Synthesis, characterization and metal adsorption properties of the new ion exchanger polymer 3-n-propyl(4-methylpyridinium) silsesquioxane chloride

The preparation and anion exchange properties of 3-n-propyl(4-methylpyridinium) silsesquioxane chloride polymer are described. This new polymer was prepared by the sol-gel processing method and is designated as SiPic(+)Cl(-). It is insoluble in water and showed an anion exchange capacity of 1.46 x 10(-3) molg(-1). The adsorption isotherms of ZnCl(2), CdCl(2) and HgCl(2) were determined from aqueous solutions and the adsorption equilibria simulations fit the model of fixed bidentate centers with the absence of lateral interactions and energetic heterogeneity between them. The metal ions diffuse into the solid solution interface and are dominantly present as MCl(4)(2-) species for Zn(II), MCl(4)(2-) and MCl(3)(-) species for Cd(II) and MCl(3)(-) species for Hg(II). (c) 2006 Elsevier Inc. All rights reserved.3031182

Simulation of adsorption equilibria on hybrid materials: Binding of metal chlorides with 3-n-propylpyridinium silsesquioxane chloride ion exchanger

The quantitative description of cooperativity effects at binding of low-molecular reagents with active reactive centers of hybrid materials requires the elaboration of convenient and reliable meaningful models and calculation procedures. The model of fixed polydentate centers was analyzed as a prospective tool for simulation of adsorption equilibria. The model was shown to be flexible and adaptive. At the theoretic foundations, it is equivalent or more general as compared with another approaches. The procedure for constructing the models fitting the experimental data. within their errors and the corresponding calculation tools were discussed. The special attention was paid to the problem of simultaneous determination of sorption capacities and equilibrium constants. To overcome this difficulty the strategy involving the fuzzy sets theory was proposed. The elaborated methods were used to characterize a new material, 3-n-propylpyridinium silsesquioxane chloride ion exchanger. Adsorption of Fe(III), Cu(II), Zn(II), Cd(II), and Hg(II) chlorides by the material from ethanol solutions was studied at 298 K. The material was found to possess a high affinity to metal chlorides. The sorption capacities of the material and the constants of adsorption equilibria were determined. The material demonstrates the following order of affinity: FeCl3 > CuCl2, HgCl2 > CdCl2 > ZnCl2. On the base of simulation, the negative cooperativity in the case of the CuCl2 adsorption was concluded, while adsorption of other chlorides is accompanied by the positive cooperativity. (c) 2007 Elsevier Inc. All rights reserved.3101475

Surface functionalization of SBA-15 and a nonordered mesoporous silica with a 1,4-diazabicyclo[2.2.2]octane derivative: Study of CuCl2 adsorption from ethanol solution

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)This work describes the preparation and characterization of postfunctionalized ordered (SBA-15) and nonordered (SMD) mesoporous silicas with n-propyl-1,4-diazoniabicycle[2.2.2]octane chloride (DbCl) moiety. The main interest is based on the fact that these materials are excellent adsorbents due to the ability of functional groups to retain copper chlorides on their surfaces as anionic complexes CuCl2+nn-. The specific surface areas (S-BET) and average pore diameters (d(pore)) for SBA-15 and SMD are SBA-15, S-BET = 944 m(2) g(-1), d(pore) = 9.0 nm; SMD, S-BET = 710 m(2) g(-1), d(pore) = 11 nm. On functionalization with DbCl, reductions in the specific surface areas of the resulting materials (SBA-15/DbCl and SMD/DbCl) are observed and the following functionalization degrees (phi) were determined: SBA-15/DbCl, S-BET = 247 m(2) g(-1), phi = 0.95 mmol g(-1); SMD/DbCl, S-BET = 83 m(2) g(-1), phi = 1.2 mmol g(-1). The adsorption equilibria of CuCl2 in ethanol were characterized, and the heterogeneous stability constants, beta(1) and beta(2), corresponding to formation of CuCl42- and CuCl3- anionic species adsorbed on the surface were found. Also, the effective sorption capacities (t(Q)) were determined: SBA-15/DbCl, log beta(1) = 4.46, log beta(2) = 7.10, t(Q) = 0.80 mmol g(-1); SMD/DbCl, log beta(1) = 4.95, log beta(2) = 7.52, t(Q) = 0.75 mmol g(-1). Regeneration of the adsorbents requires a very simple procedure consisting of their immersion in aqueous solution followed by immediate release to the solution phase of the Cu(OH2)(n)(2+) species, followed by chloride anions as the counterions. (C) 2011 Published by Elsevier Inc.3561248256Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP