School of Environmental Science and Engineering, Shanghai Jiao Tong University , Shanghai 200240, China.
ACS Appl Mater Interfaces. 2014 Oct 22;6(20):18026-32. doi: 10.1021/am504896w. Epub 2014 Oct 9.
We report a novel nanocrystals (NCs) sorbent, which shows an extraordinary adsorption capacity to aqueous Hg(2+) 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 α-Al2O3 nanoparticles. The as-prepared ZnS NCs sorbent can efficiently remove over 99.9% Hg(2+) in 1 min, and lower the Hg(2+) concentration from 297.5 mg/L (ppm) to below 1.0 μg/L (ppb) within 5 min. The saturated adsorption capacity of ZnS NCs for Hg(2+) is about 2000 mg/g, which is close to the theoretic saturated adsorption capacity. The mechanism of Hg(2+) removal by ZnS NCs sorbent, the influences of pH value and other cations on Hg(2+) removal were investigated, respectively. Meanwhile, it is found the size-dependent cation exchange plays a critical role in the removal of Hg(2+) by ZnS NCs. Small size ZnS NCs shows better performance than the big size ZnS NCs in the adsorption capacity and adsorption rate for Hg(2+). Furthermore, the mercury adsorbed by the ZnS NCs sorbent is readily recycled by extraction with aqueous sodium sulfide.
我们报告了一种新型纳米晶体（NCs）吸附剂，它基于阳离子交换表现出非凡的水相中 Hg(2+)吸附能力，可最大限度地从水中去除汞。NCs 吸附剂是通过将 ZnS NCs 直接涂覆在α-Al2O3 纳米颗粒表面合成的。所制备的 ZnS NCs 吸附剂可在 1 分钟内有效去除超过 99.9%的 Hg(2+)，并在 5 分钟内将 Hg(2+)浓度从 297.5mg/L（ppm）降低到 1.0μg/L（ppb）以下。ZnS NCs 对 Hg(2+)的饱和吸附容量约为 2000mg/g，接近理论饱和吸附容量。研究了 ZnS NCs 吸附剂去除 Hg(2+)的机制、pH 值和其他阳离子对 Hg(2+)去除的影响。同时，发现尺寸依赖性的阳离子交换在 ZnS NCs 去除 Hg(2+)中起着关键作用。小尺寸 ZnS NCs 在吸附容量和 Hg(2+)吸附速率方面表现出比大尺寸 ZnS NCs 更好的性能。此外，ZnS NCs 吸附剂吸附的汞可以通过用硫化钠水溶液萃取来轻易回收。
