Adsorption enhancement of elemental mercury onto sulphur-functionalized silica gel adsorbents

Abstract

In this study, elemental mercury (EM) adsorbents were synthesized using tetraethyl orthosilicate (TEOS) and 3-mercaptopropyl trimethoxysilane as silica precursors. The synthesized silica gel (SG)-TEOS was further functionalized through impregnation with elemental sulphur and carbon disulphide (CS 2). The SG adsorbents were then characterized by using scanning electron microscope, Fourier transform infra-red spectrophotometer, nitrogen adsorption/desorption, and energy-dispersive X-ray diffractometer. The EM adsorption of the SG adsorbents was determined using fabricated fixed-bed adsorber. The EM adsorption results showed that the sulphur-functionalized SG adsorbents had a greater Hg° breakthrough adsorption capacity, confirming that the presence of sulphur in silica matrices can improve Hg° adsorption performance due to their high affinity towards mercury. The highest Hg° adsorption capacity was observed for SG-TEOS(CS2) (82.62 g/g), which was approximately 2.9 times higher than SG-TEOS (28.47 g/g). The rate of Hg° adsorption was observed higher for sulphur-impregnated adsorbents, and decreased with the increase in the bed temperatures