Nghiên cứu ảnh hưởng của axit humic đến sự di chuyển của một số kim loại nặng trong các đối tượng môi trường

Ket qua cho thay cd the sii dung cot chiia axit humic dang rdn dugc tach tii than biin ciia Viet Nam de tach cac ion Pb^"^, Cu^"^, Zn^"", Cd^'^khdi nudc thai cd mdi trudng axit... Chinh

DAI HOC QU6C GIA HA N O I TRUCJNG DAI HOC KHOA HOC TLf N H I £ N

D^TAI

NGHIEN CUfU ANH HUONG CUA AXIT HUMIC DEN SU Dl

CHUYEN CUA MOT SO KIM LOAI NANG TRONG CAC DOI

TUONG MOI TRUONG

MA SO : QT - 03 - 27

CHU TRI Dfi TAI: PGS.TS Bui Du v Cam

CAC CAN Bp THAM GIA:

-TS Pham Van Tinh -ThS Nguyen Bao Cham

DAI H O C Q U O C GIA HA NO* TRUNG TAM THONG TIN THU VIL' N

or/ ^36

HA NOI 2005

MUC LUC

Trang

Bao cao torn tat

Mddau

Chuong 1 Axit humic va vai tro ciia no trong moi trudng

1.1 Su ton tai ciia axit humic trong lir nhien

1.2 Thanh phan va cau tao ciia axit humic 1.3 Tfnh chat ciia axit humic

1.4 Vai trd cua axit humic trong xii ly moi trudng

Phuang phap phan tich kim loai

Phiurng plidp xdc dinh Ph (H) Phif(/nsi phdp xdc dinli Cd (H) PliU(/Hi^ pluip xdc diidi Cu (//) PhU(my, phdp xdc dinh Zn (H) PhU(my, phdp phdn tich As

Ket qua va thao luan

Nghien cuu kha nang hap giu cua axil humic ddi \'di Ph '

Ni^hicn cuu anh hUony, cua pH den kha ndnsj, hdp •^iil Ph ' Nghien cihi dnh hudng cua thdi i^ian den kha ndn_'^ hap i,'//?'

Nghien ciiu kha nang hap giu cua axil humic \'di Cu^*

Chuong 2

2.1 2.2 2.3 2.4 2.4.1

2.4.2

2.5 2.5.1

3 1.2

3.2

2.1 Nghien ciiu anh hudng cua pH den kha ndn<.^ hdp L;//7

2.2 Nghien diu d/ih hU(hii> chia thdi gian den kha ndng hdp gill

3.3 Kel qua nghien cuu kha nang hap giu' cua axit huinic vdi Zn''

3.1 Nghien ( uu anh hii'chig cua pH den kha ndng hap gift 3.2 Nghien cUu anh huong cua thdi gian den kha nd/i'^ hap ;^iu

3.4 Nghien cuu kha nang hap giu cua axil humic \ di Cch'

4.1 Nghien cuu anh hiuhig c ua pH den kha ndng hdp giil' 4.2 Nghien eu'u anh hiuhig cua thdi gian den kha ndng hap giil'

^.5 Ket qua nghien cuu kha nang hap giucua axil huinic \'di Asen

5.1 Kel qua nghien cuu kha ndng hdp giU As (11/) cua axil humic

5.2 5.^

5.4 3.6 3.7

Ket qua nghien cii'ii kha ndng hap gitl' As (\'} hoi axil hiiinu Kel qua nghien cuu kha ndng hap ^^iu As M / hoi a\ii huniu khi CO nidi cua Fe''

Nghien eu'u kha ndng hdp giil' A.\ cua sal liunial

Nghien cuu anh hudng cua mot so dien 1\ den qua trinii hap giu" Cch*

Tiich cac ion kim loai tren cot chua axil hunuc

B A O C A O TOM T A T Bt T A I

• l.Ten de t a i ; Nghien cAu dnh huang cua axit humic den su di chuyen ctia

mot so kim loa nang trong cdc doi tuang moi tru&ng

2 M a s o ; QT-03.27

3.Chu tri de tai: Biii Duy Cam

4.Cac can bo tham gia:

-TS Pham Vdn Tinh -ThS Nguyen Bdo Cham

5 Muc tieu va noi dung nghien cihi :

- Nghien cihi kha nang phan ling cua axit humic vdi cac kim loai nang trong moi truang nu6c

- Nghien ciJu cac yeu to anh hudng den kha nang hap phii cac ion kim loai nang ciia axit humic

- Nghien cihi kha nang sir dung axit humic lam chat hap phii tach cac ion kim loai nang ra khoi dung dich nudc

6 Cac ket qua dat duac

6.1 Ket qua khoa hoc

- Ve khd ndng phdn dng cua axit humic vai cdc kim loai nang trong moi trudng nuac:

La mot axit hiJu ca chua trong phan tir nhi^u nhom chiic hoat dong nhu cacboxyl, phenolic hydroxyl, nito di vong, amino tham nen axit humic la mot hgp chat rat hoat dong ve mat hoa hoc No co kha nang tham gia phan ling trao doi cation, tao ket tiia, tao phiic vdi nhieu hap chat vo ca va hiJu ca Axit humic cd the tao phiic tan hoac khdng tan vdi nhi6u ion kim loai nang

va phdng xa.Vi vay, trong cac nguon nudc axit humic dugc xem la tac nhan ldi keo va phan tan cac kim loai nang d trong cac nguon nudc Kha nang

1

phan ling cua axit humic vdi cac ion kim loai nang Pb^"", Cu""^, Zn^"", Cd^"", As^"", As^^ da dugc nghien ciiu Ket qua cho thay axit humic r^n cd the hap phu kha manh cac ion kim loai nay

- Ve cdc yeu to dnh huang den khd ndng hdp phu cua axit humic

Mot so yeu to' da dugc nghien ctiu la pH dung dich, thdi gian phan ling, sir

cd mat ciia chat dien ly Trong viing pH tii 1 den 6, neu pH cang tang thi hieu suat hap phu cang tang.Tuy nhien viing pH thfch hgp nhat la 4,5 den 5,5 va khoang 70% den 98% lugng kim loai trong dung dich cd the dugc hap phu 0

viing pH cao hon dt xuat hien sir thuy phan ciia cac ion kim loai nay Thdi

gian phan ling dugc nghien ciiu tir 20 den 360 phiit Sau 20 phiit hieu suat hap phu da dat tii 50% den 70% doi vdi ca hai loai axit Cac chat dien ly hau nhu khdng anh hudng den phan ling cua axit

- Ve khd ndng su diojg axit humic de tdch kim loai nang khoi dung dich nUdc

Kha nang sir dung cot trao doi chiia humic dang r^n da dugc nghien ciiu Ket qua cho thay cd the sii dung cot chiia axit humic dang rdn dugc tach tii than biin ciia Viet Nam de tach cac ion Pb^"^, Cu^"^, Zn^"", Cd^'^khdi nudc thai

cd mdi trudng axit Hieu suat tach d pH = 4,6 - 4,8 dat 98% B^ng phuang phap nay cd the lam giam ndng do cua cac ion nay tii 20mg/l xudng cdn 0,004mgA-

- Ve cong trinh dd cong bd: Da cong bd 01 bai bao trong tap chf Phan

tfch Ly Hoa sinh

6.2 Ket qua dao tao

- 01 Thgc sT Moi truang

- 01 Cunhdn Hod hpc

7 Tinh hinh su dung kinh phi cua de tai:

- Kinh phi dugc cap : 20.000.000 d

Kinh phi da sir dung

Van phdng pham

Thue khoan chuyen mdn

Vat tu hoa chat

Quan ly hanh chinh

Hdi nghi, hgi thao, cdng tac phi

1.000.000 d 7.000.000 d 10.000.000 d 800.000 d 2.200.000 d

XAC NHAN CUA BAN CHU NHlfiM

KHOA HOA HOC

CHU TRI D £ T A I

P / H T^ ~IM^^%' jM^u.' PUf PGS.TS Bui Duy Cam

XAC NHAN CUA TRUCTNG DAI HOC KHOA HOC TU NHIEN

KT.HIEU TRUONG PHO HIEU TRUONG

GS.TS Trdn Nghi

Dr Pham van Tinh

MS Nguyen Bao Cham

5 Purpose and contents of project:

- To research the reaction of humic acid with some heavy metals in solution

- To determine the factors influenced on adsorption capacity of heavy metal ions by humic acid

- To use solid humic acid for decontaminating polluted water by heavy metals

6 Activities and main results :

- Humic acid - the fraction of humic substances that is not soluble in water under acidic condition (pH < 2 ) but is soluble at higher pH value

- Humic acids are used most effectively in particular in the stage subsequent to chemical treatment of water Due to their outstanding properties of adsorption of liphophlic substances, their high cation exchange capacity, their ability to form hardly soluble complexes with polyvalence cations and heavy metals and their high electron exchange capacity, hmic

acids are ideal as sorption medium for a number of water impurities and especially for heavy metals and liphophlic substances

In our works, we prepaired two kindes of humic acid One is from peat of Vietnam, one is comercial product of Wako company in Japan and compared their adsorption properties , The complexation of humic acid with cations Pb^"^, Cu^"^, Zn^"^, Cd^"^, As^"", As^ was studied.The adsorption capacity of humic acid depends on pH value of solution and increases with increase of

pH (range from 1 to 6 ) After 20 minutes, about 70% to 98% these ions absorbed on solid humic acid at pH = 4.5 - 5.0

We have shown that humic acid packed column 9(0.15 - 0.45 mm particle diameter) can remove 98% these ions at pH = 4.6- 4.8 The extraction effiences were highest for Pb^"^, Cu^"^and lower for Zn^"^, Cd^"^ Arsenic was not absorbed by humic acid

MO DAU

Cung vdi su gia tang dan sd va phat trien khoa hgc cdng nghe ma nhu cau nudc sinh hoat cua cac qudc gia ngay cang tang manh Song, hien tai van de d nhilm cac ngudn nudc (nudc ng^m, nudc be mat, nudc sinh hoat, nudc thai) cang cd xu hudng gia lang d nhi6u nudc, trong dd cd Viet Nam

Tha'y dugc tam quan trgng cua viec khai thac, bao ve va sii dung hgp ly ngudn

nudc ma nha nudc ta da dua ra nhieu chinh sach vt van dt nay nhi6u hgi thao qudc

gia va qudc te to chiic tai Viet Nam da de cap den viec phan tfch danh gia chat lugng cac ngudn nudc, dua ra cac cdng nghe xir ly nudc d nhilm

Trong sd cac chat gay d nhilm, kim loai nang (trong dd cd As) la ddi tugng dugc quan tam dac biet Theo cac sd lieu da cdng bd thi d mot sd nai cua Viet Nam , ham lugng kim loai nang trong cac ngudn nudc da vugt qua gidi han cho phep Chinh

vi vay, viec xii ly tach kim loai nang ra khdi cac ngudn nudc la mot nhu cau can thiet

Trong dl tai nay, chiing tdi nghien ciiu phan ling ciia axit humic vdi cac kim loai Pb, Cu, Zn, Cd, As va kha nang sii dung nd de tach kim loai nang ra khdi cac nguon nudc khac nhau

Chuong I AXIT HUMIC VA VAI TRO CUA NO TRONG MOI TRUCtNG

l.l.Sir ton tai cua axit humic trong tu nhien

Axit humic la mot axit hiiu ca yeu.Nd la hgp chat cd phan tu lugng Idn, cd chiia nhilu nhdm tham.Nd la chat kem tan, thudng tdn tai dudi dang rdn d trong nudc

va da't.Trong tu nhien, axit humic tdn tai nhilu d trong cac loai than va bun Song, chi

cd than mim la chiia axit humic vdi ham lugng ldn(tir 30-90% tuy thugc vao md than ) Than biin, biin, cac chat humat cung chiia mot lugng dang ke axit humic (tii 5-60% tuy thudc vao do tuoi cua than)

O Viet Nam, cd the tim thay than biin d hau het cac tinh tii B^c vao Nam nhu Quang Ninh, VTnh Phiic, Ha Tay, Ha Nam, Bdc Ninh, Bac Giang, Thanh Hoa, Nghe

An, Hue va dac biet cd rat nhilu d viing ddng bang sdng Cuu Long Tdng trii lugng

than bun ciia Viet Nam la khoang 1.033.355.000 m\

O trong nudc ngam, cac chat humic thudng tdn tai vdi ndng do tir 10 ppb den

100 ppm

1.2.Thanh phan va cau tao cua axit humic

Axit humic dugc hinh thanh tii qua trinh phan huy ddng thuc vat Tuy thuoc vao dilu kien chuyen hoa va ban chat cua ddng thuc vat ma qua trinh chuyen hoa se tao nen cac axit humic cd ca'u tnic, trgng lugng phan tu va thanh phan hoa hgc khac nhau

Axit humic cd khdi lugng phan tu tii 2.000-600.000 dan vi caebon Tuy thugc vao nguon gdc ma axit humic cd thanh phan khac nhau Tuy nhien, thanh phan chfnh ciia axit humic la cac nguyen td C, H, O, N va mdt lugng nhd cac nguyen td khac nhu S, P,

Al, Fe Ham lugng cac nguyen td chu yeu nay thudng chiem ty le nhu sau:

Ham lugng C : tii 55%-65%

Ham lugng H : til 3%-10%

Ham lugng O : tii 25%-35%

Ham lugng N:tir6%-7%

Ham lugng cac nguyen td khac : tu 6%-7%

Cung cSn phan biet vdi axit fuvic Day la axit cd khdi lugng phan tir tir 2.000 don vi caebon va cd cau tnic phan tir gan tuang tu axit humic

500-Axit humic cd ca'u tao khdng xac dinh Theo cac ke't qua nghien ciiu gan day thi axit humic la mdt hgp chat tham cd c^u tnic polyme vdi nhilu lien ket giiia cac nhdm tham Cac hgp chat khac nhau lien ke't trong axit humic la amino axit, amino dudng, peptit axit ali phatic.Axit humic cd chiia cac nhdm chiic khac nhau nhu -COOH, phenol, ali phatic, enolic hydroxyl, C=0 Axit humic la mdt td hgp cac phan tir hinh thanh nhilu sgi dai d pH tha'p va cau tnic linh ddng cd nhilu Id hdng d pH cao Chfnh cac Id hdng nay cd the giii va hap phu cac cha't vd ca va huu ca mang dien tfch trai dau

Phan tir axit humic cd dang polyme, trong dd cd chiia nhiing hgp chat nhan tham kieu phenol va cac hgp cha't chiia nita dang vdng va di vdng (indol; purin; primidin) va cac axit amin Cac hgp chat tham tao ra nhan tham ciia axit Humic Cac cSu ndi nay cd the la nhOng phan tir rieng biet ( - 0 - ) hoac la nhdm ( -NH2-; -CH2-) cung cd the lien ket true tiep qua nguyen tu Caebon (-C-) [1,2]

Trong cau tao ciia axit humic cd :

- Nhdn tham khi oxy hoa axit humic bdi HNO3, kilm hoac KMn04 ngudi ta

thay xuat hien nhiing nhan tham Dd la nhung dan xuat cua phenol, quinon va axit benzoic Theo W Conell cau tnic mdt sd nhdm nhu sau:

Khi thuy phan axit humic bdi mdt axit vd ca thi cd chirng mdt nua nguyen tir nita chuyen vao dung dich Dd la nhirng amit, mono hoac diamino axit Mot sd tac gia cdn tim thay ca nhung axit amin cd nhan tham purin, primidin, indol

- Nhom dinh chitc cua axit humic

Trong axit humic cd nhiing nhdm chiic dien hinh la: cacboxyl ( -COOH ), rugu ( -OH ), metocxyl ( -OCH3), cacbonyl(-C=0), phenol ( -OH ) O mach ben cd chiia

ca nhdm cd ndi ddi ( -C=CH-) Nhd cac phuang phap hien dai, cac nha khoa hgc xac dinh dugc axit humic cd 3 - 4 nhdm cacboxyl va tir 3 - 6 nhdm -OH ciia rugu va phenol

Sa do cau tnic phan tu axit humic cua Dragunov va cdng tac vien nhu sau:

CeHnOs

HO

- Cdc nhom chitc ldm cho axit humic co khd ndng tao phiic la: cacboxyl,

phenolic hydroxyl, nita di vdng, ali phatic va cac amino tham Axit humic cd the tao phiic vdi ion kim Igai giira hai nhdm COO" va OH', giira hai nhdm COO hoac mot nhdm COO'

1.3 Tinh chat cua axit humic

Axit humic khdng tan trong nudc cd mdi trudng pH < 2 nhung tan dugc trong kilm va mdt sd dung mdi hiru ca (dimetyl fomamit, dimetyl sunfoxit)

Axit humic dugc tach ra tuf than bun la chat ket tinh mau den, sang dng anh, khd

bi nhiet phan ngay ca khi nung ndng d 200°C

Nhu da neu trong phSn tren, vi trong phan tir cd chiia nhdm cacboxyl va phenol nen axit humic dugc xep vao loai axit huu ca yeu Cac nhdm chiia axit trong phan tir humic cd cudng do axit khac nhau, ke ca cung loai caboxyl hoac phenol nhung neu d

vi tri khac nhau se cd cudng do khac nhau Gia tri pKa ciia nhdm caboxyl nam trong khoang tir 4 - 6, cdn pKa cua nhdm phenol cd gia tri tir 9 - 11

Su cd mat ciia cac nhan tham vdi cac electron p linh ddng va cac nhdm chiic khac nhau lam cho axit humic cd kha nang thiic hien phan ling trao ddi ion, tao phiic

va oxyhoa- khu Khi trao ddi cation, cac vi tri tren phan tir humic gan nhu dugc lap d^y cation hydro

Cac cha't humic gan nhu hoan toan tfch dien am do cd chiia mot lugng Idn cac nhdm chiic cacboxylic, phenolic Do qua trinh hydrat hoa cac nhdm tich dien va luc day tinh dien ma cac chat humic hoa tan d trong nudc dugc phan bd rgng han do su thay ddi dilu kien mdi trudng Axit humic dugc xem la cau tir quan trgng trong dat va nudc'

Dua vao ke't qua thuc nghiem nghien ciiu tuang tac cua axit humic vdi cac cation kim loai nhu Cu^"^, AP"", Zn^"^, Mn^"^, Fe^"" cac tac gia da ket luan axit humic la chat

cd kha nang tao phiic manh vdi ion kim loai.Trong phan ling, cac cation kim loai da the nguyen tir hydro cua cac nhdm chiic trong phan tir axit humic de hinh thanh nen phiic chat [ 2 , 4 ]

Phan ling giira axit humic vdi cation kim loai cd the tao nen hgp chat vdi cac kieu lien ke't khac nhau

- Lien ket ion: tao nen cac mudi di cue humat cua cac cation kim loai hoa tri

- Lien ket phdi tri: Tao thanh cac mudi phiic Cd the cd 2 loai phiic: Phiic

thudng (neu trong phiic cd 2 loai lien ket ion va lien ket cdng hoa tri) phiic ngi (neu trong phiic cd 2 loai lien ket ion va kieu lien ket phdi tri, trong dd phan tir hiiu ca la phdi ttr cdn Me la cha't tao phiic)

- Lien ket phdn tU: Tao nen khi axit humic tuang tac vdi cac oxyt R2O3 hoac

khoang set Vai trd ciia axit humic trong kieu lien ke't nay gidng nhu chat ket dfnh, lien ket cac hat khoang trong da't lai vdi nhau

Khi diing axit humic de ket tua dinh lugng kim loai thi tuang tac ciia axit humic vdi kim loai la tuang tac hoa hgc chii khdng phai la hap phu vat ly thdng thudng pH cua mdi trudng cd anh hudng manh de'n do bin cua phiic

Pandey A.K va cac cdng su [23] cho thay: axit humic vdi nhdm chiic hydroxyl, phenoxyl, cacbonyl cd the tao thanh hgp chat phdi trf vdi kim loai Nghien ciiu su tao phiic d pH= 3,5 cho tha'y hang sd bin (logk) cua phiic dugc tao hinh thanh giua axit humic va cac kim loai khac nhau giam theo trat tu sau: Cu > Fe > Pb > Ni > Co > Ca >

Cd > Zn > Mn > Mg Ngoai pH mdi trudng, kha nang trao ddi cation, ban kfnh phan tir va dien tfch bl mat phan tir ciia axit humic cung anh hudng den do bin ciia phirc Viec xac dinh hang sd bin ciia phiic giiia axit humic vdi cac nguyen td: Be, Ca,

Sc, V, Cr, Mn, Fe, Co, Zn, Ga, Sr, Y, Ba, Ce, Eu, Gd, Tm, Yb, Lu, cho thay nhung ion

cd dien tfch Idn, ban kfnh ion nhd se tao phiic bin han Vj trf tao phiic la nhdm cacboxylat [ 3 ]

1.4 Vai tro cua axit humic trong xu ly moi trudng

Cac nha khoa hgc mdi trudng tir lau da rat quan tam den cac cha't humic vi phan ling ciia nd vdi dat va nhung chat d nhilm trong nudc cung nhu anh hudng ciia nd de'n qua trinh xir ly Song, nhiing cdng bd vl ling dung thuc te ciia cac chat humic trong cdng nghe mdi trudng cdn chua nhilu.Hau het cac nha khoa hgc da sir dung cac chat humat de tach kim loai khdi nudc hoac tach kim loai nang trong dat.Phan ling giua cac chat humic vdi chat thai hoa hgc dgc hai se xay ra khi hoa chat nay dugc thai xudng dat.Yeu td chii yeu dugc quan tam trong phan ung ciia axit humic vdi chat thai hoa chat la do tan ciia cac vat lieu humic Cac chat humic dich chuyen trong mdi trudng vdi mdt lugng Idn la do tiep xiic vdi chat thai kiem vf du nudc thai tach luu huynh tir

11

san ph^m dau md Cac cha't humic trong dung dich cd the dugc ke't tiia khi tie'p xiic vdi nudc thai cd mdi trudng axit hoac chiia ion kim loai da hoa tri

Kha nang phan ling tao phiic chelat vdi ion kim loai ciia axit humic da dugc nhieu tac gia nghien ciiu Phan ling nay phu thugc vao cac yeu td sau: Ban chat cac cha't humic; ban cha't ciia da't va mdi trudng nudc nhu do axit, kilm; kha nang oxyhoa-khir; su cd mat ciia cac cha't canh tranh (vi du xyanua canh tranh vdi humic ddi vdi ion kim loai).Trong mot sd trudng hgp, axit humic cdn ngan can phan ling tao ke't tua cua kim loai vdi mot sd anion nhu cacbonat, hydroxyt, sunfua.Axit humic cd the lam tang

do tan ciia thuy ngan len 1000 lan Nhu vay, neu dung axit humic de tach kim loai ra khdi nudc bang phuang phap ke't tiia trong trudng hgp nay se khdng cd hieu qua

Mot anh hudng khac cua axit humic ddi vdi kim loai la phan ling oxyhoa-khir Phan ling nay xay ra theo 2 each:

Axit humic ddng vai trd la mot tac nhan khir vdi the khir la E^= 0,7 V gdn

bang the khir cua Fe(III)

Axit humic lam bin viing cac cation kim loai cd tfnh khir trong dung dich bang phan ling tao phiic chelat va do vay lam tang kha nang khir ciia cac oxoanion ( nhu Cr07^' ,Mo04 ^')

Su dich chuyen, phan ling ciia cac hgp chat hiru ca khdng phan cue trong mdi trudng nudc chiu anh hudng cua cac chat humic tan, keo hoac khdng tan trong dd Do kha nang phan ling dugc vdi nhilu kim loai va cac chat hiru ca nen axit humic la mot trong nhiing tac nhan van chuyen kim loai nang d trong cac ngudn nudc ngam va nudc

be mat Axit humic vi the da dugc nghien ciiu sir dung trong cdng nghe xir ly mdi trudng de tach loai cac cha't ddc vd ca va hiiu ca Trong cdng nghe mdi trudng, axit humic dugc ling dung theo mdt so hudng chu ye'u sau day:

- Trung hoa nudc thai axit

- Tach kim loai nang bang tao phiic chelat hoac ket tiia humat khdng tan

- Tach cac anion nhu photphat, xyanua va cac anion hiru ca bang tao phirc vdi phdi tir hdn hgp

- Ha'p phu cac cha't ddc hiiu ca de lam tang kha nang xir ly ngudn nudc thai bang phuang phap sinh hgc

- Tach cac cha't la lirng bang ke't tua hoac lam ndi len

Vermeer va cong su da nghien ciiu kha nang hap phu Cd len hdn hgp axit humic

va hematit Ket qua cho tha'y, hieu qua tach Cd td't hon so vdi viec dung rieng re cac cha't humic hoac hematit Gia tri pH cua mdi trudng cd anh hudng de'n su hap phu

Do phan ling giua axit humic mang dien am va oxyt sat mang dien duang ma su hap phu ion kim loai len axit humic (trong hdn hgp) se giam di so vdi axit humic tinh khiet Vi the tdng ha'p phu dd'i vdi kim loai len hdn hgp se nhd han so vdi du doan theo quy tac cdng tfnh Trong trudng hgp nay, ion kim loai cd ai lire vdi axit humic ro ret hon so vdi oxyt khoang Ngugc lai, tdng ha'p phu kim loai se Idn han trong trudng hgp ion kim loai cd ai luc ddi vdi oxyt khoang manh han so vdi axit humic

Axit humic thd vdi kfch thudc hat 0,1 - 0,6mm cd the dugc diing nhu la mdt tac nhan chiet dang ran de xir ly nudc thai cd chiia Pb^^ Zn^^ Ni^^ Ca^^ Sn^^ Cd^% As^\ Mg^"" trong mdi trudng axit Hang sd bin dilu kien (logK) ciia phirc kim loai - humic (trong than mim) cd gia tri tir 4,6 - 5,5 Hap dung tfch theo mg kim loai/g axit humic cua cdt la 0,15 (ddi vdi Ag"*^) va 2,22 (dd'i vdi Pb^"^) Hieu qua tach ciia cdt chira axit humic la cao nhat dd'i vdi Pb^"", Cu^"^, Sn^"", va thap nhat ddi vdi Mg^"^

Axit humic va nhiing san pham the ciia nd da dugc sir dung de tach loai kim loai ddc khdi nudc thai Axit humic la chat cd hieu qua de xir ly nudc bang phuang phap hoa hgc sau khi thuc hien phuang phap ke't tiia hydroxyt Viec them axit humic se lam tang qua trinh ke't tua kim loai Bang phuang phap nay cd the lam giam ndng do kim loai trong nudc thai thap han 0,03mg/l Hieu qua nha't ciia phuang phap nay la

ddi vdi Pb'^ H g ' \ Cd'\ Cu-^ Zxi^\ Ni'^ Cr^^

Do tfnh chat hap phu, kha nang trao ddi cation, kha nang tao phiic khd tan vdi cation da hoa tri va cation kim loai nang, kha nang trao ddi ciia electron cao ma axit humic la chat hap phu ly tudng cac tap chat trong nudc De xir ly nudc ngam, cd the bam axit humic long vao kenh nudc ngam

Axit humic cd do tan giam d pH thap va cd do tan rat thap d pH = 2 Do vay, axit humic rat cd gia tri de lam sach nudc thai cd mdi trudng axit Axit humic ddng mot vai trd quan trgng trong chu trinh dia hoa cung nhu dac tinh ciia nhilu cau tir hoa

13

hgc trong mdi trudng bien Axit humic cd the tao phiic vdi cation kim loai va dilu nay dan den su di chuyen va phan bd lai cac kim loai giiia nudc va tram tich

Tir axit humic ngudi ta cd the che tao chat hap phu HUMASORB Chat nay rat

cd hieu qua de tach cac kim loai nang, kim loai kiem va phdng xa, cac hgp chat huu

ca Khi dung 0,2gam chaft HUMASORB vdi thdi gian phan ling trong 2 gid d 25°C da ha'p phu dugc 98% Ce, Pb trong 25ml cd ndng do Ce, Pb ban dau la 200 ppm Ca che tach d day gom ca 2 loai: trao ddi ion va tao phiic vdng cang

CHLfONG 2 - THlTC NGHlfiM

2.1 DUNG CU

- Cdc thiiy tinh, pipet, buret ,binh dinh miic ,binh tam giac cac loai

- May do pH vdi dien cue thuy tinh td hgp: Denver - BASIC

- May do quang: Jen way 6400 spectrophotometer

- May ha'p thu nguyen tir: GA900

- can phan tich (do chfnh xac ± 0,2mg)

2.2 VAT LIEU

De tie'n hanh nghien ciiu, chiing tdi da dung hai loai axit humic: mot loai la axil humic thuang mai ciia hang Wako - Nhat Ban (dugc ky hieu la axit HAI) va mdt loai dugc tach tir than biin cua Viet Nam (dugc ky hieu la axit HA2)

Tdch vd tinh che axit humic tit than bun Viet Nam

- Than biin dugc xir ly ban dau vdi axft, hoa tan trong kilm rdi dugc ke't tiia lai

bang axft Lgc, rira - lap lai cac qua trinh hoa tan trong kiem, ket tiia lai vdi axft Lgc, rira tdi pH ^ 2 vai lan Hong khd, cudi ciing say d nhiet do nhd han 80"C

- Xac dinh ham lugng axft humic theo phuang phap [7]

Giii cac san pham axft humic trong Ig kfn Trudc khi dung,dugc nghiln nhd tdi kfch thudc cdn thiet

• 2.3, HOA CHAT VA THUOC THU^

Cac hda cha't dugc diing diu la loai tinh khiet phan tfch: PA hoac AR

Pb(N03)2.H20, Zn(N03)2.H20, CdCl2.2,5H20 , Cu(N03)2.H20, AS2O3

CH3COOH, HNO3, HCl, NaOH, dung dich dem axetat pH4,3; 5 , chi thi xylen da cam, dung dich nudc brom, hydrazyl sunfat - N2H4.HSO4 amoni molipdat -(NHAM0A4.4H2O

2.4 PHirONG PHAP NGHlfiN ClTU

Trong dl tai nay chiing tdi thuc hien nghien ciiu dgc lap timg kim loai vdi cac yeu td nhu: pH, thdi gian, cac cha't dien ly anh hudng den kha nang hap giir cua axft humic Sau khi thuc hien cac nghien ciiu tinh de tim ra dilu kien tdi uu ciia phan ling chiing tdi nghien ciiu vdi hdn hgp cac kim loai va cho chay qua cdt cd chiia axft humic

d dang hat nhd de xem xet kha nang tach chiing ra khdi ngudn nudc Phuang phap nay dugc ggi la phuang phap nghien ciiu ddng

2.4.1 Phuang phap nghien cihi tinh

- can 0,100g axft humic cua hang Wako da dugc tinh che lai va ciia Viet Nam, nghiln nhd vdi kfch thudc < 0,45mm, cho vao binh tam giac 250ml

- Lay vao cdc loai 100ml: 40ml dung dich kim loai can nghien ciiu cd ndng do Img/ml, sau dd diing CH3C00Na, HCl, NaOH dilu chinh pH den cac muc khac nhau (kiem tra bang may do pH), rdi dinh miic 50ml va dd vao binh tam giac da cd 0,100g axft humic vira neu tren, lac diu trong hai tie'ng ddng hd Tien hanh lgc qua giay lgc bang xanh (I^l 1 Thu lay dung dich lgc

- Tien hanh phan tfch de tim ndng do kim loai cdn lai trong dung dich lgc va xac dinh chfnh xac lugng kim loai nghien cim bi hap giir bdi axft humic

15

Cac budc thf nghiem nghien ciiu anh hudng ciia thdi gian phan ung dugc tien hanh nhu sau:

- can 0,100g axft humic ciia hang Wako da dugc tinh che lai va cua Viet Nam, nghien nhd vdi kfch thudc < 0,45mm, cho vao binh tam giac 250ml

- La'y vao cdc loai 100ml: 50ml dung dich kim loai can nghien ciiu cd ndng do

1 mg/ml, sau dd diing CHgCOONa, HCl, NaOH dilu chinh pH den gia tri ma tai dd kha nang ha'p giii cua axft humic td't, sau dd dd vao binh tam giac da cd 0,100g axft humic viia neu tren va lac diu trong nhiing khoang thdi gian khac nhau tir 10 phiit de'n

6 gid Tien hanh lgc qua giay lgc bang xanh OH ngay sau khoang thdi gian da dinh

- Tien hanh phan tfch ddi tugng nghien cuu cdn lai trong dung dich va xac dinh chfnh xac lugng cac kim loai bi hap giu bdi axit humic

Khao sat anh hudng ciia mdt sd chat dien ly thudng cd trong mdi trudng nha't la trong nudc thai cua dung dich ma den phan ling dugc tien hanh nhu sau;

- Cho them vao dung dich nghien ciru nhirng chat dien ly nhu: (NH4)2S04, K2SO4, NaCI ,KC1

- Tien hanh phan tfch ndng do kim loai nghien ciiu cdn lai trong dung dich de tim ra lugng kim loai bi ha'p giii bdi axft humic

2.4.2 Phuong phap nghien cihi dong

Pha hdn hgp dung dich cac kim loai nghien ciru vdi ham lugng nhat dinh rdi dieu chinh pH thfch hgp, sau dd cho chay qua cot nhdi 4g axft humic (hat cd kfch thudc trong khoang tir 0,15mm de'n 0,45mm, dudng kfnh cdt 12mm, tdc do chay ban dau dieu chinh 3ml den 4ml/phiit, nhiet do phdng khoang 32''C Mdi 1ft dung dich hdn hgp dugc khuay them 0,5g axft humic bdt cd kfch thudc nhd hon 0,15mm

Cho dung dich hdn hgp chay qua cot axft humic Thu mdi phan doan 500ml de dem di phan tfch ndng do kim loai bang phuang phap hap thu nguyen tir

2.5 PHUONG PHAP PHAN TICH KIM LOAI

2.5.1 Phuang phdp xdc dinh Pb(II)

Dixng phuang phap chudn do Complexon vdi chi thi Xylen da cam

De chuan do true tie'p Pb^"^ trong dung dich axft cd the sir dung nhilu chat chi thi khac nhau nhung d day chiing tdi sir dung Xylen da cam( ky hieu XO) pha vdi KCI

- Thudc thir:

+ Dung dich EDTA 0,01N

+ Dung dich dem axetat pH = 5

+ Chi thi XO/KCl

Phuang phap xac dinh: Trung hoa sa bd dung dich bang NaOH de'n pH == 3 va them 3ml dung dem axetat, khi dd dung dich cd gia tri pH la 5 Them vao mdt ft chi thi va chuan do bang dung dich EDTA den chuyen mau tir tfm dd sang vang hoan toan Trong phuang phap chuan do nay ta can tranh ndng do dung dich dem axetat cao

vi khi dd diem tuong duang se khdng rd ret

chiing tdi nhan thay phuang phap nay cd do nhay va do chfnh xac cao Mat khac ham lugng kim loai dugc nghien ciiu d day la phii hgp vdi phuang phap chuan do complexon vi nhanh va re tiln Vdi ham lugng kim loai nhd phai diing phuang phap

do phd ha'p thu nguyen tir

2.5.2 Phuang phdp xdc dinh Cd(II)

Dixng phuang phap chuan do Complexon vdi chi thi Xylen da cam

Phep chuan do true tiep Cd""" vdi chi thi Xylen da cam tai pH = 5 se gap phai khd khan ve kha nang chuyen mau ciia chat chi thi tai diem tuang duang Do dd phai dung phep chuan do ngugc bang Zn^^

2.5.3 Phuang phdp xdc dinh Cu(II)

Phuang phdp xdc dinh dong bdng phep chudn do complexon

' Viec xac dinh nong do dong bang phuang phap chuan do complexon khdng ma'y khd khan cho dii la chuan do true tiep hay gian tiep Viec xac dinh ham lugng Cu^"^ bang phep chudn do complexon cd the thuc hien trong khoang pH rat rgng vdi cac chl thi khac nhau Trong luan van nay tdi tien hanh trong mdi trudng axft yeu tai

pH = 5 va sir dung chi thi xylen da cam Vdi ham lugng Cu^"" dugc nghien ciru trong cdng trinh nay thi viec ap dung phep chudn do complexon la rat td't

2.5.4 Phuang phdp xdc dinh Zn(II)

Dixng phuang phap chuan do complexon

2.5.5 Phuang phdp phdn tich As

- Phuang phap xac dinh asen d dang asenomolipdat xanh

- Nguyen tac: As(V) tuang tac vdi amonimolipdat tao thanh axft dj da asenomolipdic vang H3[As(Mo30io)4], rdi bi khir va chuyen thanh axft di da asenomolipdic xanh thudng dugc ggi la xanh asenomolipdic cd cudng do mau xanh ti

le vdi ndng do As Nghien ciiu ky su tao thanh xanh asenomolipdic da chi ra rang khi khir dang axft di da asenomolipdic vang xay ra hai qua trinh song song: tao xanh asenomolipdic don gian va pha huy mdt phan xanh asenomolipdic Cd the diing hydrazinsunfat, SnCl2, hydroquinon, axft asconic lam chat khir

Do do hap thu quang: Cue dai hap thu quang dang xanh asenomolipdic da khir phu thudc vao chat khir sir dung Do hap thu thudng dugc do d viing 700nm de'n 840nm He sd hap thu phan tir ciia xanh asenomolipdic d 840nm la 2,5.10'"^

- Thudc thir

-h Dung djch chuan asenat: can 0,132g AS2O3 rdi dem hoa tan trong 2 - 3ml kilm IN, chuyen vao dinh miic 100ml Axft hoa bang HCl tdi phan ling axit Them

0,5g kaliclorat rdi pha loang tdi vach dinh miic lac dl dugc dung dich cd ndng do Img As/ml

+ Amonimolipdat: Hoa tan Ig mudi amoni molipdat trong 100ml H2SO4 giii trong binh polietylen

+ Hydrazinsunfat: dung dich 0,15g/100ml

- Quy trinh phan tfch

La'y 20ml dung dich mau mdi trudng trung tfnh chiia tii 1 de'n 50|a.g As chuyen vao binh 30ml them vao 1ml amonimolipdat va 0,5ml dung dich hydrazinsunfat Dat binh len chau nudc sdi va giir 15 phiit ke tii liic nudc bat dau sdi trd lai Sau dd lay cac binh mSu ra, lam lanh dudi vdi nudc va chuyen dinh miic 25ml Tie'n hanh do quang d budc sdng 840nm, lap dudng chuan va tim nong do ciia As theo dudng chuan

La'y nhung lugng chfnh xac As khac nhau vao cac cdc dugc danh sd va tie'n hanh phan tfch bang phuang phap do quang xanh asenmolipdat tai budc sdng 840nm Ket qua thu dugc d hinh 2.1

dUdng hap thu quang

Hinh 2,1, Du&ng chudn do quang cua As

19

Thuc i6 asen ton tai d hai dang As(in) va As(V) Phuang phap xac dinh asen

bang do quang d dang asenomolipdat xanh chi thuc hien dugc cho As(V) Vi vay, khi xac dinh As(III) cfc phai dua As(III) len As(V).Chiing tdi chgn phuong phap dua As(III) len As(V) bang nudc brom nhu sau:

La'y vao cdc 50ml dung dich As(III) cd ndng do 1 mg/ml, sau dd them tirng gigt nudc brom lac tdi cd mau vang, de qua dem Dun sdi nhe khoang 15 phiit, lam ngudi, chuyen vao binh dinh miic 250ml Thu dugc dung dich As(V)

De chiing minh tfnh diing dan cua phuang phap tren tdi tien hanh pha dung dich chudn asen tir hoa phdm asenat-As(V) dugc dung dich As(V) 1 mg/ml Tie'n hanh len mau asenomolipdat xanh sau dd do quang ciia hai dung dich tren lai budc sdng 840nm ket qua dugc the hien d bang 2.1:

Bdng 2,1, Ket qud phdn tich so sanh giiia [Asilllj-^BrJ vd As(V) duac ten

mdu xanh asenmolipdat a budc song 840nm

As(V)

A S ( l l l ) JJ ^^^^ jy^ lgn ^^(V)

0,19 0,18

0,308 0,305

0,587 0,548

0,810 0,809

CHl/ONG 3 K £ T QUA v A THAO LUAN 3.1 Nghien cuu kha nang hap gift cua axit humic ddi vdi Pb^^

3.1.1 Nghien ci/u dnh hudtig cua pH den khd ndng hdp giu Pb^^

Axit humic la mdt axft yeu nen pH cd anh hudng manh den phan ling ciia axft humic ddi vdi Pb' De tim ra dilu kien pH tdi uu cho phan ling chiing tdi da khao sat vdi dieu kien pH tiif 1 ^ 6 Ket qua thu dugc nhu sau:

Bdng 3.1 dnh hudng cda pH den khd ndng hdp giU Pb bdi axit HAI

2

40 0,16 32,55 7,45 0,04

3

40 0,14 29,00 11,00 0,05

4

40 0,09 18,72 21,28 0,10

5

40 0,07 15,29 24,71 0,119

5,5

40 0,08 16,00 24,00 0,115

6

40 0,06 11,40 28,56 0,14

M : Ludng Pb'*

bi hap giur(mg)

pH

Hinh 3,1, dnh hudng cua pH den khd ndng hdp giit

Pb^^ bdi Axit HAI

Ke't qua nghien ciiu kha nang hap giii ciia Axft Humic ddi vdi Pb^'^cho thay phan ling rat tdt trong khoang pH tii 4,5 den 5,0 Tai khoang pH nay , vdi lOOmg axft humic

cd the ha'p giir tdi 24,71/40mg Pb'"" va hieu suat hap giir dat 61,8% ham lugng Pb^"" cd

21

trong dung dich Nhung d pH th^p thi anh hudng rat Idn va kha nang hap giii cua axft

humic vdi kim loai nay giam dk\,

^ Tuang tu thf nghiem nghien ciiu vdi HAI , chiing tdi da khao sat anh hudng ciia

pH den phan ling ciia HA2 vdi Pb^"" Ket qua thu dugc nhu sau:

Bang 3.2 anh hudng cua pH de'n phan ling cua axft humic HA2 vdi Pb 2+

2

40 0,16 32,55 7,45 0,04

3

40 0,13 27,80 12,20 0,06

4

40 0,09 19,50 20,50 0,10

5

40 0,08 15,70 24,30 0,12

5,5

40 0,08 15,60 24,40 0,12

6

40 0,06 12,50 27,50 0,13

Ket qua ciia bang 3.1 va bang 3.2 cho thay kha nang phan ling ciia Pb^^ vdi hai loai axft humic gSn nhu tuang duong nhau.Trong qua trinh nghien ciiu chiing tdi chi thuc hien dugc de'n pH = 4,5-5,5 Khi mdi trudng pH cao han dung dich Pb^"" se bi thuy phan

TCr ket qua tren ta cd the nhan dinh rang trong khoang pH tir 4,5 - 5,5 la thfch hgp cho kha nang phan ling ciia Pb^"*" vdi axit humic

3,1,2, Nghien citu dnh hudng cua th&i gian den khd ndng hdp giit

De nghien ciiu anh hudng cua thdi gian de'n kha nang hap giir ciia axft humic vdi chi, chiing tdi tien hanh khao sat thdi gian phan ling ciia axft humic vdi Pb^'^d pH = 4,5 tii 10 phiit de'n 360 phiit.Ket qua thu dugc nhu sau:

Bdng 3.3 Anh hudng cua th&i gian den khd ndng hdp giitPb^^ cua HAI dpH ^ 4,5

Thcri gian (phut)

20

50 0,12 25,07 24,93 0,12

30

50 0,12 24,86 25,14 0,12

60

50 0,10 21,24 28,76 0,14

90

50 0,11 21,76 28,24 0,14

120

50 0,10 21,13 28,87 0,14

180

50 0,10 20,82 29,18 0,14

240

50 0,10 19,68 30,32 0,15

360

50 0,09 19,48 30,52 0,15

23

400

sau:

.2+

Hinh 3,3, Anh hudng cua th&i gian den khd ndng hdp giit

boi Axit Humic HAI vdi Pb^^ tai pH^,5

Khao sat d ciing dilu kien nhu tren vdi axft humic HA2 dugc ket qua d bang

Bdng 3,4, dnh hudng cua th&i gian den khd ndng hdp giii: cua Axit HA2 v&i Pb'UaipH^4,5

Thai gian (phut)

20

50 0,12 24,35 25,65 0,12

30

50 0,11 21,96 28,04 0,14

60

50 0,10 20,82 29,18 0,14

90

50 0,10 21,65 28,35 0,14

120

50 0,11 21,86 28,14 0,14

180

50 0,10 20,51 29,49 0,14

240

50 0,10 19,89 30,11 0,15

360

50 0,05 10,67 39,33 0,19

Hinh 3,4, Anh hudng cua th&i gian den khd ndng hdp giU

cua axit humic HA2 v&i Pb^^ tai pH = 4,5

Tii nhirng ke't qua tai bang 3.3 va bang 3.4 ta nhan thay lugng Pb bi hap giii tang

nhanh trong khoang thdi gian phan ling ban dau Nhung tdi khi phan ung xay ra dugc han 2 gid thi ham lugng Pb^"" bi hap giir bdi ca hai loai axft humic tang khdng dang ke, phan ling dudng nhu da dat can bang

Nhu vay, sau qua trinh nghien ciiu kha nang hap giir ciia axft humic vdi Pb^"^, cd the ndi tai pH khoang tii 4,5 den 5,5 va thdi gian trong 2 gid la dilu kien thich hgp cho phan ling, dat hieu suat tdt nhat va tdi miic can bang

Mat khac, so sanh vl kha nang hap giii ciia hai loai axft humic Wako va Viet Nam vdi Pb^"" chiing tdi thay gan nhu tuang duang nhau

3.2 Nghien cuu kha nang hap giu cua axit humic vdi Cu"^

32.1 Nghien ciai dnh hirdng cua pH den khd ndng hdp giu

Tie'n hanh nghien ciru kha nang hap giir cua axit humic vdi Cu^"" tuang tu nhu vdi Pb^ Ket qua dugc chi ra trong bang dudi day

25

Bdng 3.5 dnh hudng cua pH den khd ndng

hdp gia cua axit HAI v&i Cu^^

2

40 0,285 18,24 21,76 0,34

3

40 0,2 12,8 27,2 0,425

4

40 0,187 11,94 28,06 0,439

5

40 0,155 9,92 30,08 0,47

6

40 0,08 5,12 34,88 0,545

Hinh 3.5 Anh huffng cua pH den khd ndng hdp giu

cua HAI v&i Cu^*

Ke't qua nghien ciiu anh hudng ciia pH den kha nang hap giir cua axft humic Viet Nam vdi Cu^"" dugc the hien d bang sau:

Bdng 3.6 Anh hudng cua pH den khd ndng

hdp gia cua Axit HA2 v&i Cu^^

2

40 0,274 17,54 22,46 0,351

3

40 0,236 15,10 24,90 0,389

4

40 0,189 12,11 27,89 0,436

5

40 0,164 10,50 29,50 0,461

6

40 0,10 6,43 33,57 0,525

Hinh 3.6 Anh hudng cua pH den khd ndng hdp giu

cdn axit HA 2 vdi Cu^^

11

Tii ke't qua nghien ciiu d bang 3.5, 3.6 va hinh 3.5, 3.6 cho thay d pH khoang ^

6 ham lugng Cu^"" bi ha'p giii ra't Idn, hieu sua't dat 87,2% ddi vdi Axft Humic Wako va 83,9% dd'i vdi Axft Humic Viet Nam Thuc te cho thay d khoang pH nay cd hien tugng mot ph& Cu^"^ bi thuy phan, hieu ling phu nay gay sai sd lam nhilu cac ket qua phan tfch, danh gia hieu sua't Qua ket qua d bang 3.5, kha nang phan ung giira Axft Humic Wako vdi Cu^"" trong khoang pH = 4,5 den 5,5 thi hieu suat hap giir dat 75,2% Nghien ciiu tha'y d khoang pH nay qua trinh phan ling diln ra rat thuan lgi, day la khoang pH thfch hgp nhat cho phan ung 6 vung pH nay, trong dilu kien thuc nghiem

da xet, lOOmg Axft Humic Wako cung nhu Axft Humic Viet Nam cd the hap giir dugc khoang 30mg Cu2-i- tiic la - 0,47 miii duong lugng gam ddng

3 2.2 Nghien ciifu anh hudng cua thdi gian den kha nang hap giii

Tie'n hanh khao sat su phu thugc cua kha nang hap giii Cu^"" bdi axit humic vao thdi gian phan ling thu dugc ket qua tren cac bang va hinh ve sau:

Bdng 3.7 Anh hudng th&i gian phdn ting den

khd ndng hdp giu cua axit HAI v&i Cu^^ tai pH = 5,0

Thcri gian (phiit)

40

50 0,143 9,15 40,85 0,64

60

50 0,136 8,67 41,33 0,65

120

50 0,116 7,39 42,61 0,67

180

50 0,116 7,40 42,60 0,67

240

50 0,111 7,07 42,93 0,67

360

50 0,119 7,64 42,36 0,66

Hinh 3.7 Anh hudng th&i gian phdn ling den khd ndng hdp giu

cua axit HAI vai Cu^^

Bdng 3,8, Anh hudng cua th&i gian den khd ndng hdp gia cua axit HA2 v&i Cu^^ tai pH = 5,0

Thcri gian (phiit)

40

50 0,143 9,15 40,85 0,638

60

50 0,136 8,67 41,33 0,646

120

50 0,120 7,71 42,29 0,661

180

50 0,110 7,07 42,93 0,671

240

50 0,111 7,07 42,93 0,671

360

50 0,119 7,64 42,36 0,662

29

Hinh 3.8 Anh hudng cda th&i gian den khd ndng

hnn oifr run A rit J-f A 2 \)/yi Cip-^

Qua hinh 3.7, 3.8 chiing ta thay ham lugng Cu^"" bi hap giii tang nhanh trong khoang thdi gian tir 20 de'n 60 phiit Nhung den khoang thdi gian tir 120 den 240 phut thi phan ling gan nhu dat gia tri can bang Qua bang ket qua 3.7, 3.8 ta cd the nhan thay sau 120 phiit thi kha nang hap giir ciia Axft Humic Viet Nam dat hieu suat la 84,6%, khi phan ling dugc 240 phut hieu suat ciing chi dat dugc 85,9% Nhu vay tii viec nghien ciiu tinh vl kha nang ha'p giir cua Axft Humic ddi vdi Cu^"" ta cd the nhan xet nhu sau:

Vl kha nang hap giii cua hai loai Axft Humic la tuang duang nhau, nhung Axft Humic cua Viet Nam hap giii cd phan kem han chiit ft

Thdi gian phan ling khoang 120 phiit la thfch hgp nhat mac du vdi thdi gian 240 phiit hieu suat hap giir cao hon chiit ft pH thfch hgp cho phan ling nay nam trong khoang 4,5 de'n 5,5

3.3 Ket qua nghien ciru kha nang hap giu cua Axit Humic vdi Zn^

3.3,1 Nghien cdu dnh hudng cua pH den khd ndng hdp gia