Department of Chemistry, Zhejiang Sci-tech University, Hangzhou, 310018, PR China.
Department of Chemistry, Zhejiang Sci-tech University, Hangzhou, 310018, PR China.
Chemosphere. 2022 May;294:133806. doi: 10.1016/j.chemosphere.2022.133806. Epub 2022 Feb 1.
Ammonium as the major reduction intermediate has always been the limitation of nitrate reduction by cathodic reduction or nano zero-valent iron (nZVI). In this work, we report the electrochemical nitrate removal by magnetically immobilized nZVI anode on RuO-IrO/Ti plate with ammonia-oxidizing function. This system shows maximum nitrate removal efficiency of 94.6% and nitrogen selectivity up to 72.8% at pH of 3.0, and it has also high nitrate removal efficiency (90.2%) and nitrogen selectivity (70.6%) near neutral medium (pH = 6). As the increase of the applied anodic potentials, both nitrate removal efficiency (from 27.2% to 94.6%) and nitrogen selectivity (70.4%-72.8%) increase. The incorpration of RuO-IrO/Ti plate with ammonia-oxidizing function on the nZVI anode enhances the nitrate reduction. The dosage of nZVI on RuO-IrO/Ti plate (from 0.2 g to 0.6 g) has a slight effect (the variance is no more than 10.0%) on the removal performance. Cyclic voltammetry, Tafel analysis and electrochemical impedance spectroscopy (EIS) were further used to investigate the reaction mechanisms occurring on the nZVI surfaces in terms of CV curve area, corrosion voltage, corrosion current density and charge-transfer resistance. In conclusion, high nitrate removal performance of magnetically immobilized nZVI anode coupled with RuO-IrO/Ti plate may guide the design of improved electrochemical reduction by nZVI-based anode for practical nitrate remediation.
铵作为主要的还原中间产物，一直是阴极还原或纳米零价铁（nZVI）还原硝酸盐的限制因素。在这项工作中，我们报告了在 RuO-IrO/Ti 板上固定化 nZVI 阳极电化学去除硝酸盐的情况，该阳极具有氨氧化功能。在 pH 为 3.0 时，该系统的硝酸盐去除效率最高可达 94.6%，氮选择性最高可达 72.8%，在近中性介质（pH = 6）时也具有较高的硝酸盐去除效率（90.2%）和氮选择性（70.6%）。随着施加阳极电势的增加，硝酸盐去除效率（从 27.2%提高到 94.6%）和氮选择性（70.4%-72.8%）都有所提高。在 nZVI 阳极上结合具有氨氧化功能的 RuO-IrO/Ti 板增强了硝酸盐的还原。在 RuO-IrO/Ti 板上的 nZVI 用量（从 0.2 g 到 0.6 g）对去除性能的影响很小（变化不超过 10.0%）。进一步使用循环伏安法、塔菲尔分析和电化学阻抗谱（EIS）来研究 CV 曲线面积、腐蚀电压、腐蚀电流密度和电荷转移电阻等方面发生在 nZVI 表面的反应机制。总之，与 RuO-IrO/Ti 板结合的固定化 nZVI 阳极具有较高的硝酸盐去除性能，可能为基于 nZVI 的阳极的实际硝酸盐修复的改进电化学还原设计提供指导。
