Thiol-functionalized hierarchical zeolite nanocomposite for adsorption of Hg2+ from aqueous solutions

A thiol-functionalized hierarchical zeolite nanocomposite was synthesized and investigated with a view to remove mercury from aqueous solutions. The hierarchical zeolite was prepared by the use of a beta zeolite and of cetyltrimethylammoniumbromide (CTAB). The ligand, 3-mercaptopropyltrimethoxysilane containing thiol (-SH) groups, was then immobilized on the surface of the hierarchical zeolite through grafting with surface silanol groups. FTIR, XRD, SEM, TG-DTG, and N-2 adsorption-desorption techniques were used to characterize the nanocomposite before and after functionalization. Adsorption experiments showed that this adsorbent was an excellent one to bind mercury with high selectivity; an adsorption capacity of 8.2 mequiv.g(-1) of adsorbent was obtained. Furthermore, the adsorbent retained most of its capacity after regeneration with nitric acid and thiourea solutions. The adsorption data was fitted to the Freundlich isotherm. (C) 2014 Academie des sciences. Published by Elsevier Masson SAS. All rights reserved.