Investigation on into the adsorption of Cu(II), Pb(II) and Cr(VI) on hollow mesoporous silica using microcalorimetry

Abstract

Hollow mesoporous silica (SiO2) was synthesized by the modified self-template method, and the morphology and structural properties of mesoporous silica were characterized by XRD, SEM, TEM, BET. Microcalorimetry was employed to investigate the adsorption behavior of Cu(II), Pb(II) and Cr(VI) from aqueous solution. The results showed that ΔH and ΔS were both less than zero (ΔH < 0, ΔS < 0) during the adsorption process, and van der Waals forces were the driving force for adsorption. The adsorption curves of Cu(II) and Pb(II) by HMSS accord with the Langmuir adsorption isotherm, and the adsorption curve of HMSS to Cr(VI) accords with the Freundlich adsorption isotherm. Monte Carlo simulation showed that Cu(II), Pb(II), Cr(VI) were adsorbed on the surface of this nanomaterial and in the interstitial positions between the atoms. The adsorption energy of molecular simulation is consistent with the experimental results.