Hu Haiyang, Luo Jiayu, He Linyu, Lei Yang
Shenzhen Key Laboratory of Precision Measurement and Early Warning Technology for Urban Environmental Health Risks, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China.
Shenzhen Key Laboratory of Precision Measurement and Early Warning Technology for Urban Environmental Health Risks, School of Environmental Science and Engineering, Southern University of Science and Technology, Shenzhen, 518055, China.
Water Res. 2025 May 1;275:123195. doi: 10.1016/j.watres.2025.123195. Epub 2025 Jan 23.
Iron electrocoagulation (Fe-EC) exhibits broad application in water remediation towards various pollutants, including emerging organic phosphorus compounds (i.e., phosphonates). However, it suffers relatively high costs due to the frequent replacement of iron anode consumables, particularly electrode fouling. Here we report an iron scrap packed-bed (ISPB) anode electrocoagulation (EC) system for efficiently removing phosphonate. In NaSO, NaCl and NaHCO electrolytes, the ISPB-EC system effectively removed 39-99% of nitrilotrimethylene triphosphonic acid (NTMP) with 0.1 mM total soluble phosphorus (TSP) concentration at a coulombic dosage of 144 C/L. In contrast, only 2-23% NTMP was eliminated with conventional Fe-EC under identical conditions. We also found the partial conversion of NTMP to inorganic phosphate, primarily attributed to the formation of HO· and Fe(IV)O during the oxidation of Fe in the ISPB-EC system. We further validated the adaptability and robust efficacy of ISPB-EC in realistic conditions, including actual cooling water (ACW). Our cost calculation suggests that the new system achieves a lower cost (€0.0067/m) in treating NTMP-loaded ACW than the traditional Fe-EC system (€0.009/m). Moreover, we addressed the scaling issue in the newly developed ISPB-EC system. We did not notice apparent cathode scaling over short-term batch tests. However, orange-red scales gradually formed on the cathode in the continuous flow experiment, accompanied by an increased cell voltage. To this end, we proposed and validated the strategy of periodic polarity reversal in alleviating the cathode scaling. Notably, the voltage can be reduced to the initial level by refilling the iron scrap after eliminating cathode fouling through polarity reversal, realizing the long-term stable operation of the ISPB-EC system over 336 h. Our work established an affordable, highly efficient electrocoagulation system using cheap waste iron scrap electrodes to treat phosphonates-contained wastewater.
铁电凝（Fe-EC）在水修复中对包括新兴有机磷化合物（即膦酸盐）在内的各种污染物具有广泛应用。然而，由于铁阳极消耗品的频繁更换，特别是电极结垢，其成本相对较高。在此，我们报告一种用于高效去除膦酸盐的废铁填充床（ISPB）阳极电凝（EC）系统。在NaSO、NaCl和NaHCO电解质中，ISPB-EC系统在库仑剂量为144 C/L时，能有效去除0.1 mM总可溶性磷（TSP）浓度下39%-99%的次氮基三甲基三膦酸（NTMP）。相比之下，在相同条件下，传统Fe-EC仅能去除2%-23%的NTMP。我们还发现NTMP部分转化为无机磷酸盐，这主要归因于ISPB-EC系统中Fe氧化过程中HO·和Fe(IV)O的形成。我们进一步验证了ISPB-EC在实际条件下（包括实际冷却水（ACW））的适应性和强大功效。我们的成本计算表明，新系统处理含NTMP的ACW的成本（0.0067欧元/立方米）低于传统Fe-EC系统（0.009欧元/立方米）。此外，我们解决了新开发的ISPB-EC系统中的结垢问题。在短期批量试验中，我们未注意到明显的阴极结垢。然而，在连续流实验中，阴极上逐渐形成橙红色水垢，同时电池电压升高。为此，我们提出并验证了周期性极性反转策略以减轻阴极结垢。值得注意的是，通过极性反转消除阴极污垢后，补充废铁可将电压降至初始水平，实现ISPB-EC系统超过336小时的长期稳定运行。我们的工作建立了一种使用廉价废铁电极处理含膦酸盐废水的经济高效的电凝系统。
