Department of Chemical Engineering, MIT, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA.
Department of Nuclear Engineering, MIT, 77 Massachusetts Avenue, Cambridge, MA, 02139, USA.
Nat Commun. 2018 Nov 8;9(1):4701. doi: 10.1038/s41467-018-07159-0.
The removal of highly toxic, ultra-dilute contaminants of concern has been a primary challenge for clean water technologies. Chromium and arsenic are among the most prevalent heavy metal pollutants in urban and agricultural waters, with current separation processes having severe limitations due to lack of molecular selectivity. Here, we report redox-active metallopolymer electrodes for the selective electrochemical removal of chromium and arsenic. An uptake greater than 100 mg Cr/g adsorbent can be achieved electrochemically, with a 99% reversible working capacity, with the bound chromium ions released in the less harmful trivalent form. Furthermore, we study the metallopolymer response during electrochemical modulation by in situ transmission electron microscopy. The underlying mechanisms for molecular selectivity are investigated through electronic structure calculations, indicating a strong charge transfer to the heavy metal oxyanions. Finally, chromium and arsenic are remediated efficiently at concentrations as low as 100 ppb, in the presence of over 200-fold excess competing salts.
去除高度有毒、超稀释的污染物一直是清洁水技术的主要挑战。铬和砷是城市和农业水中最常见的重金属污染物之一，由于缺乏分子选择性，目前的分离过程存在严重的局限性。在这里，我们报告了用于选择性电化学去除铬和砷的氧化还原活性金属聚合物电极。通过电化学方法可以实现超过 100mg Cr/g 吸附剂的摄取量，具有 99%的可逆工作容量，结合的铬离子以毒性较小的三价形式释放。此外，我们通过原位透射电子显微镜研究了电化学调制过程中的金属聚合物响应。通过电子结构计算研究了分子选择性的潜在机制，表明对重金属含氧阴离子有很强的电荷转移。最后，即使在存在超过 200 倍过量竞争盐的情况下，该金属聚合物也能以低至 100ppb 的浓度有效修复铬和砷。
