Department of Environmental Engineering, Zhejiang University, Hangzhou, 310029, People's Republic of China.
Environemtal Science Research & Design Institute of Zhejiang Province, Hangzhou, 310007, People's Republic of China.
Environ Res. 2020 Aug;187:109662. doi: 10.1016/j.envres.2020.109662. Epub 2020 May 19.
Sulfide-modified nanoscale zerovalent iron (S-nZVI) has excellent reducing performance for heavy metals in water. The influence of environmental factors on the reactivity can be used to explore the practical feasibility of S-nZVI and analyze the reaction mechanism in depth. This study compared the removal effect and mechanism of Cu and Ni by nanoscale zerovalent iron (nZVI), S-nZVI, and carboxymethyl cellulose-modified nanoscale zerovalent iron (CMC-nZVI). The results show that the pseudo-first-order kinetic constant of Cu removal by nZVI, S-nZVI, and CMC-nZVI was 1.384, 1.919, and 2.890 min, respectively, and the rate of Ni removal was 0.304, 0.931, and 0.360 min, respectively. The removal mechanism of S-nZVI was similar to that of nZVI and CMC-nZVI. Specifically, Cu was predominantly removed by reduction, while Ni removal included adsorption and reduction. Environmental factors had a specific inhibitory effect on the removal of Cu but had a negligible impact on Ni. The condition of low pH, the presence of Cl and humic acid (HA) promoted the corrosion consumption of Fe, in which H directly corroded Fe at low pH. At the same time, Cl and HA inhibited the adsorption or binding of heavy metal ions on the particle surface, thereby reducing the electron transfer and utilization efficiency. The passivation of NO reduced the anaerobic corrosion of the material in water but suppressed the release of electrons, thereby reducing the reduction efficiency of the three types of materials. The anaerobic corrosion of S-nZVI was less affected by environmental factors, and it can still maintain more than 80% of the electronic utilization efficiency under different environmental factors, which illustrates that S-nZVI has broad prospects for practical applications in heavy metal polluted water.
硫化纳米零价铁（S-nZVI）对水中重金属具有优异的还原性能。通过研究环境因素对其反应活性的影响，可以深入探究 S-nZVI 的实际可行性，并分析其反应机制。本研究比较了纳米零价铁（nZVI）、S-nZVI 和羧甲基纤维素改性纳米零价铁（CMC-nZVI）对 Cu 和 Ni 的去除效果和机制。结果表明，nZVI、S-nZVI 和 CMC-nZVI 去除 Cu 的准一级动力学常数分别为 1.384、1.919 和 2.890 min-1，去除 Ni 的速率分别为 0.304、0.931 和 0.360 min-1。S-nZVI 的去除机制与 nZVI 和 CMC-nZVI 相似，主要通过还原作用去除 Cu，而 Ni 的去除则包括吸附和还原。环境因素对 Cu 的去除具有特定的抑制作用，但对 Ni 的去除影响较小。低 pH、Cl 和腐殖酸（HA）的存在促进了 Fe 的腐蚀消耗，其中 H 在低 pH 下直接腐蚀 Fe。同时，Cl 和 HA 抑制了重金属离子在颗粒表面的吸附或结合，从而降低了电子转移和利用效率。NO 的钝化降低了材料在水中的厌氧腐蚀，但抑制了电子的释放，从而降低了三种材料的还原效率。S-nZVI 的厌氧腐蚀受环境因素的影响较小，在不同的环境因素下仍能保持 80%以上的电子利用效率，说明 S-nZVI 在重金属污染水的实际应用中具有广阔的前景。
