An Investigation of the Selective Adsorptions of Metals on Mesoporous NH 2 -MCM-41

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1 An Investigation of the Selective Adsorptions of Metals on Mesoporous NH 2 -MCM-4 Xinqing CHEN,3, Wai Kwong CHING, Koon Fung LAM, Wei WEI 3*, King Lun YEUNG,2* Department of Chemical and Biomolecular Engineering and 2 Division of Environment, the Hong Kong University of Science and Technology, Clear Water Bay, Kowloon, Hong Kong, P.R. China 3 CAS Key Laboratory of Low-carbon Conversion Science and Engineering, Shanghai Advanced Research Institute, Chinese Academy of Science, Shanghai 2020, P.R. China Figure S. TGA/DTA analyses of NH 2 -MCM-4 * Author to whom correspondence should be addressed King Lun YEUNG, Tel: ; Fax: ; kekyeung@ust.hk S

2 MCM-4 N-MCM-4 Figure S2. FT-IR analyses of MCM-4 and NH 2 -MCM-4 S2

3 Table S. The single component adsorption capacity (mmol/g) of Co 2+, Ni 2+, Cu 2+ and Zn 2+ on MCM-4 and NH 2 -MCM-4 respecitvely at room temperature. Adsorbents Co 2+ Ni 2+ Cu 2+ Zn 2+ MCM NH 2 -MCM S3

4 Table S2. Summary of the H and S values reported in the literature. Metals Adsorbents Temperature( o C) H(kJ/mol) S(kJ/mol.K) References Co 2+ Sepiolite Ni 2+ CNS chitosan Cu 2+ MWCWTs chitosan SBA Zn 2+ CNTs : Kara, M.; Yuzer, H.; Sabah, E.; Celik, M.S.; Adsorption of cobalt from aqueous solutions onto sepiolite. Water. Res. 2003, 37, : Kumar, P.S.; Ramalingam, S.; Kirupha. S.D.; Murugesan, A.; Vidhyadevi, T.; Sivanesan, S.; Adsorption behavior of nick(ii) onto cashew nut shell: Equilibrium, thermodynamics, kinetics, mechanism and process design. Chem. Eng. J. 20, 67, :Futalan, C.M.; Kan, C.C.; Dalida, M.L.; Hsien, K.J.; Pascua, C.; Wan, M.W.; Comparative and competitive adsorption of copper, lead, and nickel using chitosan immobilized on bentonite. Carbohydr. Polym. 20, 83, : Sheng, G.; Li, J.; Shao, D.; Hu, J.; Chen, C.; Chen, Y.; Wang, X.; Adsorption of copper (II) on multiwalled carbon nanotubes in the absence and presence of humic or fulvic acids. J. Hazard. Mater. 200, 78, : Da na, E.; Sayari, A.; Adsorption of copper on amine-functionalized SBA-5 prepared by co-condensation: Equilibrium properties. Chem. Eng. J. 20, 66, : Lu, C.; Chiu, H.; Liu, C.; Removal of Zinc (II) from aqueous solution by purified carbon nanotubes: Kinetics and Equilibrium Studies. Ind. Eng. Chem. Res. 2006, 45, S4

5 The method for calculating multicomponent Freundlich model at different ph: () The adsorption of H 3 O + on NH 2 -MCM-4 was determined from the Zeta potential plot with two simplifying assumptions. Assumption : The surface coverage of H 3 O + on NH 2 -MCM-4 (θ H3O+ ) is zero at the isoelectric point ph. Assumption 2: The surface coverage of H 3 O + on NH 2 -MCM-4 (θ H3O+ ) is ~ at the highest positive surface Zeta potential. Table S3 shows the calculations made from the Zeta-potential plot in Fig. 5a taken at room temperature. Figures S3a and S3b plot q H3O+ and θ H3O+ versus [H 3 O+] experimental data as well as model calculations from Freundlich adsorption model. It is clear that hydronium adsorption on the surface and protonation of the aminopropyls can be sufficiently described by a Freundlich equation. Table S3. H 3 O + adsorption on NH 2 -MCM-4 at T = 25 C ph [H 3 O + ] Zeta-potential Ө of [H 3 O + ] q H3O+ (ev) (mmol/g) a.2 b q H3O+ (mmol/g) θ H3O [H 3 O + ] [H 3 O + ] 0 S5

6 Figure S3 Plots of (a) adsorption isotherm (q e = 0.45C e.4 ) and (b) surface coverage versus [H 3 O + ] (θ e = 0.9C e.4 ) of hydronium ion on NH 2 -MCM-4. Please note that symbols are experimental data and lines are model calculations. (2) The single component adsorption of Cu 2+ on NH 2 -MCM-4 given Fig. 2c in the manuscript is replotted in Figure S4a and the corresponding surface coverage of Cu 2+, θ Cu2+ is plotted in Figure S4b. Please note that the adsorption of Cu 2+ on NH 2 -MCM-4 was carried out at ph 5 where H 3 O + adsorption and surface protonation can be considered negligible (i.e., θ H3O+ ~ 0). a.2 b q Cu2+ (mmol/g) θ Cu [Cu 2+ ] (mmol/g) [Cu 2+ ] (mmol/g) Figure S4 Plots of (a) adsorption isotherm (q e = 0.75C e 0.09 ) and (b) surface coverage versus [Cu 2+ ] (θ e = 0.95C e 0.09 ) of copper ion on NH 2 -MCM-4. Please note that symbols are experimental data and lines are model calculations. (3) This gave us the Freundlich adsorption isotherms of H 3 O + and Cu 2+ on NH 2 -MCM-4 at room temperature of 25 C as shown in the Equations S and S2, respectively. The adsorptions were expressed in term of θ H3O+ and θ Cu2+. The Freundlich adsorption isotherms of H 3 O +.4 : θ H3O+ = 0.9C e The Freundlich adsorption isotherms of Cu : θ Cu2+ = 0.95C e Eqn.S Eqn.S2 (4) Table S4 was prepared from the Cu 2+ adsorption data of Fig. 5b. It tabulates the ph, [H 3 O + ] and [Cu 2+ ], as well as the experimental q Cu2+. The competition coefficient (a ij ) between H 3 O + and Cu 2+ was calculated according to Sheindorf et S6

7 al. (980) in reference [26] of the manuscript using the single-component Freundlich adsorption equations Eqns. S and S2. The calculated a ij of 2.6 was obtained by least square fitting. surface coverage). Please note this is obtained in term of θ (i.e., Table S4. Cu 2+ adsorption versus ph at T = 25 C ph [H 3 O + ] [Cu 2+ ] qcu 2+ in experimental (mmol/g) (5) The following model calculations were made for the Cu 2+ adsorption from the Cu-Co-Ni ternary solutions at different phs (cf. Fig. 9a in the manuscript). The multicomponent Freundlich Equation (Eqn. S3) was used in the model calculations along with Eqns. S and S2 (i.e., single component Freundlich Equations for H 3 O + and Cu 2+ adsorptions), and the competition coefficient, a ij of 2.6 for H 3 O + and Cu 2+ using the experimental data from Fig. 5b. The same competition coefficients of Cu 2+ -Co 2+ and Cu 2+ -Ni 2+ from Table 5 are and 0.00, respectively. Please note a ii is.0 between Cu 2+ -Cu 2+. n N i q e, i = K ice, i aijce, j Eqn.S3 j= S7

8 The calculations are shown in Table S5 for Cu 2+ adsorption from the Cu-Co-Ni ternary solution at different solution phs. Figure S5 plots the experimental data and model calculations. The plot shows that there is good agreement between model and experiment. The process was used to calculate the relationship between metal ion adsorption and ph shown in the Figs. 7, 9 and 0b in the manuscript. Table S5. Cu 2+ adsorption from Cu-Co-Ni ternary solution at different phs ph [H 3 O + ] [Cu 2+ ] [Co 2+ ] [Ni 2+ ] q Cu2+ experimental (mmol/g) θ Cu2+ q Cu2+ Model Cal. (mmol/g) qcu 2+ (mmol/g) ph Figure S5 Plot of Cu 2+ adsorption on NH 2 -MCM-4 from Cu-Co-Ni ternary solutions at different phs. Please note that symbols are experimental data and lines are model calculations. S8

9 (6) It is important to note that this approach was possible as: (a) the surface of NH 2 -MCM-4 was relatively uniform, (b) the range of phs is narrow, (c) there is only a single dominant ion specie within the ph range. It would be more difficult to predict adsorption behavior on complex surfaces, as well as complex speciations and interactions at broader ph ranges. S9