Ultraeffective ZnS Nanocrystals Sorbent for Mercury(II) Removal Based on Size-Dependent Cation Exchange

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• 作者：Zan Qu ; Lili Yan ; Liang Li ; Jianfang Xu ; Mingming Liu ; Zhichun Li ; Naiqiang Yan
• 刊名：ACS Applied Materials & Interfaces
• 出版年：2014
• 出版时间：October 22, 2014
• 年：2014
• 卷：6
• 期：20
• 页码：18026-18032
• 全文大小：396K
• ISSN：1944-8252

文摘

We report a novel nanocrystals (NCs) sorbent, which shows an extraordinary adsorption capacity to aqueous Hg²⁺ based on cation exchange and allows for the utmost removal of mercury from water. The NCs sorbent was synthesized by direct coating ZnS NCs on the surface of the 伪-Al₂O₃ nanoparticles. The as-prepared ZnS NCs sorbent can efficiently remove over 99.9% Hg²⁺ in 1 min, and lower the Hg²⁺ concentration from 297.5 mg/L (ppm) to below 1.0 渭g/L (ppb) within 5 min. The saturated adsorption capacity of ZnS NCs for Hg²⁺ is about 2000 mg/g, which is close to the theoretic saturated adsorption capacity. The mechanism of Hg²⁺ removal by ZnS NCs sorbent, the influences of pH value and other cations on Hg²⁺ removal were investigated, respectively. Meanwhile, it is found the size-dependent cation exchange plays a critical role in the removal of Hg²⁺ by ZnS NCs. Small size ZnS NCs shows better performance than the big size ZnS NCs in the adsorption capacity and adsorption rate for Hg²⁺. Furthermore, the mercury adsorbed by the ZnS NCs sorbent is readily recycled by extraction with aqueous sodium sulfide.

Keywords:

nanocrystals; mercury removal; cation exchange; size-dependent; ZnS sorbents