Department of Civil & Environmental Engineering University of California, Berkeley, Berkeley, California 94720, United States.
Environ Sci Technol. 2023 Nov 28;57(47):18680-18689. doi: 10.1021/acs.est.2c08404. Epub 2023 Mar 16.
Low-cost stainless-steel electrodes can activate hydrogen peroxide (HO) by converting it into a hydroxyl radical (OH) and other reactive oxidants. At an applied potential of +0.020 V, the stainless-steel electrode produced OH with a yield that was over an order of magnitude higher than that reported for other systems that employ iron oxides as catalysts under circumneutral pH conditions. Decreasing the applied potential at pH 8 and 9 enhanced the rate of HO loss by shifting the process to a reaction mechanism that resulted in the formation of an Fe(IV) species. Significant metal leaching was only observed under acidic pH conditions (i.e., at pH <6), with the release of dissolved Fe and Cr occurring as the thickness of the passivation layer decreased. Despite the relatively high yield of OH production under circumneutral pH conditions, most of the oxidants were scavenged by the electrode surface when contaminant concentrations comparable to those expected in drinking water sources were tested. The stainless-steel electrode efficiently removed trace organic contaminants from an authentic surface water sample without contaminating the water with Fe and Cr. With further development, stainless-steel electrodes could provide a cost-effective alternative to other HO activation processes, such as those by ultraviolet light.
低成本的不锈钢电极可以通过将过氧化氢（HO）转化为羟基自由基（OH）和其他活性氧化剂来激活 HO。在施加的电位为+0.020 V 的情况下，不锈钢电极产生 OH 的产率比其他在中性 pH 条件下使用氧化铁作为催化剂的系统报告的产率高出一个数量级以上。在 pH 8 和 9 下降低施加的电位会通过将过程转移到导致形成 Fe(IV)物种的反应机制来增强 HO 损失的速率。只有在酸性 pH 条件下（即 pH <6）才会观察到明显的金属浸出，随着钝化层厚度的减小，溶解的 Fe 和 Cr 释放。尽管在中性 pH 条件下 OH 的产生产率相对较高，但当测试与饮用水源中预期的浓度相当的污染物浓度时，电极表面会捕获大部分氧化剂。不锈钢电极有效地从真实的地表水样品中去除痕量有机污染物，而不会使 Fe 和 Cr 污染水。随着进一步的发展，不锈钢电极可以为 HO 激活过程提供一种具有成本效益的替代方案，例如紫外线。
