Abstract In this work, the removal of the non-readily biodegradable herbicide clopyralid by electrochemical (EC) and photoelectrochemical (PhEC) oxidation with different anode materials were conducted looking to improve not only its oxidation but also its biodegradability. First, in order to find out optimal conditions, it was carried out EC and PhEC degradations in chloride medium, at current densities ranging from 30 to 100 mA cm−2 during 1 h (0.8–2.7 A h L−1), using as anodes MMO-RuO2TiO2, MMO-RuO2IrO2, MMO-IrO2Ta2O5 and boron-doped diamond (BDD). Results show better efficiencies on clopyralid removal for MMO-RuO2IrO2 and BDD anodes at lower current densities. Then, the influence of all anodes on clopyralid transformation was evaluated, extending the electrolysis and photoelectrolysis for 8 h applying 30 mA cm−2 (6.4 A h cm−3). At these conditions, better outcomes are observed for PhEC degradation, where complete pollutant removal is attained for BDD anode and 88.7% for MMO-RuO2IrO2, while COD removal is 47.7% for MMO and 43.1% for BDD anode. Then, short-term biodegradability tests, conducted for EC and PhEC processes, pointed out that MMO-RuO2TiO2 is the most promising anode material, being capable of improving biodegradability in 48.2% and 53% for EC and PhEC degradation, respectively. The toxicity of treated solutions using MMO-RuO2TiO2 and BDD anodes in both EC and PhEC degradation were compared, employing the inhibitory effect in the bioluminescence of marine bacteria Vibrio Fisheri. Toxicity assessments show that toxicity significantly reduces by using the MMO-RuO2TiO2 in NaCl and Na2SO4 medium for both processes. Finally, this study demonstrates that photoelectrolysis with MMO anodes was the most effective strategy in order to increase biodegradability in chloride media, as well as to reduce the toxicity of the treated waste.

中文翻译：

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通过光电解提高氯吡咯酸废物的生物降解性：阳极材料的作用

摘要 在这项工作中，通过电化学 (EC) 和光电化学 (PhEC) 氧化与不同的阳极材料进行去除不易生物降解的除草剂氯吡菌胺，以期不仅改善其氧化性，还改善其生物降解性。首先，为了找出最佳条件，在氯化物介质中进行 EC 和 PhEC 降解，电流密度范围为 30 到 100 mA cm-2，在 1 小时内（0.8-2.7 A h L-1），使用作为阳极 MMO-RuO2TiO2、MMO-RuO2IrO2、MMO-IrO2Ta2O5 和掺硼金刚石 (BDD)。结果表明，在较低的电流密度下，MMO-RuO2IrO2 和 BDD 阳极的氯吡咯烷去除效率更高。然后，评估所有阳极对氯吡菌胺转化的影响，应用 30 mA cm-2 (6.4 A h cm-3) 将电解和光电解延长 8 小时。在这些条件下，PhEC 降解得到更好的结果，其中 BDD 阳极实现了完全污染物去除，MMO-RuO2IrO2 实现了 88.7%，而 MMO 和 BDD 阳极的 COD 去除率为 47.7% 和 43.1%。然后，针对 EC 和 PhEC 工艺进行的短期生物降解性测试指出，MMO-RuO2TiO2 是最有前途的负极材料，能够将 EC 和 PhEC 降解的生物降解性分别提高 48.2% 和 53%。使用 MMO-RuO2TiO2 和 BDD 阳极处理的溶液在 EC 和 PhEC 降解中的毒性进行了比较，利用海洋细菌 Vibrio Fisheri 生物发光的抑制作用。毒性评估表明，对于这两种工艺，在 NaCl 和 Na2SO4 介质中使用 MMO-RuO2TiO2 可显着降低毒性。最后，