Environmental Engineering Program, Department of Civil Engineering, Auburn University , Auburn, Alabama 36849, United States.
Environ Sci Technol. 2014 Apr 1;48(7):3986-94. doi: 10.1021/es404418a. Epub 2014 Mar 11.
Iron sulfide (FeS) nanoparticles were prepared with sodium carboxymethyl cellulose (CMC) as a stabilizer, and tested for enhanced removal of aqueous mercury (Hg(2+)). CMC at ≥0.03 wt % fully stabilized 0.5 g/L of FeS (i.e., CMC-to-FeS molar ratio ≥0.0006). FTIR spectra suggested that CMC molecules were attached to the nanoparticles through bidentate bridging and hydrogen bonding. Increasing the CMC-to-FeS molar ratio from 0 to 0.0006 enhanced mercury sorption capacity by 20%; yet, increasing the ratio from 0.0010 to 0.0025 diminished the sorption by 14%. FTIR and XRD analyses suggested that precipitation (formation of cinnabar and metacinnabar), ion exchange (formation of Hg0.89Fe0.11S), and surface complexation were important mechanisms for mercury removal. A pseudo-second-order kinetic model was able to interpret the sorption kinetics, whereas a dual-mode isotherm model was proposed to simulate the isotherms, which considers precipitation and adsorption. High mercury uptake was observed over the pH range of 6.5-10.5, whereas significant capacity loss was observed at pH < 6. High concentrations of Cl(-) (>106 mg/L) and organic matter (5 mg/L as TOC) modestly inhibited mercury uptake. The immobilized mercury remained stable when preserved for 2.5 years at pH above neutral.
硫化亚铁（FeS）纳米颗粒采用羧甲基纤维素钠（CMC）作为稳定剂进行制备，并对其增强去除水溶液中汞（Hg(2+)）的性能进行了测试。CMC 含量≥0.03wt%时可完全稳定 0.5g/L 的 FeS（即 CMC 与 FeS 的摩尔比≥0.0006）。FTIR 谱图表明 CMC 分子通过双齿桥连和氢键与纳米颗粒结合。CMC 与 FeS 的摩尔比从 0 增加到 0.0006 时，汞的吸附容量增加了 20%；然而，当该比值从 0.0010 增加到 0.0025 时，吸附量减少了 14%。FTIR 和 XRD 分析表明，沉淀（形成辰砂和汞黝铜矿）、离子交换（形成 Hg0.89Fe0.11S）和表面络合是去除汞的重要机制。拟二级动力学模型能够解释吸附动力学，而提出的双模式等温模型用于模拟考虑沉淀和吸附的等温线。汞的高去除率观察到在 pH 范围 6.5-10.5 之间，而在 pH<6 时观察到容量损失显著。高浓度的 Cl-（>106mg/L）和有机物（TOC 为 5mg/L）适度抑制了汞的摄取。在中性以上 pH 值下保存 2.5 年时，固定化的汞仍保持稳定。
