Sulfur crosslinked poly(m-aminothiophenol)/potato starch on mesoporous silica for efficient Hg(II) removal and reutilization of waste adsorbent as a catalyst

Abstract

Elemental sulfur, as a by-product of petroleum refining, is regarded as a solid waste stored in above-ground deposits due to limited existing applications, meanwhile, mercury contamination is one of the current environmental issues considering its high toxicity to the human, and how to safely dispose of hazardous waste adsorbents is still an unavoidable problem. This study addresses these need by utilizing sulfur for preparation of a polysulfide complex material to capture Hg(II) and convert the Hg(II)-containing spent adsorbent into a catalyst. Initially, the mesoporous silica was prepared and functionalized by using diatomite and APTES, then, an in-situ preparation method was applied to obtain the amine-mesoporous silica/poly(m-aminothiophenol) nanocomposite (MAP), subsequently sulfur was copolymerized with MAP and vinylic-potato starch through inverse vulcanization, forming the sulfur crosslinked polymers composite cp(MAP-S-PS). Many characterizations were employed to determine the physicochemical structure and morphology of cp(MAP-S-PS). The adsorption study showed the cp(MAP-S-PS) exhibited the theoretical maximum adsorption capacity of 436.68 mg/g, good regeneration performance after 5 cycles and excellent selectivity between Hg(II) ions and common cations. Furthermore, the collected spent adsorbent cp(MAP-S-PS)/Hg(II) was reused as a catalyst for synthesis of acetophenone with 89% yield, and most of phenylacetylene derivatives were also transformed to corresponding acetophenone in good yields.