Textile Pollution Controlling Engineering Center of Ministry of Environmental Protection, College of Environmental Science and Engineering, Donghua University , 2999 North Renmin Road , Shanghai 201620 , P. R. China.
Shanghai Institute of Pollution Control and Ecological Security , 1239 Siping Road , Shanghai 200092 , P. R. China.
Environ Sci Technol. 2019 Feb 5;53(3):1527-1535. doi: 10.1021/acs.est.8b05936. Epub 2019 Jan 17.
Herein, we rationally designed a dual-functional electroactive filter system for simultaneous detoxification and sequestration of Sb(III). Binder-free and nanoscale TiO-modified carbon nanotube (CNT) filters were fabricated. Upon application of an external electrical field, in situ transformation of Sb(III) to less toxic Sb(V) can be achieved, which is further sequestered by TiO. Sb(III) removal kinetics and capacity increase with applied voltage and flow rate. This can be explained by the synergistic effects of the filter's flow-through design, electrochemical reactivity, small pore size, and increased number of exposed sorption sites. STEM characterization confirms that Sb were mainly sequestered by TiO. XPS, AFS, and XAFS results verify that the Sb(III) conversion process was accelerated by the electrical field. The proposed electroactive filter technology works effectively across a wide pH range. The presence of sulfate, chloride, and carbonate ions negligibly inhibited Sb(III) removal. Exhausted TiO-CNT filters can be effectively regenerated using NaOH solution. At 2 V, 100 μg/L Sb(III)-spiked tap water generated ∼1600 bed volumes of effluent with >90% efficiency. Density functional theory calculations suggest that the adsorption energy of Sb(III) onto TiO increases (from -3.81 eV to -4.18 eV) and Sb(III) becomes more positively charged upon application of an electrical field.
在这里，我们合理设计了一种双功能电活性过滤系统，用于同时解毒和螯合 Sb(III)。制备了无粘合剂和纳米级 TiO 修饰的碳纳米管 (CNT) 过滤器。施加外部电场后，可将 Sb(III)原位转化为毒性较小的 Sb(V)，然后进一步被 TiO 螯合。Sb(III)的去除动力学和容量随施加电压和流速的增加而增加。这可以通过过滤器的直通式设计、电化学反应性、小孔径和增加的暴露吸附位点数量的协同效应来解释。STEM 表征证实 Sb 主要被 TiO 螯合。XPS、AFS 和 XAFS 结果验证了电场加速了 Sb(III)的转化过程。所提出的电活性过滤技术在很宽的 pH 范围内都能有效工作。硫酸盐、氯化物和碳酸盐离子的存在对 Sb(III)的去除抑制作用可以忽略不计。用过的 TiO-CNT 过滤器可以使用 NaOH 溶液有效再生。在 2 V 时，100 μg/L Sb(III)污染的自来水产生了约 1600 倍床体积的出水，效率超过 90%。密度泛函理论计算表明，施加电场后，Sb(III)在 TiO 上的吸附能增加（从-3.81 eV 增加到-4.18 eV），Sb(III)带正电荷的程度增加。
