In this work, we investigate selective sorption of arsenic from simulated groundwaters at pH 8 by a redox-active polyvinylferrocene (PVF)-functionalized electrode using a modified double potential step chronoamperometry (DPSC) method. Our results show that effective and sustainable As(III) removal can be achieved at 0 V once the electrode is activated via anodic polarization. During activation, ferrocene (Fc) in PVF is oxidized to the ferrocenium ion (Fc⁺) with the latter facilitating As(III) sorption and subsequent oxidation as well as As(V) sorption. The high affinity of Fc⁺ to As and weak attraction to competing anions at 0 V ensure high selectivity of As over Cl^–, SO₄^2–, and NO₃^– at concentrations typical of groundwaters. Following the removal process, efficient regeneration of the electrode is achieved at −1.2 V wherein Fc⁺ is reduced to Fc thereby facilitating As desorption from the electrode surface. Our results further show that O₂ and associated generation of hydrogen peroxide during the regeneration step drive the oxidation of Fc to Fc⁺, thereby maintaining the constant generation of Fc⁺ required to achieve As(III) removal in subsequent cycles. Our results show that 91.8 ± 0.6% of As(III) could be selectively removed from simulated groundwater over 10 cycles at an ultralow energy consumption of 0.12 kWh m^–3.

中文翻译：

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使用氧化还原活性聚乙烯基二茂铁功能化电极从地下水中选择性除砷：氧气的作用。

在这项工作中，我们使用改进的双电势步计时电流法（DPSC）方法研究了氧化还原活性聚乙烯二茂铁（PVF）功能化的电极在pH 8的模拟地下水中选择性吸附砷的能力。我们的结果表明，一旦电极通过阳极极化激活，就可以在0 V下实现有效且可持续的As（III）去除。在活化过程中，PVF中的二茂铁（Fc）被氧化为二茂铁离子（Fc ⁺），后者促进了As（III）的吸附和随后的氧化以及As（V）的吸附。Fc ⁺对As的高亲和力和在0 V下对竞争阴离子的弱吸引力确保了As对Cl ^–，SO ₄ ^2–和NO ₃ ^–的高选择性以典型的地下水浓度。在去除过程之后，在-1.2 V下实现了电极的有效再生，其中Fc ⁺还原为Fc，从而促进了As从电极表面的脱附。我们的结果进一步表明，在再生步骤中O ₂和相关的过氧化氢生成驱动Fc氧化为Fc ⁺，从而维持在随后的循环中实现As（III）去除所需的恒定Fc ⁺生成。我们的结果表明，可以在10个循环内以0.12 kWh m ^–3的超低能耗从模拟地下水中选择性去除91.8±0.6％的As（III）。