Removal of aqueous Hg(ii) by thiol-functionalized nonporous silica microspheres prepared by one-step sol-gel method

It is well known that thiol-functionalized silica (SiO₂-SH) can be used as an effective adsorbent for the removal of Hg(ii) from water. Studies in this field have focused on porous silica gels and mesoporous silicas that have large surface area and pore volume, while nonporous silica particles are seldom reported. This work aims to investigate the Hg(ii) adsorption properties of nonporous SiO₂-SH microspheres prepared by a simple one-step sol-gel method. The effects of pH, initial concentration of Hg(ii) and temperature on the adsorption properties of the SiO₂-SH microspheres were studied via batch adsorption experiments. The maximum adsorption capacity for Hg(ii) at 293 K calculated from the Langmuir equation was 377.36 mg g^-1. The adsorption kinetics and equilibrium data were well-fitted to the pseudo-second-order model and the Langmuir isotherm model, respectively.