Dissertation summary: Study on the synthesis and application of polymers containing suitable funtional groups for seperation some light rare earth elements

Objectives of the dissertation: Successfully synthesis polymers containing suitable funtional groups to seperate the light rare earth element (La, Nd, Pr, and Ce); evaluted the efficiency of polymers on seperating light rare earth element; evaluated the ability of polymers on separating each of the rare earth metal ions on the ion exchange column.

MINISTRY OF EDUCATION AND TRAINING VIETNAM ACADEMY OF SCIENCE AND TECHNOLOGY GRADUATE UNIVERSITY OF SCIENCE AND TECHNOLOGY - HOANG THI PHUONG STUDY ON THE SYNTHESIS AND APPLICATION OF POLYMER CONTAINING SUITABLE FUNTIONAL GROUPS FOR SEPERATION SOME LIGHT RARE EARTH ELEMENTS NGƯỜI H Scientific Fied: Organic Chemistry Classification Code: 9.44.01.14 S Nguyễn Văn Khôi DISSERTATION SUMMARY HA NOI - 2018 The dissertation was completed at: Institute of Chemistry Vietnam Academy of Science and Technology Scientific Supervisors: Prof Dr Nguyen Van Khoi Institute of Chemistry – Vietnam Academy of Science and Technology Dr Trinh Duc Cong Institute of Chemistry – Vietnam Academy of Science and Technology 1st Reviewer : ………………………………………………………… ………………………………………………………… 2nd Reviewer: ………………………………………………………… ………………………………………………………… 3rd Reviewer: ………………………………………………………… ………………………………………………………… The dissertation will be defended at Graduate University of Science and Technology, Vietnam Academy of Science and Technology, 18 Hoang Quoc Viet, Cau Giay District, Ha Noi City At ……hour…….date……….month…….2018 The dissertation can be found in National Library of Vietnam and the library of Graduate University of Science and Technology, Vietnam Academy of Science and Technology INTRODUCTION Background Rare earths are the special minerals, which are considered by many countries in the world and classified on material grade that can’t be replaced because they have many special properties Rare earth elements play a very important role in development of high-tech fields, such as: electricity, electronics, optics, lasers, superconductors materials and luminescent materials Thus, the title of dissertation was proposed: “Study on the synthesis and application of polymers containing suitable funtional groups for seperation some light rare earth elements”, to study on synthesize, characterization and application of polymers for sorption some light rare earth elements Objectives of the dissertation Successfully synthesis polymers containing suitable funtional groups to seperate the light rare earth element (La, Nd, Pr, and Ce); evaluted the efficiency of polymers on seperating light rare earth element; evaluated the ability of polymers on separating each of the rare earth metal ions on the ion exchange column Main contents of dissertation - Synthesis polymers containing suitable funtional group for the separation of the rare earth elements: + Synthesis poly(hydroxamic acid) from acrylamide (PHA-PAM) + Synthesis poly(hydroxamic acid) from acrylamide and vinyl sulfonate (PHA-VSA) - Studied on adsorption, desorption process; and evaluted the ability of two polymers on adsorpting some light rare earth metal ions (La3+, Ce4+, Pr3+ and Nd4+) - Studied and evaluted the capable of PHA resin on seperating some light rare earth elements (La3+, Ce4+, Pr3+ and Nd4+) Structure of the thesis The dissertation has 138 pages, including the literature review, experiment, results and discussions, conclusions, pubblication, with 45 images, 45 tables and 114 references B CONTENTS OF DISSERTATION CHAPTER I LITERATURE REVIEW An overview of domestic and foreign publications on rare earths, methods for seperate light rare earth metal ions; overview researchs on synthesis and application of polymers containing suitable funtional groups to separate rare earth metal ions From there, the research orientation of the dissertation were proposed CHAPTER II EXPERIMENTAL 2.1 Materials and equipments 2.1.1 Materials Acrylamide (AM), Sodium vinyl sulfonate (VSA), Ammonium persulfate; N, N’ - methylene bisacrylamide hydroxylamine hydrochloride (HA); Span 80, Paraffin oil, diesel oil, Dowex HCR-s resin, Amberlite IR 120 resin, standard solution: La(NO3)3, Ce(NO3)3, Pr(NO3)3, Nd(NO3)3; solution which contain light rare earth metal ions with content: La 3+ 36.76 wt%, Ce4+ 47.79 wt%, Pr3+ 4.41 wt%, Nd3+ 11.03 wt% was seperated and provided by Institute for Technology of Radioactive and Rare Elements, Vietnam Chemicals for analysis: distilled water, NaOH, NaHCO3,HCl, H2SO4, CH3OH,C2H5OH, C20H14O4, HNO3, C6H14, CHCl3, H2C2O4, CH3COOH, CH3COONa were used without purification 2.1.2 Equipments Equipments for suspension polymerization with three-liter of volume, ion exchange column, vacum dry cabinet, thermostatic tank, analytical balance, magnetic stirrer instrument, thermometer, flasks, the condenser system, triangular flasks, pipette, IR spectrometer, Perkin Elmmer emission spectrometer, thermogravimetric analyze instrument, FESEM scanning electron microscope, pH measuring equipment 2.2 Methods 2.2.1 Synthesis poly(hydroxamic acid) based on acrylamide Processes of synthesize cross-linking polyacrylamide (PAM gel) and synthesize poly(hydroxamic acid) (PHA) based on cross-linking polyacrylamide were presented in figure 2.4-2.6 - Diesel - Span 80 Continuous Phase V1 (ml) Invesstigated the factors: - AM Concentration - Temperature and time - Content of MBA - Content of ABS - Content of Span 80 - The stirrier speed - Monomer phase/oil phase ratio - Acrylamide: C% - MBA - APS Dispersed Phase V2 (ml) Reaction flask with liters of volume Filtered Feed speed: 10ml/min Washed by nhexane Cross-linking PAM Dried at 60oC long in hours Cross-linking PAM (granulate form with same size) Figure 2.4 Synthesis of PAM-gel PAM-gel (10 g PAM + 50 g H2O) Stirred: 100 rpm Time: 30 minutes Reaction flask with liters of volume Add NH2OH.HCl solution with concentration: 1-3.5 M, pH:10-14 Reation mixture: temperature T (oC), time t (min) Filtered Invesigated the factors - Temperature and time of reation - pH of medium -Concentration of NH2OH.HCl Washed by water to pH=7 Dried: 60oC, in hours Polyhydroxamic acid (granulate form had similar size and light yellow of colour) Figure 2.6 Sythesis of poly(hydroxamic axit) based on modification of PAM-gel 2.2.2 Synthesis poly(hydroxamic acid) from acrylamide and sodium vinyl sulfonate 2.2.2.1 Co-polymerization process of acrylamide and sodium vinyl sulfonate To investigated the coefficient of copolymerization process, controlled the conversion of reactions ≤ 10% (by reacting at very low concentration condition, experimented several times to conversion reached ≤ 10%) Synthesis samples of copolymer with difference of VSA/AM molar ratio: 10/90, 30/70, 50/50, 60/40, 70/30 and 90/10; other conditions of reaction didn’t change 2.2.2.2 Synthesis polymerization cross-linking P(AM-co-VSA) by suspension Process of synthesize cross-linking P(AM-co-VSA) was similar the suspension polymerization of AM; monomer were AM and VSA with VSA/AM weight ratio was 60/40 2.2.2.3 Modification of P(AM-co-VSA) to poly(hydroxamic acid) modified processes of copolymer of AM and VSA (P[AM-co-VSA]gel) were carried out similarly the modification of PAM-gel to PHA-PAM 2.2.3 Adsorption and de-adsorption the rare earth matal ions by PHA-PAM and PHA-VSA Adsorption: take 0.15 g PHA-PAM (or PHA-VSA) to reation flask containing 50 ml each of ion solution: La3+, Ce4+, Pr3+ and Nd3+ with research concentration, strirred at room temperature After reation time, measured the remaining concentration of each metal ion in solution using ICP-OES method * Investigated the factors that effect on adsorption process: pH, time, initiator concentration of metal ions * Adsorption isotherms: From the results obtained when investigated of factors on the adsorption process, Langmuir isotherm models was constructed 2.2.4 Studied on desorption and repeated use of poly(hydroxamic acid) resin Conducted six adsorption - desorption cycles using 0.15g of adsorbent material After each cycle, measured the percentage of metal adsorbed, the percentage of metal desorbed and the loss weight of absorbent 2.2.5 Absorbed the light rare earth ions on column by PHA-PAM Process of seperation light rare earth metal ions was showed in figure 2.8 Light rare earth metal ions composition: La3+, Nd3+, Pd3+ Ce4+ - Concentration: 500mg/l -pH=6; acetate buffer: 0.5 M Quantitative pump - : 130 ml/minute Ion exchange column - Dcolumn : 20mm - Lcolumn : 800mm - Lresin : 500mm Adsorbed in 180 minutes Washed with HCl 0.5M - Flow: 3-7 ml/minute - Vr/Vn: 3/1 – 18/1 Nd3+ rich fraction Pd3+ rich fraction Ce4+ rich fraction Adsorbed and desorped each fraction on ion exchange column Eluted by HCl: 0,6M Eluted by HCl: 0,1M Eluted by HCl: 0,2M Eluted by HCl: 0,4M Figure 2.8 Process of seperation light rare earth metal ions from rare earth metal solution by PHA resin CHAPTER III RESULTS AND DISCUSSION 3.1 Study on synthesis of poly(hydroxamic acid) based on acrylamide 3.1.1 Study on synthesis of cross-linked polyacrylamide (PAM-gel) In this study, the continuous phase used was diesel oil Factors influencing product properties were investigated such as temperature (7095oC) and time (60-240 min), monomer concentration (15-35%), APS concentration (0, 5-1.75), crosslinker concentration (7-11%), monomer / oil phase ratio (1 / 5-1 / 3), surfactant span 80 concentration (0.1-0, 35) and stirring speed (200-400 rpm) The results are presented in tables 3.13.6) Table 3.1 Effect of temperature and reaction time on characterization of PAM-gel Temp (oC) 70 80 90 95 Gel1 (%) 91,4 95 94,8 98,6 99,5 - Time (min) 180 240 60 90 60 60 D2TB (m) ~ 180  187 230 - Product characteristics Granular, block Granular, block Granular, block Discrete round granular Discrete round granular block Gel contents (%) Reaction efficiency reached the maximum value at 90oC, 60 minutes Thus, the condition of 90oC and 60 minutes was chosen as the reaction condition for the next study 35% 30% 25% 20% 15% 20 Time40 (min) 60 80 100 Figure 3.1 Effect of monomer concentration and reaction time on gel content of PAM-gel When the monomer concentration increases from 15% to 30%, the gel content increases and the reaction time decreases However, when monomer concentration is high (35% sample), the polymerization process is very fast, difficult to control the reaction process Therefore, 30% monomer was chose for optimal reaction temperature and time Gel content of products Average granular diameter of the product Table 3.2 Effect of initiator concentration on gel content and swelling capacity of PAM-gel KPS concentration, % 0,5 0,75 1,0 1,25 1,5 1,75 Gel content, % 93,2 96,8 99,5 98,4 98,0 97,3 Swelling capacity, g/g 3,2 3,9 4,7 4,2 3,8 3,6 Results showed that the optimum KPS concentration for PAM-gel synthesis was 1.0% Table 3.3 Effect of crosslinker concentration on swelling capacity and gel content of PAM-gel 10 11 MBA concentration (%) 6,2 5,8 5,5 4,7 4,1 Swelling capacity (g/g) 98 98 98,4 99,5 99,5 Gel content (%) Increasing of crosslinker concentration from to 11%, reduce the swelling capacity from 6,2 to 4,1 g/g Chosen MBA content is 10% for next study Table 3.4 Effect of ratio of monomer/oil phase on particle characteristics Ratio of Average diameter of Characteristics and monomer/oil granular` DTB(m) separability of granular phase 1/5  225 Round granules, evenly 1/4  230 Round granules, evenly 1/3 partially blocked At a monomer/oil phase ratio of 1/4, the granulation process is better, distributing the particle size more uniformly than the rest Table 3.5 Effect of suspension stabilizer on particle characteristics Span 80 Gel content Average content (%) ,% diameter of Characteristics and granular separability of particles DTB(m) 0,10 99,2 Unround granules, block 0,20 99,6 Unround granules, block 0,30 99,5  230 Round granules, evenly 0,35 98,5 Granular and partially emulsified Results in table 3.5 showed that, with 0,3% span 80, product are round granules, evenly Table 3.6 Effect of stirring speed on particle size distribution Stirring speed Particle size distribution (%) (rpm) < 100(m) 100÷500(m) >500(m) 200 7  55  38 300 4 92 4 400  38  57 5 With 300 rpm, the product is more uniform, with a particle size of 100-500m is 92% (Average diameter of granular is about 230 m) Thus, the optimal conditions for PAM-gel synthesis are: Reaction temperature 90oC for 60 minutes, 30% of monomer, 10% of crosslinker (in monomer), 1% of initiator, 0,3% of Span 80 at 300 rpm and ¼ of the phase ratio monomer/oil + Characteristic of PHA-gel: Particle size distribution with D ~230 µm, swelling capacity: 4.7 g/g and gel content of 99.5% 3.1.2 Sythesis of poly(hydroxamic axit) based on modification of PAM-gel To study the modification of PAM-gel into poly(hydroxamic acid) (PHA-PAM) by hydroxylamine, PAM-gel are 100-500 µm in size, humidity 99 8  50  42 300 >99 5 90 5 400 >99  45  50 5 The result was a optimum synthetic condition: reaction temperature o 90 C for 60 minutes, 30% of monomer, 8% of crosslinker (in monomer), 0,3% of Span 80 at 300 rpm 3.2.3 Sythesis of poly(hydroxamic axit) based on modification of P[AMco-VSA] In this study, Study on factors affacting the modification of P(AMco-VSA) to poly(hydroxamic acid) (PHA-VSA) were investered such as temperature (25-50oC), time (0-24 hours), pH (pH=10-14) and concentration of NH2OH.HCl (1.0-3.5M) The results are shown in figure 3.18 and tables 3.22-3.23 -CONHOH (mmol/g) 25 oC 30 oC 40 oC 50 oC 0 12 18 24 Time (min.) Figure 3.18 Effect of reaction temperature and time on funtional group content 13 Bảng 3.22 Effect of pH on funtional group content (mmol/g) pH 10 11 12 13 14 -SO3Na mmol/g 3,05 3,05 3,05 3,05 3,05 Bảng 3.23 Effect of NH2OH.HCl concentration on funtional group content - CONHOH mmol/g 1,2 1,53 4,24 7,15 8,135 NH2OH.HCl(M ) 1,0 2,0 3,0 3,3 3,5 -SO3Na mmol/g 3,05 3,05 3,05 3,05 - CONHOH mmol/g 3,74 4,98 8,135 8,01 3,05 7,89 Optimal condition for the modification of P(AM-co-VSA) to (PHAVSA): temperature 30oC for 18 hours, pH =14 with NH2OH.HCl 3.0M ➢ Product characteristics The results of IR spectral analysis, thermal TGA, surface morphology of PHA-PAM are shown in Table 3.24 and Figures 3.18-3.19 Table 3.24 Wavenumber of funtional group of P(AM-co-VSA) Wavenumber (cm-1) Bonds Groups 3425 N-H Primary (-NH2) 2933 C=N -CONHOH (enol form) 1666 C=O -CONH2 and -CONHOH 1182 S-O -SO31037 S=O -SO3- Figure 3.18 TGA thermal analysis diagram of PHA-VSA 14 Figure 3.1 SEM image of PHA-VSA Summany of item 3.2: - The optimal condition for the copolymerization of acrylamide and sodium vinyl sulfonate: reaction temperature 90oC for 60 minutes, 30% of monomer, 8% of crosslinker (in monomer), 1% of initiator, 0,3% of Span 80 at 300 rpm and ¼ of the phase ratio monomer/oil +The optimal condition for the modification of P[AM-co-VSA] into PHA-VSA: reaction temperature 30oC for 18 hours, concentration of NH2OH.HCl 3.0M, pH14 at 100 rpm + Characteristic of PHA-PAM: Particle size distribution with D ~232 µm, swelling capacity: 9.67 g/g, -CONHOH content: 8.315 mmol/g, SO3Na content: 3,05 mmol/g 3.3 Adsorption and desorption of rare earth ions by PHA-PAM and PHAVSA 3.3.1 Adsorption of rare earth ions by PHA-PAM and PHA-VSA In this study, the important factor that influence the adsorption processes include pH, time and initial metal concentration The results are shown in figures 3.20-3.25 120 120 90 90 Q (mg/g) 150 Q (mg/g) 150 La(III) Ce(IV) Pr(III) Nd(III) 60 30 pH 30 0 La(III) Ce(IV) Pr(III) Nd(III) 60 8 pH Figure 3.20 Effect of pH on the adsorption process of PHA-PAM Figure 3.21 Effect of pH on the adsorption process of PHA-VSA 15 150 120 120 90 La(III) Ce(IV) Pr(III) Nd(III) 60 Q (mg/g) Q (mg/g) 150 30 90 60 30 0 60 120 Time (min) 180 240 Figure 3.22 Effect of time on the adsorption process of PHA-PAM 150 150 120 120 90 90 La(III) Ce(IV) Pr(III) Nd(III) 60 30 120 180 Time (min) 240 300 La(III) Ce(IV) Pr(III) Nd(III) 60 30 0 60 Figure 3.23 Effect of time on the adsorption process of PHA-VSA Q (mg/g) Q (mg/g) La(III) Ce(IV) Pr(III) Nd(III) 100 200 300 400 500 600 Initial metal concentration (mg/l) Figure 3.24 Effect of initial metal concentration on the adsorption process of PHA-PAM 100 200 300 400 500 600 Initial metal concentration (mg/l) Figure 3.25 Effect of initial metal concentration on the adsorption process of PHA-VSA The results shown that, optimal condition for adsorption process: pH=6, initial metal concentration is 500 mg/L metal ion, in 180 minutes ✓ Isothermal absorption Isothermal absorption Langmuir equations were built for La3+, Ce4+, Pr3+ Nd3+, are shown in figure 3.29 Table 3.25 Parameters of adsorption Langmuir process La3+ Pr3+ Ce4+ R2(Langmuir) 0,97735 0,97746 0,9686 RL 0,112 0,175 0,133 PHAqmax (mg/g) 234,19 209,64 196,08 PAM qe 143,5 131,42 129,33 b bond energy constant 0,0159 0,0094 0,013 0,9557 0,9908 0,9901 PHA- R (Langmuir) VSA RL 0,123 0,126 0,204 16 Nd3+ 0,9075 0,190 212,77 136,67 0,0085 0,9390 0,235 qmax (mg/g) 192,31 178,57 153,85 178,57 qe 129,6 125,54 115,33 121,07 b bond energy constant 0,0142 0,0078 0,0138 0,0065 The values of RL in range of 0,112-0,235, less than 1, the Langmuir isothermal model is suitable for adsorption La3+, Ce4+, Pr3+ Nd3+ on PHA-PAM, PHA-VSA Besider, the maximum adsorption capacity of PHA-PAM was higher than PHA-VSA Therefore, PHA-PAM is chosen for next study 3.3.2 Desorption rare earth metal ions by PHA-PAM 150 150 120 Ce4+ content (mg/g) La3+ content (mg/g) 3.3.2.1 Effect of eluted solution In this study, the desorption of rare earth metal ions (La3+, Ce4+, Pr3+ and Nd3+) form the PHA-PAM resin were investigated with 0.5M HCl, 0.5M acitic acid and 0.5M oxalic acid aqueous solutions The results of desorption efficiency for rare earth metal ions in three eluted solution are shown in Figures 3.30-3.33 HCl 0.5M Axetic 0.5M Oxalic o.5M 90 60 30 0 60 120 180 240 300 HCl 0.5M Axetic 0.5M Oxalic 0.5M 120 90 60 30 0 360 60 120 180 240 300 360 Time (min) Time (min) Figure 3.31 Effect of eluted solution on desorption of ion Ce4+ 150 150 HCl 0.5M Axetic 0.5M Oxalic 0.5M 120 90 60 30 Nd3+ content (mg/g) Pr3+ content (mg/g) Figure 3.30 Effect of eluted solution on desorption of ion La3+ HCl 0.5M Axetic 0.5M Oxalic 0.5M 120 90 60 30 0 60 120 180 240 300 360 Time (time) Figure 3.32 Effect of eluted solution on desorption of ion Pr3+ 60 120 180 240 Time (min) 300 360 Figure 3.33 Effect of eluted solution on desorption of ion Nd Nd3+ According to the results mentioned above, HCl solution was an 17 effective and suitable desorption agent for recovering rare earth metal ions from PHA-PAM resin 3.3.2.2 Effect of elution HCl concentration Studying HCl concentration in range of 0,1-0,8M The results are shown in figure 3.34 1000 La(III) 800 Pr(III) Ce(IV) 600 Kd Nd(III) 400 200 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 HCl content (M) Figure 3.34 Effect of elution concentration on separability of ions from PHA-PAM -Ion Nd3+ : good separability at ~ 0,1M HCl - Ion Pr3+ : good separability at ~ 0,2M HCl - Ion Ce4+: good separability at ~ 0,4M HCl - Ion La3+ : good separability at ~ 0,6M HCl 3.3.3 Desorption and repeated use The plastic used in this study was PHA-PAM After desorption, PHAPAM resin was regenerated by washing with distilled water to neutral pH, dried in vacuum at 60 ° C to constant volume and continued for six adsroption – desorption cycles each metal ion The results showed that the adsorption capacity of PHA-PAM decreased slightly after six adsorption – desorption cycles, but adsorption capacity remained high Adsorption capacity of PHA-PAM after six adsorption – desorption cycles with La3 +, Ce4 +, Pr3 + and Nd3 + ions were 95.2, 95.7, 95.6, and 94.2 respectively 3.3.4 Comparision of Dowex, Amberlit and PHA-PAM adsorbents The process of adsorption of rare earth metal ions on Dowex, Amberlite and PHA-PAM resins and the desorption are carried out under the same conditions The results are shown in Table 3.30 18 Bảng Adsorption capicity and desorption percentage of Dowex, Amberlit and PHA-PAM with La3+, Ce3+, Pr3+, Nd3+ Resin Adsorption capacity, desorption percentage Dowex PHAPAM Nhựa Amberlit Rare earths metal ions Adsorption capacity, q (mg/g) Desorption percentage (%) La3+ 122,8 76,14 Ce3+ 108,7 73,38 Adsorption capacity, q (mg/g) 143,5 129,33 Desorption percentage (%) Adsorption capacity, q (mg/g) Desorption percentage (%) 95,2 120,2 75,87 95,7 109,8 75,04 Pr3+ 110,4 69,42 Nd3+ 111,6 71,44 136,6 131,42 95,6 94,2 111,4 108,7 65,68 70,15 The results show that adsorption capacity and desorption percentage of Dowex and Amberlite are lower than PHA-PAM Summany of item 3.3 - The optimal conditions for the adsorption of rare earth metal ions to PHA-PAM and PHA-VSA including: initial metal concentration of 500 mg/l for 180 minutes at pH Under all conditions, the adsorption capacity of PHA-PAM for rare metal ions (La3+, Ce3+, Pr3+, Nd3+) were higher than PHA-VSA - Elution conditions: the adsorbed Nd3+, Pr3+, Ce4+ and La3+ on PHA-PAM could be desorbed in 0.1M, 0.2M, 0.4M and 0.6M HCl, respectively - Comparison of rare earth metal ions adsorption of Dowex, Amberlite and PHA-PAM resins, the results show that the adsorption capacity and desorption percentage of PHA-PAM resin are higher than the other two resins 3.4 Separating individual ions in lighter rare earth solution by PHAPAM on ion exchange column In this study, the lighter rare earth solution was seperated from rare earth Dong Pao (seperated and supplied by Institute for Technology of Radioactive and Rare Elements) The components of lighter rare earth solution shown in table 3.29 Table 3.29 Chemical components of lighter rare earth solution Item Ion components Content (mg/l) % La(III) 185,4 36,76 Ce(IV) 238,9 47,79 19 Pr(III) Nd(III) Đất nhẹ (g/l) 23,9 51,8 500mg/l 4,41 11,03 3.4.1 Studying of desorption process 3.4.1.1 Effect of volumn and rate of eluted solution The elute solution is 0.5M HCl with Vr/Vn ratios from 3:1 to 18:1 The results are shown in table 3.30 Table 3.30 Effect of volumn and rate of eluted solution Total amount of rare earth ions is eluted (%) Vr/Vn (ml) v1 = ml/min v2 = 5ml/min v3 = 7ml/min 3:1 34,84 59,94 45,24 6:1 71,85 85,21 78,38 9:1 90,02 91,05 90,87 12:1 91,52 92,91 92,85 15:1 93,54 98,20 97,19 18:1 97,04 98,34 98,22 The results show that in the Vr/Vn ratios and flow rates, only Vr/Vn = 15:1 and and flow rate of ml/min for the elution efficiency is the best 3.4.2 Seperated process for individual La(III), Ce(IV), Pr(III) and Nd(III) ions from the respective rich segment 3.4.2.1 Seperated process of La3+ ion from La-rich segment 100 La (%) 90 83.3 Ce (%) 80 Pr (%) 70 60 Nd (%) 50 40 30 12.15 20 10 92.8 20.68 23.99 Ion concentration (%) Ion concentration (%) Seperated process of La3+ from La-rich segment are shown in figure 3.36-3.37 Segment Hình 3.36 The result of secondary adsorption-desorption from primary La-rich segment 100 92.8 90 80 70 60 50 40 30 20 10 96.63 La (%) Ce (%) Pr (%) Nd (%) 27.14 31.28 32.97 Segment Hình 3.37 The result of tertiary adsorption-desorption from secondary La-rich segment 20 La3+ ion content reaches 96,63% in 1721-2400 segment 3.4.3.2 Seperated process of Ce4+ion from Ce-rich segment Seperated process of Ce4+ion from Ce-rich segment are shown in figure 3.38-3.39 90 80 70 60 100 90.56 La (%) 78.03 Ce (%) Pr (%) Nd (%) 50 40 26.18 23.47 30 16.51 20 10 Ion concentration(%) Ion concentration(%) 100 90 80 70 95.94 90.56 La (%) Ce (%) Pr (%) Nd (%) 60 50 40 32.08 29.63 30 22.68 20 10 Segment Segment Hình 3.38 The result of secondary adsorption-desorption from primary Ce-rich segment Hình 3.39 The result of tertiary adsorption-desorption from secondary Ce-rich segment Ce4+ ion content reaches 95,94% in 1041-1720 segment 100 90 80 70 60 50 40 30 20 10 82.56 68.27 32.89 La (%) Ce (%) Pr (%) Nd (%) 27.94 18.49 Element contetn(%) Element content(%) 3.4.3.3 Pr3+ seperated process from Pr-rich segment Seperated process of Pr3+ from Pr-rich segment are shown in figure 3.40-3.42 Segment Figure 3.40 The result of secondary adsorption-desorption from primary Pr-rich segment 100 90 80 70 60 50 40 30 20 10 La (%) Ce (%) Pr (%) Nd (%) 91.87 82.56 36.57 31.68 23.25 Segment Figure 3.41 The result of tertiary adsorption-desorption from secondary Pr-rich segment 21 La (%) Element content(%) 120 100 Ce (%) 95.87 91.87 Pr (%) Nd (%) 80 60 40.25 37.72 40 32.94 20 Segment Figure 3.42 The result of quaternary adsorption-desorption from tertiary Pr-rich segment Pr3+ ion content reaches 95,87% in 481-1040 segment 3.4.3.4 Nd3+ seperated process from Nd-rich segment 90 80 70 60 50 40 30 20 10 84.99 La (%) Ce (%) Pr (%) Nd (%) 76.64 42.98 35.66 25.92 Segment 100 90 80 70 60 50 40 30 20 10 91.52 La (%) Ce (%) Pr (%) Nd (%) 84.99 Ion concentration (%) Ion concentration (%) Seperated process of Nd3+ from Nd-rich segment are shown in figure 3.43-3.45 46.89 36.84 30.69 Segment Hình 3.43 The result of secondary adsorption-desorption from primary Nd-rich segment Hình 3.44 The result of tertiary adsorption-desorption from secondary Nd-rich segment 22 100 91.52 95.42 La (%) Element content (%) 90 Ce (%) 80 70 60 46.89 50 40 32.45 30.09 30 20 10 Ban đầu 40-480 481-1040 1041-1720 1721-2400 Segment Figure 3.45 The result of quaternary adsorption-desorption from tertiary Nd-rich segment Nd3+ ion content reaches 95,42% in 40-480 segment Summany of item 3.4: Rare earth metal ions (La3+, Ce4+, Pr3+ Nd3+) were seperated sucessfully on ion exchanged column with PHA-PAM resin The adsorption and desorption by HCl with diferent concentration were carried out through segments Recovery efficiency is greater than 95%, purity of element: La-96,63 %, Ce-95,99 %, Pr-95,87 % and Nd95,42 % CONCLUSION Poly(hydroxamic acide) based on acrylamide was synthesized sucessfully through stages: - Polyacrylamide was synthesized by suspension polymerization method The product are round even granules, diameter ~230 µm, gel content 99,5 % and swelling capacity 4,7 g/g - Polyacrylamide was modified to poly(hydroxamic acid) by hydroxylamine hydrocloride at pH=14, temp 30 oC in 24 h, 3.3M NH2OH.HCl PHA obtained resin is round even granular form, average diameter ~230 µm, -CONHOH 11.34 mmol/g, -CONH2 2.73 mmol/g, COOH 1.68 mmol/g, swelling capacity 5.23 g/g Poly(hydroxamic acid) based on acrylamide sodium vinylsulfonate (PHA-VSA) was synthesized sucessfully through stages: - Copolymerization of AM and VSA by reverse suspension polymerization in oil Obtained copolymer is round even granular form, 23 average diameter ~232 µm, gel content 99 % and swelling capacity 9,5 g/g - Copolymer P[AM-co-VSA] was modified by hydroxylamine hydroclorit at pH=14, temp 30 oC in 18 h, NH2OH.HCl 3,0 M Obtained PHA-VSA polymer is round even granular form, average diameter ~232 µm, -CONHOH 8,13 mmol/g, -SO3Na: 3,05 mmol/g, swelling capacity 9,65 Both of polymer PHA-PAM and PHA-VSA have light rare earth ions adsorption capacity Adsorption content of La3+, Ce4+, Pr3+ and Nd3+ in PHA-VSA in range of 115-130 mg/g, in PHA-PAM in range of 130-143 mg/g PHA-PAM adsorption capacity is better than PHA-VSA Light rare earth ions (La3+, Ce4+, Pr3+ Nd3+) were seperated sucessfully in PHA-PAM ion exchanged column Adsorption- desorption process by HCl with difference content through segment Recovery efficiency is greater than 95%, purity of element: La-96,63 %, Ce-95,99 %, Pr-95,87 % and Nd-95,42 % Research has successfully made and used hydroxamic acid functional polymers to separate some of the light rare elements that have opened up a new pathway to contribute to the rare soil processing sector in Vietnam The results related to the thesis have been published on articles of national scientific journals and international conferences THE CONTRIBUTES OF DISERTATION This dissertation studied the conditions to synthesis two resins for ion exchanging: synthesized poly(hydroxamic acid) based on acrylamide (PHA-PAM), synthesize poly(hydroxamic acid) based on acrylamide and sodium sulfonate (PHA-VSA) Two resins had high ability on sorption and purification of some light rare earth elements (La3+, Ce4+, Pr3+ and Nd3+) The PHA-PAM ion exchange resin was used to seperate and purify some light rare earth ions contained in Vietnam's Dong Pao rare earth ore Experiment results showed that PHA-PAM had ability in individually seperation of light rare earth ions and provied the purify of ions over 95% It revealed that PHA-PAM which synthesized as presented in dissertation can used in seperation and purification of light 24 rare earth ions via ion exchange chromatography method PUBLICATIONS Trinh Duc Cong, Nguyen Thanh Tung, Tran Vu Thang, Nguyen Thi Thuc, Hoang Thi Phuong - Adsorption La(III) and Nd(III) ions by poly(hydroxamic acid) based on acrylamide and vinyl sulfonic acid, Vietnam Fournal of Chemistry, 52(6A), 122-125, 2014 Hoang Thi Phuong, Nguyen Van Khoi, Nguyen Thi Thuc, Luu Thi Xuyen, Trinh Duc Cong - Adsorption Ce(III) and Pr(III) ions by poly(hydroxamic acid) based on acrylamide and vinyl sulfonic acid, Vietnam Fournal of Chemistry, 53(6e1,2), 10-13, 2015 Trinh Duc Cong, Hoang Thi Phuong, Nguyen Thi Thuc, Nguyen Van Manh, Nguyen Van Khoi -Synthesis poly(hydroxamic acid) by modification of polyacrylamide hydrogels with hydroxylamine hydrochloride and application for adsorption of La(III), Pr(III) ions, Vietnam Fournal of Chemistry, 53(5), 663-668, 2015 Trinh Duc Cong, Nguyen Van Khoi, Nguyen Thi Thuc, Pham Thi Thu Ha, Tran Vu Thang, Hoang Thi Phuong - Study on synthesis of poly(hydroxamic acid) based on acrylamide and vinyl sunfonic acid, International Workshop on Advanced Materials Science and Nanotechnology (Ha Long: 11-2014) , P.398, 2014 Hoang Thi Phuong, Nguyen Thi Thuc, Tran Vu Thang, Trinh Duc Cong – Synthesis of poly(acrylamide – co – sodium vinyl sulfonate) by inverse suspension method, Vietnam Fournal of Chemistry, 54(6e2), 147-150, 2016 Hoang Thi Phuong, Nguyen Van Khoi, Nguyen Thi Thuc, Tran Vu Thang, Trinh Duc Cong – Study on influence factors on inverse suspension polymerization of polyacrylamide hydrogel and characteristics Vietnam Fournal of Chemistry, 55(5E34), 359-363, 2017 25 ... Thus, the title of dissertation was proposed: ? ?Study on the synthesis and application of polymers containing suitable funtional groups for seperation some light rare earth elements? ??, to study on. .. each of the rare earth metal ions on the ion exchange column Main contents of dissertation - Synthesis polymers containing suitable funtional group for the separation of the rare earth elements: ... synthesize, characterization and application of polymers for sorption some light rare earth elements Objectives of the dissertation Successfully synthesis polymers containing suitable funtional