Abstract：
Iron (hydr)oxides are abundant in surface environment, and actively participate in the transformation of organic pollutants due to their large specific surface areas and redox activity. This work investigated the transformation of tetracycline (TC) in the presence of three common iron (hydr)oxides, hematite (Hem), goethite (Goe), and ferrihydrite (Fh), under simulated sunlight irradiation. These iron (hydr)oxides exhibited photoactivity and facilitated the transformation of TC with the initial phototransformation rates decreasing in the order of: Hem > Fh > Goe. The linear correlation between TC removal efficiency and the yield of HO• suggests that HO• dominated TC transformation. The HO• was produced by UV-induced decomposition of self-generated H2O2 and surface Fe2+-triggered photo-Fenton reaction. The experimental results indicate that the generation of HO• was controlled by H2O2, while surface Fe2+ was in excess. Sunlight-driven H2O2 production in the presence of the highly crystalline Hem and Goe occurred through a one-step two-electron reduction pathway, while the process was contributed by both O2-induced Fe2+ oxidation and direct reduction of O2 by electrons on the conduction band in the presence of the poorly crystalline Fh. These findings demonstrate that sunlight may significantly accelerate the degradation of organic pollutants in the presence of iron (hydr)oxides.
摘要：
表面环境中氧化铁丰富，并由于其大的比表面积和氧化还原活性而积极参与有机污染物的转化。这项工作研究了在三种常见氧化铁（hydr）存在下四环素（TC）的转化，赤铁矿（Hem），针铁矿(Goe),和水铁矿(Fh)，在模拟阳光照射下。这些铁（氢）氧化物表现出光活性并促进TC的转化，初始光转化速率按以下顺序降低：Hem>Fh>Goe。TC去除效率与HO·产量之间的线性相关关系表明HO·主导了TC转化。HO•是通过紫外线诱导的自生成H2O2分解和表面Fe2触发的光-Fenton反应产生的。实验结果表明，HO•的产生受H2O2控制，而表面Fe2过量。在高度结晶的Hem和Goe存在下，阳光驱动的H2O2产生通过一步两电子还原途径发生，而该过程是由O2诱导的Fe2氧化和在晶体较差的Fh存在下导带上的电子直接还原O2引起的。这些发现表明，在存在铁（hydr）氧化物的情况下，阳光可能会显着加速有机污染物的降解。
