Synthesis and characterization of mesoporous silicas functionalized by thiol groups, and application as sorbents for mercury (Ⅱ)

摘要

Heavy metal ion (Hg~Ⅱ) adsorbents with uniform mesopore channels were prepared by functionalizing SB A-15 and SB A-16 type ordered mesoporous silica samples with mercaptopropyl groups according to two routes: post synthesis grafting of pure mesoporous silica and direct functionalization by a co-condensation procedure. XRD, N_2 adsorption-desorption measurements and ~(29)Si solid state NMR spectroscopy were used to characterize the physico-chemical properties of the organic-inorganic hybrid materials and to investigate the different functionalization processes on the two types of ordered mesoporous silica SB A-15 and SB A-16 materials. Higher contents in organo-functional groups were achieved when following the one-step co-condensation route in comparison with the post-synthesis grafting. However, the evaluation of the diffusion rates of Hg~Ⅱ species in the mesoporous solids by means of an electrochemical method showed faster binding rates for the post-synthesis grafted samples.