Surface properties and chemical constitution as. crucial parameters for the sorption properties of. ionosilicas: the case of chromate adsorption

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1 Supporting Information Surface properties and chemical constitution as crucial parameters for the sorption properties of ionosilicas: the case of chromate adsorption Ut Dong THACH a, Benedicte PRELOT* a, Stéphane PELLET-ROSTAING b, Jerzy ZAJAC a and Peter HESEMANN* a a Institut Charles Gerhardt, UMR-5253 CNRS-UM-ENSCM, Place Eugène Bataillon, F Montpellier cedex 5, FRANCE b Institut de Chimie Séparative, UMR 5257 CNRS-CEA-UM-ENSCM, Site de Marcoule, Bâtiment 426, BP 17171, Bagnols-sur-Cèze Cedex, France Corresponding Author * benedicte.prelot@umontpellier.fr * peter.hesemann@umontpellier.fr S-1

2 Figure S1. BJH desorption pore size distribution of ionosilica A, D, and G Figure S2. BJH desorption pore size distribution of ionosilica A, B, and C S-2

3 Figure S3. Nitrogen adsorption-desorption (left panel) isotherms and BJH (desorption) pore size distribution (right panel) of ionosilica E and F Figure S4. Nitrogen adsorption-desorption isotherms (left panel) and BJH (desorption) pore size distribution (right panel) of ionosilica E and F S-3

4 Figure S5. Nitrogen adsorption-desorption isotherms of ionosilica J S-4

5 Ionosilica B Ionosilica C Ionosilica E Ionosilica F Ionosilica G Ionosilica H Ionosilica I Ionosilica J Figure S6. Scanning electron microscopy pictures of ionosilicas (B to J) used in this study. S-5

6 Figure S7. Sorption isotherms of Cr (VI) onto ionosilicas A, B, C and J (left panel) synthesized from the precursor 1 and the corresponding cumulative enthalpy (right panel) Figure S8. Sorption isotherms of Cr (VI) onto ionosilicas G, H and I (left panel) synthesized from the precursor 3 and the corresponding cumulative enthalpy (right panel) S-6

7 Figure S10. FT-IR Spectra of ionosilica A (prepared with precursor 1 and SHS as template) before and after sorption of Cr(VI). Kinetic study For the various models, the kinetic constants of adsorption were calculated and the linear regression correlation coefficient (R 2 ) values were compared to evaluate the best fit model. The Lagergren-pseudo-first order model 1 can be described by the following linear form: log (1). where q e and q t are the amounts of the dye adsorbed at equilibrium and at time t, respectively; k 1 is the equilibrium rate constant in the pseudo-first order model. Values of k 1 and R 2 were found from the linear plots of log (q e - q t ) versus t. It can be rearranged as The pseudo-second order kinetic model 2 is expressed as follow: 1 (2) (3) where, q e is the amount of the dye adsorbed at equilibrium and k 2 is the equilibrium rate constant in the pseudo-second order model. They can be calculated from the slope of the plot of t/q t versus t. It can be rearranged as (4) The Weber's intra-particle diffusion model 3 equation may write as follows:. (5) S-7

8 where, k id is the equilibrium rate constant of the intra-particle diffusion model. The plots of q t versus t 0.5 should represent straight lines and were used to obtain the rate constants. References 1. Lagergren, S. Zur Theorie Der Sogenannten Adsorption Gelöster Stoffe, Kungliga Svenska Vetenskapsakademiens. Sven. Vetenskapsakad. Handl. 1898, 24, Ho, Y. S.; McKay, G. Pseudo-Second Order Model for Sorption Processes. Process Biochemistry 1999, 34, Ho, Y. S.; McKay, G. Sorption of Dye from Aqueous Solution by Peat. Chem. Eng. J. 1998, 70, S-8