Hypophosphorous acid functionalized nanoporous silicon for selective adsorption of Hg(II) in industrial waste water

Abstract

The recycling of diamond wire cutting silicon waste (DWCSW) and the removal of heavy metal ions are very important for human life. Therefore, it is a promising method to improve the selective removal of heavy metal ions by etching and modifying organic functional groups for DWCSW. In this study, a new adsorbent PA-TEPA-GTS-NPSi was synthesized by Cu-assisted chemical etching and modified with 3-glycine dioxy-propyl trimethoxy-silane (3-GTS), tetraethylpentenediamine (TEPA) and hypophosphorous acid (H3PO2) for selective adsorption Hg(Ⅱ). PA-TEPA-GTS-NPSi showed excellent adsorption performance on Hg(Ⅱ), with adsorption capacity of 112.8 mg/g (pH=2.0, adsorption time=120 min). The pseudo-second-order model and Langmuir model can better describe the adsorption process, which proving that the adsorption process is chemisorption. The adsorption mechanism of Hg(Ⅱ) was studied by X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT). It was proved that the adsorption process was mainly caused by the strong adsorption between P and Hg(Ⅱ) in the phosphorus groups on the surface of PA-TEPA-GTS-NPSi adsorbent. Compared with other hypophosphorous acid functionalized adsorbents, the adsorption performance of the adsorbent is at a medium level, but it can effectively recycle DWCSW while removing heavy metal ions.