Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China.
Faculty of Environmental Science and Engineering, Kunming University of Science and Technology, Kunming 650500, China; Environmental Engineering and Science Program, Department of Chemical and Environmental Engineering (ChEE), 705 Engineering Research Center, University of Cincinnati, Cincinnati, OH, 45221-0012 USA.
Water Res. 2021 Feb 15;190:116740. doi: 10.1016/j.watres.2020.116740. Epub 2020 Dec 9.
Humic acids (HA) are common mediators in redox reactions in the aquatic environment. The structures and properties of HA are greatly influenced by environmental factors such as external electrons. In this study, qualitative changes in electron-modified HA and the underlying mechanisms were reported, which not only contribute to understanding the fate of HA and their impact on organic pollutants, but could facilitate their potential use for water purification. The photochemical activity and electron-donating capacity of HA were improved due to the increase of phenolic and carboxyl components via the reduction modification by electrons, creating a novel and efficient photo-bio-electro-Fenton system mediated by HA under neutral conditions without the use of hydrogen peroxide (HO). The in-situ continuous production of HO ensured an adequate supply of hydroxyl radicals in this coupled system, achieving mineralization (92%) of HA and 17α-ethinylestradiol (EE2), a common synthetic estrogen with high estrogenic potency. Two degradation pathways with five degradation intermediates of EE2 were identified in our study. Effluents from the coupled system showed decreased endocrine-disrupting activity. Our findings demonstrated a new approach for the in-situ modification and potential use of HA for water treatment and particularly the concurrent degradation of HA and organic pollutants through a photo-bioelectrochemical system mediated by HA.
腐殖酸（HA）是水生环境中氧化还原反应的常见介质。HA 的结构和性质受外部电子等环境因素的影响很大。本研究报道了电子修饰 HA 的定性变化及其潜在机制，这不仅有助于理解 HA 的命运及其对有机污染物的影响，还可能促进其在水净化方面的潜在应用。通过电子还原修饰，HA 的光化学活性和供电子能力得到提高，增加了酚类和羧基成分，在中性条件下无需使用过氧化氢（HO）形成了一种新型、高效的光生物电化学-Fenton 体系，由 HA 介导。在该耦合体系中，原位连续产生 HO 确保了羟基自由基的充足供应，实现了 HA 和 17α-乙炔基雌二醇（EE2）的矿化（92%），EE2 是一种具有高雌激素活性的常用合成雌激素。在本研究中，确定了 EE2 的两种降解途径和五个降解中间体。耦合系统的流出物显示出降低的内分泌干扰活性。本研究结果为 HA 的原位修饰和潜在应用提供了一种新方法，通过 HA 介导的光生物电化学系统同时降解 HA 和有机污染物。
