Removal of aqueous toxic Hg(II) by functionalized mesoporous silica materials

Abstract

Background: Hg(II) is one of the most toxic metals and has received particular attention in environmental pollution. Hg(II) pollution is common in water sources, so rapid and efficient methods must be developed for its removal from water samples. Mesoporous silica (MS) is an ideal adsorbent due to its high surface area and biocompatibility. The efficiency and selectivity of MS adsorbents can be improved by surface modification. Results: A new sorbent for trace Hg(II) removal was developed by grafting 1-(3-carboxyphenyl)-2-thiourea (CPTU) onto SBA-15 mesoporous silica. The optimum pH range for Hg(II) adsorption was 3-7 and the maximum static adsorption capacity was 64.5 mg g -1. An enrichment factor of 150 was obtained with a relative standard deviation < 1.5% (n = 8). Common coexisting ions did not interfere with the adsorption of Hg(II) under optimal conditions. Quantitative recovery was achieved by stripping with a mixed solution of 1 mol L -1 HCl and 5% CS(NH 2) 2. Efficient adsorption capacity of the recycled material could still be maintained at a level of 95% at the 7th cycle. Conclusion: 1-(3-carboxyphenyl)-2-thiourea functionalized SBA-15 mesoporous silica was synthesized and applied for Hg(II) removal from water samples with high efficiency and selectivity.