.3 PC4R adsorptive removal using the CTAB@Per adsorbents

A certain PC4R volume was adsorbed on the CTAB@Per at varying investigated conditions including pH, ionic strength, contact time, adsorbent dosage, and PC4R initial concentration in a 15 mL falcon The ionic strength and pH were adjusted before adding the distilled water until 10 mL Then the mixture was centrifuged for 15 min at 6000 rpm after shaking Furthermore, the solution of the PC4R excess obtained was measured at 508 nm by the UV-Vis spectroscopy Meanwhile, the suspensions of the PC4R-adsorbed CTAB@Per under optimal conditions were utilized for the FT-IR measurement.

All experiments were carried out at room temperature controlled by

an air conditioner Each experiment was replicated at least three times 2.4 Methods

2.4.1 Determination of characteristics of the Per adsorbents

The characteristics of the artificial Permutit including phase ture, chemical component, specific surface area, and morphology were

struc-analyzed by ray diffraction (XRD, Bruker D8 Advance, Germany),

X-ray fluorescence (XRF, Shimadzu, Japan), Brunauer-Emmett-Teller

(b)

Fig 1 Chemical structures of (a) the cationic surfactant CTAB and (b) the azo dye PC4R.

V.L Dang et al.

(BET, AMI-300, Altamira Instruments, USA) and Scanning electron

mi-croscope (SEM, S-4800, Hitachi, Japan), respectively.

2.4.2 Determination of adsorption performance and adsorption capacity

The adsorption performances of the CTAB and the PC4R on the Per

unmodified and modified by CTAB were calculated as follows in Eq (1).

_— C¡ —C

i

where P (%) is the adsorption performance while C; and Œt (mg.L ~ 1) are

the CTAB or PC4R concentrations before and after the contact time, t

(min), respectively.

The adsorption capacities of the CTAB and the PC4R on the Per

surfaces unmodified and modified by the CTAB were calculated by

Equation (2).

G — Cc,

Q= x M x 1000 (2)

m

where Q (mg.g 1) is the surfactant adsorption capacity, M (g.mol"”) is

the adsorbate molecular weight, and m (mg.mL~?) is the Per dosage.

2.4.3 Adsorption isotherms

Langmuir and Freundlich adsorption models were commonly used to

fit the adsorption isotherms of the CTAB and the PC4R on the

unmodi-fied and modiunmodi-fied Per surfaces [26,27].

Formerly, monolayer adsorption was depicted by the Langmuir-type

model in Eq (3) The adsorption favorite was evaluated by the value of

the dimensionless factor of separation (Ry) in Eq (4) [26].

where Qnax (mg.g ~ Ù) is the maximum adsorption capacity, and K, (L.

mg) is the Langmuir constant.

Furthermore, multilayer adsorption on the heterogeneous adsorbent

surface was assessed by the Freundlich model based on the experimental

data in Eq (5) [28].

1

logQ, = logKp + nIosCc @®)

where Kp (mg"*!.g-.L-") is the Freundlich constant, and n is the

number of adsorbed layers.

2.4.4, Adsorption kinetics

Pseudo-first and -second models expressed in Eqs (6) and (7) were

typically used to clarify the polyelectrolyte adsorption kinetics [29].

Ln(Q — Q,) = InQ, — Kat (6)

t 1 1

Q Ke Q! ”

where Kg (min }) and Kp (g.mg"! min") are the reaction rate constants

of the pseudo-first and pseudo-second models, respectively.

2.4.5 Adsorption mechanisms

The spectra of pure Per adsorbents, pure CTAB, pure PC4R,

CTAB@Per, and PC4R-adsorbed CTAB@Per (collected above) were

recorded in the wavenumber range of 400 — 4000 cmTM! by an

Affinity-1S spectrophotometer (Perkin Elmer, USA) with scans of averagely 20 at

room temperature Adsorption mechanisms were suggested based on the

functional group changes and adsorption isotherms.

Journal of Molecular Structure 1304 (2024) 137619

3 Results and discussions 3.1 Characterization of the Per adsorbent

The Per was constituted by primarily about 61.98% SiO2, 37.25% AlzOas, and minorly 0.16% K20, 0.46% CaO, 0.08% Fe203, 0.07% CuO that was determined by the XRF measurement (Table 1) Two major constructing chemical elements of the Per were silicon (Si), and aluminum (Al) (Fig 2(a)) Accordingly, the Per material was composed

of the Si02/Al203 ratio of 1.66 and the Si/Al ratio of 1.47 (Table 1) On the other hand, the Per chemical formula of (SiO2)2 26(Al203)o,g1 was extrapolated based on the chemical compositions.

The sharp peaks with specific p-spacing values appeared at 7.18° (d=

12.30 A), 10.15 (d = 8.70 A), 20.35° (d = 4.36 A), 21.63° (d = 4.11 A), 22.75 (d = 3.91 A), 23.91° (d = 3.72 A), 26.08 (d = 3.41 A), 27.04° (d= 3.30 A), and 29.89° (d = 2.99 A) characterized for crystalline Per phase

(Fig 2(b)) [30-32] Moreover, no hump background reflected no amorphous Per conversed from the crystal Per [33] Thus, the Per was completely crystallized.

In Fig 2(c), the appearance of a broad band in the range of 3000

-3700 cm! indicated Si-OH stretching vibration in the Per structure

[34] A small peak of -OH bending vibration due to the presence of water

at 1653 cm! [34] In addition, an intensive peak observed at 1004 cm!

specified asymmetric stretching vibrations overlap between bridging Si-O (Si-O-Si) and non-bridging Si-O” (Si-O-Al) [31] Additionally, a

small peak of 555 cm”! was attributed to the symmetric stretching of

bridging Si-O-Si and bending vibrations of O-Si-O [35] Meanwhile,

O-Si-O bending vibrations were indicated at 469 cm! [36].

The Per was characterized with a specific surface area of 44.81 m2.g

~1 pore sizes of 1.70 nm average pore radius and 2.98 nm average half pore width, and total pore volume of 0.01 cm*.g ~ Ì by some different

methods such as BET, Barret-Joyner-Halenda (BJH), Redushkevich (DR), and Dollimore-Heal (DH), respectively On the other hand, the Na adsorption-desorption isotherm followed type II (defined by IUPAC), implying that the Per was microporous (Fig 2(d)) The Per specific surface area obtained was lower than previous findings, bringing disadvantages for adsorption efficiency [37] Therefore, sur- face modification of Per is necessary for the PC4R adsorptive removal enhancement.

Dubinin-Besides, the Per adsorbents were cubic crystals with each cubic edge

of about 24.64 A determined by the SEM (Fig 3) and the XRD methods.

3.2 Investigation of effect variables on the CTAB adsorption on the Per

3.2.1 Effects of pH and ionic strength

The effects of pH and the ionic strength on the CTAB adsorption on the Per were determined at the same experimental conditions of 5 mg.

mL of the Per dosage, 120 min of the contact time, 0.1 mM of the

CTAB initial concentration, and various pH of 4 - 11 and 100 mM NaCl

(Fig 4(a)), and different strengths of 0 - 100 mM NaCl and pH 9 (Fig 4

Table 1 Chemical composition of the Per adsorbents determined by

the XRF method.

Oxides Chemical composition

(wt%)

SiOz 61.98 AlaOs 37.25

KạO 0.16

CaO 0.46 FeaOs 0.08 CuO 0.07

Si02/Al,03 1.66

Si/Al 1.47

x 2.26

y 0.81

Fig 2 The characterization of the Per measured by: (a) XRF, (b) XRD, (c) FT-IR, and (d) BET methods.

Fig 3 The Per morphology was imagined by the SEM method with different magnifications of: (a) 5 x 10°, and (b) 1 x 10°.

(b)), respectively.

As shown in Fig 4(a), the CTAB adsorption performance on the Per

was dramatically raised from about (19.26 + 4.98) to (53.89 + 3.28)%

with the pH increment from 2 - 9, then kept relatively stable with

continuous pH increment It should be noted that the Per surface charge

density depended on pH, although the Per was negative charge at a large

PH range [38] On the other hand, the CTAB was ever positively charged

at all pH due to -N*(CH3)3 presence At acidic conditions, the Per was

less negatively charged due to more -OH$ groups generated from

orig-inal -OH functional groups of the Per [39] Also, the Per could be partly

dissolved in acidic conditions [40] As a result, less cationic CTAB

adsorbed onto the Per surface due to electrostatic repulsions Whereas,

at basic conditions, the Per was more negatively charged due to the original -OH functional groups of the Per deprotonated to form more -O groups, promoting the CTAB adsorption due to electrostatic attrac- tions [39] Therefore, pH 9 was chosen to optimize the CTAB adsorption

Fig 4 The CTAB adsorption performances on the Per at various: (a) pH, and (b) the ionic strengths.

on the Per due to the maximum CTAB performance achievement of

nearly 53.89%.

The CTAB adsorption performance enhanced remarkably from

approximately (46.36 + 3.16) to (75.66 + 7.25)% while the ionic

strength increased from 0 - 1 mM NaCl, then slightly moved down with

continuously increasing ionic strength until 200 mM NaCl (Fig 4(b)) It

implies the contribution of hydrophobic interactions on the CTAB

adsorption process besides the electrostatic attractions Following the

electrolyte shielding effect, two phenomena were proposed with higher

NaCl concentrations [41,42] Firstly, electrolyte ions impulsed the

hy-drophobic interactions established among long hyhy-drophobic tails of the

CTAB molecules Secondly, the electrolyte ions obstructed the

electro-static attractions between the positively charged CTAB heads and the

Per negative charges.

3.2.2 CTAB adsorption isotherm

The CTAB adsorption isotherms on the Per adsorbents were clarified

at various experimental conditions of pH 9, 1 mM NaCl, 5 mg.mL~ of

the Per dosage, contact time of 120 min with the CTAB initial

concen-tration from 0.01 to 10 mM.

It was investigated that the CTAB adsorption capacity increased from

about (0.0019 + 0.0001) to (0.16 + 0.05) mg.g ~ Ì with arising the

initial CTAB concentration from 0.01 — 100 mM It could be explained by

Langmuir model with a lower correlation efficiency of 0.6670 (Fig 5).

Therefore, it affirms to form multiple adsorbed layers of the CTAB on the Per surface In addition, the CTAB molecules were adsorbed on the Per surfaces due to not only electrostatic attractions between the CTAB-Per

but also hydrophobic interactions between the long hydrophobic tails

[20] Moreover, the CTAB adsorbed layer number was determined to be approximately (2.54 + 0.29) by the Freundlich model On the other hand, a maximum CTAB adsorption capacity of approximately (0.18 +

0.04) mg.g ~ Ì extrapolated by Langmuir isotherm was nearly close to of the experimental value of (0.16 + 0.05) mg.g ~ †,

The experimental conditions for Per surface modification were

optimized and fixed for further study as of pH 9, 1 mM NaCl, 5 mg.mLÌ

of Per dosage, 120 min of the contact time, and 10 mM of the CTAB initial concentration.

V.L Dang et al.

3.3 Investigation of effective conditions on the PC4R removal using

CTAB@Per adsorbents

3.3.1 pH effect

The pH effect on the PC4R removal using the Per adsorbents without

and with surface modification by the CTAB adsorption was investigated

at various experimental conditions of the pH range from 2 - 11, 1 mM

NaCl, 5 mg.mL"! of the Per dosage, 120 min of the contact time, and 20

mg.L ~ Ì of the PC4R initial concentration.

Fig 6 shows that the PC4R removal efficiencies were more

notice-ably obtained with the Per surface modification than without the Per

modification at all pH ranges The PC4R removal increased almost

twofold from nearly (53.23 + 5.39) to (90.06 + 3.88)% corresponding

with using the Per and the CTAB@Per adsorbents at pH 4 It reveals the

highly adsorptive potential of the modified surface adsorbents on the

PC4R removal from aqueous media.

It should be noted that the PC4R charge density was also dependent

on protonation of the -N = N- and -OH groups although the PC4R

molecule was always negatively charged in the investigated pH range of

2 — 11 due to its acid dissociation constants of 2.9 (pKa) and 11.38

(pKaz) [46] With CTAB modified Per surface, the PC4R removal

effi-ciency decreased from approximately (90.06 + 3.88) to (74.58 +

1.50)% while pH decreased from 4 - 2 (Fig 6) The reason could be that

more -N=(H)N‘- and -OH3appropriately protonated from the -N =

N-and -OH groups of the PC4R molecule repulsed the amine group

-N*(CH3)3 of the cationic CTAB while pH was lower than pKại of the

PC4R [47,48] On the other hand, the larger number of the CTAB

mol-ecules was adsorbed on the Per surfaces (investigated above), and the

PC4R molecule became more negatively charged due to more

-O-generated from -OH while the pH changed from 4 to 11 [47] It should

be supposed that the result in an increment of the PC4R removal is due to

more electrostatic attractions between the adsorbed CTAB and the PC4R

with the pH increment of 4 - 11 Oppositely, the experimental data

showed that the PC4R removal efficiency declined from about (90.06 +

3.88) to (66.61 + 3.17)% (Fig 6) It suggested the contribution of other

extramolecular interactions between the PC4R molecules on the

adsor-bent surfaces The cause of this phenomenon could be that less -OH3 and

more -OH or -O— were formed in the PC4R molecules with pH increment,

reducing hydrogen bondings between -OH undissociated or dipole-ion

attractions between -N = N- and -OH$, and enhancing more

re-pulsions between -O and -N = N- between the PC4R molecules [47].

After surface modification with CTAB, interactions between the Per

adsorbents and the PC4R were enhanced by more -OH group

dissocia-tion and protonadissocia-tion to generate -O” and -OH3 groups [47,48].

Fig 6 The PC4R removal efficiencies on the Per adsorbents: without (black)

and with the surface modification by the CTAB adsorption (grey) at

various pHs.

Journal of Molecular Structure 1304 (2024) 137619

Therefore, the PC4R strongly repulsed the Per Especially, the PC4R

positive charge density was more enhanced due to more

-N=(H)N'-formations while the pH was lower than pKại of the PC4R [48] As a

result, the PC4R removal efficiency reached a maximum of mately (53.23 + 5.39)% at pH 4 and correspondingly decreased to about (4.46 + 2.50)% and nearly (0.99 + 0.40)% while pH was greater and lower than 4 (Fig 6).

approxi-3.3.2 Ionic strength effect

The ionic strength effect on the PC4R removal on the Per adsorbents without and with surface modification by the CTAB was investigated at various experimental conditions of the NaCl range from 0 - 150 mM

NaCl, pH 4, 5 mg.mL~! of the Per dosage, 120 min of the contact time, and 20 mg.L ~ ! of the PC4R initial concentration.

Fig 7 shows that the PC4R removal efficiency using the CTAB@Per adsorbents rose from approximately (80.82 + 1.76) to (95.12 + 0.61)% while the NaCl concentration increased from 0 to 10 mM, implying that the important role of the non-electrostatic interactions such as dipole- ion bondings among the PC4R molecules (mentioned above) More- over, the PC4R adsorptive removal efficiency was slightly reduced nearly by 10% with a 15-fold increment of the NaCl concentration from

10 to 150 mM, suggesting the electrostatic attractions declined due to the electrolyte ion shielding effect (Fig 7) [49] The optimal ionic strength was 10 mM NaCl due to the highest achievement of the PC4R adsorption performance with a low standard deviation Conclusively, the PC4R adsorption process on the CTAB@Per surfaces was ably gov- erned by the electrostatic, dipole-ion interactions and hydrogen bondings.

3.3.3 Effects of the Per dosage and contact time

The effects of the Per dosage and the contact time on the PC4R removal were performed at various experimental conditions of pH 4, 10

mM NaCl, 20 mg.L 1 of the PC4R initial concentration, the Per dosage range of 1-8 mg.mL"! (Fig 8(a)), and 0 - 2 h of the contact time (Fig 8

@®)).

The Per dosage noticeably changed 6-fold from 1 to 6 mg.mL"},

attributing more available active Per surface sites for the CTAB adsorption Correspondingly, more the PC4R adsorbed onto the CTAB@Per as well as the PC4R adsorption performance was attained from (62.48 + 3.34) to (91.73 + 3.09)% (Fig 8) Whereas, the PC4R solution was immediately discolored with nearly 90.07% of the PC4R removal efficiency as soon as the mixing event It implies that strong interactions between the PC4R and the CTAB@Per surfaces occurred An

Fig 8 The PC4R removal efficiencies using the CTAB@Per adsorbents at various conditions of: (a) the Per dosage, and (b) the contact time.

equilibrium of the PC4R adsorption fast reached after 15 min of the

contact time.

3.4 PC4R adsorption isotherms on the CTAB@Per adsorbents

To better understand the PC4R adsorption mechanism, the

adsorp-tion isotherms were fitted with two general models including Langmuir,

and Freundlich The fitting parameters were listed in Table 2.

The separation dimensionless factors, Rị of 0.11 - 0.93 were in the

range of 0 - 1, indicating that the PC4R adsorption was favorable

(Table 2) [16] On the other hand, the coefficient, 1/n of 0.35 was close

to zero, implying that the adsorbent surface was heterogenic [50] The

PC4R adsorption was relatively better fitted with the Freundlich

isotherm with a larger correlation efficiency of 0.8888 than the

Lang-muir isotherm with a smaller correlation efficiency of 0.8402 (Fig 9).

Accordingly, it proposes that PC4R adsorbed layers on the modified

adsorbents were multiple [51] On the other hand, the PC4R adsorbed

layer number, n of approximately 2.84 was extrapolated by the

Freundlich isotherm model (Table 2) Additionally, a maximum PC4R

adsorption capacity of 15.470 mg.g~ Ì was extrapolated from Langmuir

isotherm On the other hand, the PC4R adsorption performance by the

use of the CTAB@Per adsorbents was found to be greater than some

common adsorbents (Table 3) It implies that cationic surfactant CTAB

applied as a surface modifier created more active sites for the PC4R

removal from aqueous media.

3.5 PC4R adsorption kinetics on the CTAB@Per

The PC4R adsorption kinetics on the CTAB@Per were fitted by the

pseudo-first and pseudo-second models under the fixed conditions of pH

4, 10 mM NaCl, 6 mg.mL of the Per dosage, 10 mg.L ~ Ì of the PC4R

initial concentration, and the contact time from 0 — 120 min (Table 4).

As depicted in Fig 10, the pseudo-second model achieved a higher

correlation coefficient, R? of 0.9995 which was more suitable for the

PC4R adsorption kinetic than the pseudo-first model with a lower R2 of

0.1648 In addition, the calculated equilibrium adsorption capacity

obtained from the pseudo-second model was better matched with the

(Table 4) It was emphasized that the PC4R adsorption was basically chemisorbed on the CTAB@Per surface [16,53].

3.6 PC4R adsorption mechanism on the CTAB@Per clarified by the

FT-IR measurement

As shown in Fig 11, the symmetric Si-O-Al stretching vibration was

assigned at 651.94 cm”! while the Si-O-Al asymmetric one was pointed out at 694.37 cm”! in the Per spectrum Meanwhile, the stretching vi-

brations of Si-Al-O and Si-O-Si were designated at 549.71 and 1180.44

cm} respectively [54,55].

As a result of cation exchange between metal cation on the Per and

the cation CTAB, the Si-O-metal stretching vibrated at 464.84 cm! in the CTAB spectrum was attributed at 457.13 em Ì in the CTAB@Per

spectrum The Si-OH and C—N* stretching vibrations in the Per and the

CTAB spectra appeared at the same wavenumber of 962.48 cmTM!

slightly shifted to 958.62 cm7! in the CTAB@Per spectrum [54,55].

Also, the presence of the CTAB molecules on the Per surface was

demonstrated by the appearance of a small peak at 3014.74 cmTM!

rep-resenting for the C—NT stretching vibration in the CTAB molecule.

The C—N' stretching vibrated at 962.48 em” in the CTAB spectrum was relocated at 1002.98 cm Ì in the PC4R-adsorbed CTAB@Per spec-

trum [56,57] The -CH; stretching vibrations located at 2848.86 and

2918.30 em in the CTAB spectrum were correspondingly shifted to 2899.01 and 2989.66 cm Ì in the PC4R-adsorbed CTAB@Per spectrum

[58] It implies that the CTAB interacted with the PC4R vice (CH3)3N+

SO3 electrostatic attraction The peaks of -OH stretching vibrations

specified at 1489.05 and 3417.86 cm! in the PC4R spectrum moved to 1475.54 cm Ì and disappeared in the PC4R-adsorbed CTAB@Per spectrum [59] Meanwhile, a sharp peak at 1629.85 cmTM! attributed to

O—H blending vibration in the PC4R molecule was slightly displaced to

be at 1643.35 cm, All changes in the -OH group vibrations, suggesting

that the able hydrogen bonding formation of the -OH groups between

the PC4R molecules Moreover, the wavenumber at 1039.63 cm Ì

rep-resenting the -SO3 stretching vibration in the PC4R molecule was

transferred to 1045.42 cm Ì in the PC4R-adsorbed CTAB@Per

spec-trum The -S = O stretching vibrations revealed at 1143.79 and 1174.65

1

experiment value than that achieved from the pseudo-first model cm ~ were not observed in the PC4R-adsorbed CTAB@Per spectrum

Table 2

The fitting parameters of the PC4R adsorption isotherms on the CTAB@Per.

Isotherms Langmuir Freundlich

Fitting parameter R? KL Qmax R, R? Kr (mạ! 1⁄n n

(Lmg"?) (mg.g~ 1) img 1=)

Value 0.8402 0.015 + 0.005 15.470 + 1.915 0.11 - 0.93 0.8888 1.57 + 0.23 0.35 + 0.04 2.84 + 0.29

Maximum PC4R adsorption capacities using different adsorbents.

Adsorbents Qmax References

(mgg_ ”)

CTAB@Per adsorbents 15.470 This study

Walnut shell-prepared activated carbons 2.0 [52]

Poplar-prepared activated carbons 3.91 [50]

Almond shell-prepared activated carbons 10.752 [18]

Table 4

The parameters of the PC4R adsorption kinetics on the CTAB@Per adsorbents

following the pseudo-first and -second models.

[60-62] These changes in the -SO3 functional groups of the PC4R

molecule demonstrated that the electrostatic attractions were formed

between the PC4R and the adsorbed CTAB on the modified Per surfaces.

On the other hand, the -N = N- stretching vibration located at 1421.54

cm Ì in the PC4R spectrum was absent in the PC4R-adsorbed

CTAB@Per spectrum [63] It was probable that the dipole-ion

in-teractions of -N = N- and -OH3between PC4R molecules.

4 Conclusions

The zeolite, Permutit was modified through the CTAB adsorption and used as an effective adsorbent on the PC4R adsorptive removal from aqueous media The Per characterizations of the cubic crystal, 1.66 of

the SiOz/AlaOa ratio, 44.81 mổ.g ~ 1 of the specific surface area, 1.7 nm

of the average pore radius, and typical bonds of Si-Si, Si-Al, and Si-O-Si were correspondingly determined by the measurements of XRD, XRF, BET, and FT-IR The experimental conditions were optimized to be

O-pH 4, 10 mM NaCl of the ionic strength, 6 mg.mL of the Per dosage,

and 15 min of the contact time The PC4R adsorption was followed by both Langmuir and Freundlich isotherms The multiple adsorbed layers

of the PC4R were formed while 15.48 mg.g ~ Ì of the maximum PC4R

adsorption capacity was obtained on the CTAB@Per surfaces The PC4R adsorption was chemisorption and better fitted with the pseudo-second- order model The electrostatic attractions between the CTAB-PC4R molecules, the dipole-ion interactions, and hydrogen bondings be- tween PC4R molecules primarily controlled the PC4R adsorption pro- cess demonstrated by the FT-IR measurement A nearly 90.06% PC4R adsorptive removal efficiency was significantly achieved by using the

50 40

2 30 D

CRediT authorship contribution statement

Van Long Dang: Data curation, Formal analysis, Funding

acquisi-tion, Investigaacquisi-tion, Methodology, Project administraacquisi-tion, Software,

Validation, Visualization, Writing - original draft, Writing - review &

editing Thu Trang Kieu: Investigation, Software Thi Thu Thao

Nguyen: Investigation, Software Thi Thuy Trang Truong: Data

cura-tion, Formal analysis Duy Thanh Hoang: Investigation Thi Linh Chi

Vu: Investigation Thi Minh Thu Nguyen: Formal analysis, Resources,

Visualization Thanh Son Le: Formal analysis, Resources, Writing —

review & editing Thi Hai Yen Doan: Conceptualization, Data curation,

Funding acquisition, Methodology, Project administration, Supervision,

Validation, Visualization, Writing - original draft, Writing - review &

editing Tien Duc Pham: Conceptualization, Funding acquisition,

Methodology, Supervision, Validation, Visualization, Writing - review

& editing.

Declaration of competing interest

The authors declare that they have no known competing financial

interests or personal relationships that could have appeared to influence

the work reported in this paper.

Data availability

Data will be made available on request.

Acknowledgments

This research has been done under the research project QG.22.17 of

Vietnam National University, Hanoi.

We would like to thank Dr Johan Hunziker, IGEPP, INRAE, Institut

Agro, Univ Rennes, 29260, Ploudaniel, France for the available

com-ments and English check to improve our manuscript.

Supplementary materials

Supplementary material associated with this article can be found, in

the online version, at doi:10.1016/j.molstruc.2024.137619.

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