Supporting Information For Removal of Antimonite (Sb(III)) and Antimonate (Sb(V)) from Aqueous Solution Using Carbon Nanofibers that Are Decorated with Zirconium Oxide (ZrO 2 ) Jinming Luo,, Xubiao Luo, John Crittenden,*, Jiuhui Qu,*, Yaohui Bai, Yue Peng, # and Junhua Li # Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, People s Republic of China Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, PR China Brook Byers Institute for Sustainable Systems and School of Civil and Environmental Engineering, Georgia Institute of Technology, 828 West Peachtree Street, Atlanta, Georgia, 30332, United States # State Key Joint Laboratory of Environment Simulation and Pollution Control, School of Environment, Tsinghua University, Beijing, 100084, China *Corresponding author John Crittenden (E-mail: john.crittenden@ce.gatech.edu) Jiuhui Qu (E-mail: jhqu@rcees.ac.cn) 1
Section 1. The mathematical calculation of the adsorption capacity happened on unit area of t-zro 2 and m-zro 2 (111) plane. Section 2. The mathematical derivation process of the mass flow rate equation Figure S1. EDS spectra for ZCN. Figure S2. (a) SEM image and (b-d) SEM-mapping images of the ZCN. Figure S3. Adsorption isotherm for Sb(III) and Sb(V) adsorption on particles ZrO 2. Initial Sb(III) and Sb(V) concentration was 20-200 mg/l; adsorbent dose was 1g/L; the solution volume was 20 ml; and ph was 7.0 ± 0.2 and the temperature was 25 o C ± 0.2. Figure S4. D-R isotherm plots obtained for the adsorption of (a) Sb(III) and (b) Sb(V) on ZCN. Figure S5. Plot of ln k L versus 1/T obtained for the adsorption of (a) Sb(III) and (b) Sb(V) on ZCN. Figure S6. The performance ZCN on Sb removal in (a) tap water and (b) deionized water. The initial Sb(III) and Sb(V) concentration was 200 µg/l; adsorbent dose was 2 g/l; the solution volume was 50 ml; the ph was 7.0 ± 0.2 and the temperature was 25 o C ± 0.2. Figure S7. The net charge of the optimized (a) t-zro 2 (111) plane and (b) m-zro 2 (111) plane slab models with Sb(III) adsorption, alone with the optimized (c) t-zro 2 (111) plane and (d) m-zro 2 (111) plane slab models with Sb(V) adsorption. Antimony atoms are purple, oxygen atoms are red, zirconium atoms are light blue, and hydrogen atoms are white. Table S1. Langmuir and Freundlich parameters for Sb(III) and Sb(V) adsorption on the ZrO 2 particles Table S2. The performance comparison between the ZCN and various adsorbents for Sb removal from water Table S3. D-R model parameters calculated for both Sb(III) and Sb(V) adsorption on ZCN Table S4. Thermodynamic parameters calculated for both Sb(III) and Sb(V) adsorption on ZCN at different temperatures Table S5. The details of XPS fitting results Number of pages: 19 Number of sections: 2 Number of figures: 7 Number of tables: 5 2
Section 1. The mathematical calculation of the adsorption capacity happened on unit area of t-zro 2 and m- ZrO 2 (111) plane is expressed by Eq. (1): Pt P q x P P S m max + y= (1) total total BET P t is the intensity of t-zro 2 ; P m is the intensity of m-zro 2, P total is the sum intensity of t-zro 2 and m-zro 2, q max (mg/g) is the maximum adsorption capacity simulated by Langmuir model, S BET (m 2 /g) is the BET value from the experiment data, x (mg/m 2 ) is Sb adsorbed on t-zro 2, and y (mg/m 2 ) is Sb adsorbed on m-zro 2. We can calculate the x and y by use the ZCN and ZrO 2 particles data. 3
Section 2. The mathematical derivation process of the mass flow rate equation: Mathematically, the mass flow rate of Sb ion is given by the expression of Eq (2): d C = k f a ( C C s) (2) dt where k f is the mass transfer coefficient (cm/s), a is the specific area available for mass transfer per unit volume of the contactor (1.07 10 5 m 2 /m 3 ), C is the concentration of Sb ion in bulk solution (mol/l), C s is the concentration of Sb ion at interface (mol/l). Assume the adsorption fit linear isotherm Eq (3): q kc q= m s (3) 1 + kcs where k is the adsorption equilibrium coefficient (L/mmol) and q is the adsorption capacity (mg/g), which can be calculated by the following Eq (4): V q= ( C0 Cs ) (4) M where V is the contactor volume (0.2 L), m is the mass of ZCN (0.2 g), and C 0 is the initial concentration of Sb ion in bulk solution (20 mg/l). Combining Eqs. (2-4) yields Eq (5): dc 1 qmm 1 4C q m 1 = k f a [ C ( ( C + ) + + C )] (5) dt 2 V k k V k 2 0 m 0 0 l l l To describe the sorption data with the model, we derived the concentration of Sb ion in bulk solution (C) as a function of time (t) with Eq. (6): C bexp[ ht] + C b (6) = 0 In Eq (5), h and b are the fitting parameters. h= k a and f 4
1 q m 1 4C q m 1 b= C ( ( C + ) + + C ). Thus Eq (6) is used to fit the m 2 0 m 0 0 0 2 V kl kl V kl experimental results with h and b as fitting parameters. 5
Figure S1. EDS spectra for ZCN. 6
Figure S2. (a) SEM image and (b-d) SEM-mapping images of the ZCN. 7
Figure S3. Adsorption isotherm for Sb(III) and Sb(V) adsorption on particles ZrO 2. Initial Sb(III) and Sb(V) concentration was 20-200 mg/l; adsorbent dose was 1g/L; the solution volume was 20 ml; and ph was 7.0 ± 0.2 and the temperature was 25 o C. 8
Figure S4. D-R isotherm plots obtained for the adsorption of (a) Sb(III) and (b) Sb(V) on ZCN. 9
Figure S5. Plot of lnk versus 1/T obtained for the adsorption of (a) Sb(III) and (b) Sb(V) on ZCN. 10
Figure S6. The performance ZCN on Sb removal in (a) tap water and (b) deionized water. The initial Sb(III) and Sb(V) concentration was 200 µg/l; adsorbent dose was 2 g/l; the solution volume was 50 ml; the ph was 7.0 ± 0.2 and the temperature was 25 o C ± 0.2. 11
Figure S7. The net charge of the optimized (a) t-zro 2 (111) plane and (b) m-zro 2 (111) plane slab models with Sb(III) adsorption, alone with the optimized (c) t-zro 2 (111) plane and (d) m-zro 2 (111) plane slab models with Sb(V) adsorption. Antimony atoms are purple, oxygen atoms are red, zirconium atoms are light blue, and hydrogen atoms are white. 12
Table S1. Langmuir and Freundlich parameters for Sb(III) and Sb(V) adsorption on the ZrO 2 particles Temperature ( ) Equations Langmuir model Freundlich model Parameters q m (mg/g) k L (L/mg) R 2 n k F (mg 1-(1/n) L 1/n g -1 ) R 2 25 Sb(III) 23.4536 0.0838 0.9523 5.5043 8.7277 0.8402 Sb(V) 22.64 0.0051 0.9752 1.4797 0.3367 0.9743 13
Table S2. The performance comparison between the ZCN and various adsorbents for Sb removal from water Adsorbents Concentration range (mg/l) ph Dose (g/l) Adsorption capacity(mg/g) Reference Sb(III) Sb(V) Present study 10-500 (initial concentration) 7.0 ± 0.2 1 70.83 57.17 - α-feooh - 2.0-12.0 25-48.7 1 Kaolinite 1 (initial concentration) 6.0 25-12 2 Bentonite 0.05-4 (initial concentration) 6.0 25 0.500 0.556 3 Diatomite 10-400 (initial concentration) 6.0 4 35.2-4 Activated alumina 5 75 (initial concentration) 2.0-11.0 1-38 5 Nanoscale zero-valent iron 0 20 (initial concentration) 4-10 2 6.99 1.65 6 Iron-zirconium bimetal oxide 0-25 7.0 0.2-51 7 Hematite coated magnetic 8 1-20 4.1 0.1 36.7 - nanoparticle Synthetic manganite 0.5-98 3.0 0.6-95 9 14
Table S3. D-R model parameters calculated for both Sb(III) and Sb(V) adsorption on ZCN Sb(III) Sb(V) q m (mol/g) 1.8 10-3 q m (mol/g) 9.1 10-4 β (mol 2 /J 2 ) 6.37 10-9 β (mol 2 /J 2 ) 4.84 10-9 E (kj/mol) 8.9 E (kj/mol) 10.2 R 2 0.9989 R 2 0.9954 15
Table S4. Thermodynamic parameters calculated for both Sb(III) and Sb(V) adsorption on ZCN at different temperatures Sb(III) Sb(V) T (K) lnk G (kj/mol) T (K) lnk G (kj/mol) 298 5.06 12.56 298 4.88 12.12 308 4.87 12.40 308 4.71 12.05 318 4.7 12.28 318 4.51 11.90 0 H (kj/mol) 14.98 0 S ( J/mol K) 8.19 0 H (kj/mol) 14.56 0 S (J/mol K) 8.11 16
Table S5. The details of XPS fitting results Sample Composition (%) Binding energy (ev) O ad /O latt O latt O ad O H2O Sb 3d 3/2 Sb 3d 5/2 Zr-O Untreated adsorbents 14.8 530.1 531.4 532.2 - - 182.6/185.0 Sb(III) 16.0 529.9 531.5 532.5 530.7 539.8 182.5/184.8 Sb(V) 16.9 529.9 531.4 532.4 530.7 540.0 182.4/184.7 17
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