Effect of SH/SBA-15 Molar Ratio on Pb(II) and Cd(II) Ions Adsorption from Aqueous Solution by Mercaptopropyl-grafted SBA-15 Mesoporous Material as Adsorbent

The purposes of the current study were to investigate the adsorption of Pb(II) and Cd(II) from aqueous solution by thiol-functionalized SBA-15 materials designed by SBA-15-SH (x) where x is the SH/SBA-15 molar ratio, which corresponds to the introduced moles number of Mercapto moieties to that of siliceous of the SBA-15 materials. Furthermore, these materials were synthesized using 3-Mercaptopropyltrimethoxysilane (MPTMS) via post-grafting approach. SBA-15-SH(x) materials were characterized by XRD, N2 adsorption-desorption and FT-IR. The incorporation of SH fragments was proved by FT-IR Spectroscopy, thermogravimetric analysis (TGA) and solid state 13C and 29Si NMR Spectroscopy.The removal of lead ions is more important than that of cadmium ions. Furthermore, the lead removal on SBA-15-SH(x) increased with the increase of SH/SBA-15 molar ratio (removal rate of 28.5, 71.3, and 96.8 % for SH/SBA-15 molar ratio=0.35, 0.7 and 1.4, respectively) while the removal of cadmium was not affected (around 57 % removal rate for all molar ratios). The post-grafting of Mercaptopropyl fragments onto the surface of SBA-15 mesoporous material was achieved putting different amounts which correspond to SH/SBA-15 molar ratio equal to 0.35; 0.7 and 1.4, respectively. Therefore, materials were characterized by different analyzes. All characterization results show the successful introduction of thiol groups, but the textural properties were reduced as comparing with SBA-15.In another hand, the incorporation of thiol moieties onto the surface of SBA-15 brings an additional preference towards lead ions adsorption compared to cadmium ions.image