Rapid and selective removal of Hg(II) ions and high catalytic performance of the spent adsorbent based on functionalized mesoporous silica/poly(m-aminothiophenol) nanocomposite

The toxic Hg(II) being released excessively into the water body from various sources has threatened the environment and human health. The aim of this study is to design a rapid and selective adsorbent, and propose an alternative way to dispose the spent adsorbent. To this end, a new material ( MAP ) was designed by inducing the polymerization of m -aminothiophenol onto MCM-41 (Mobil Composition of Matter) surface obtained using cheap diatomite as a silica source and modified by APTES ((3-aminopropyl) triethoxysilane), and the spent adsorbent was further converted into an active catalyst for acetophenone synthesis. The adsorption properties of the MAP were systematically explored under different parameters, and the corresponding results were analyzed based on different adsorption kinetic and isotherm models. The study found the removal rate and adsorption capacity of the MAP could reach 96.56% and 242.42   mg/g within 15   min. The coexisting cations showed little competition effect on the removal of Hg(II), and the adsorption capacities after five cycles did not obviously decrease. Kinetic study indicated that the adsorption data were well fitted to the pseudo-second-order model, and the adsorption equilibrium data followed the Langmuir model. After adsorption studies, the Hg(II)- MAP was used as a catalyst in the reaction of phenylacetylene to acetophenone with high yield of 97.01%. This work not only provides a rapid and selective adsorbent for removal of Hg(II) ions, but also opens a novel avenue for reusing the toxic spent adsorbent for catalytic application.