Selective mesoporous adsorbents for and Cu2+ separation

Abstract: NH2–MCM-41 and COONa–MCM-41 were prepared by grafting aminopropyls and propionates on the pore wall of the mesoporous silica MCM-41 for the separation of and Cu2+. Single and binary component adsorptions show that has a 100% selectivity for adsorption at low pH (<3.5 i.e., point of zero charge, p.z.c.), while COO−Na+–MCM-41 adsorbs only Cu2+ over the entire pH range of the study (i.e., pH 1.5–5.5). Adsorption uptakes were rapid on both adsorbents reaching equilibrium in less than 3h and in most cases less than 10min. The adsorption capacity of for is high, approaching the theoretical values of two aminopropyls for one , the Cu2+ adsorption on COO−Na+–MCM-41 was less efficient requiring five propionates to adsorb one Cu2+. High purity hydrogen dichromate and copper chloride solutions were respectively recovered by a simple acid wash and the regenerated adsorbents were reused without a loss of performance. [Copyright &y& Elsevier]