Sunlight-Induced Interfacial Electron Transfer of Ferrihydrite under Oxic Conditions: Mineral Transformation and Redox Active Species Production.
Sunlight-Induced Interfacial Electron Transfer of Ferrihydrite under Oxic Conditions: Mineral Transformation and Redox Active Species Production.
复制标题
氧化条件下阳光诱导水合铁的界面电子转移：矿物转化和氧化还原活性物质的产生。
DOI：
10.1021/acs.est.2c04594
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发表时间：
2022-09
影响因子：
11.4
通讯作者：
Zhipeng Shu;Z. Pan;Xingxing Wang;Haohua He;Shuwen Yan;Xiuping Zhu;Weihua Song;Zimeng Wang
中科院分区：
文献类型：
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作者：
Zhipeng Shu;Z. Pan;Xingxing Wang;Haohua He;Shuwen Yan;Xiuping Zhu;Weihua Song;Zimeng Wang
铁（II）催化的缺氧条件下的水铁矿转化已被深入研究，而这样的机制是不足以被应用在好氧环境与贫Fe（II）。在这里，我们研究了在溶解氧的存在下，在没有初始添加溶解的Fe（II）的情况下，阳光驱动的水铁矿转化的扩展途径。我们发现，阳光下显着促进水铁矿转化为针铁矿相比，在黑暗条件下。氧化还原活性物种（空穴-电子对，活性自由基，和Fe（II））产生的水铁矿界面通过光诱导电子转移过程。系统地改变湿化学条件的实验探索了三种途径对产生羟基自由基的相对贡献：（1）水的氧化（5.0%）;（2）溶解氧的还原（40.9%）;和（3）Fe（III）-羟基络合物的光解（54.1%）。结果还表明，在酸性条件下，超氧自由基作为Fe（II）再氧化的主要氧化剂，从而促进了水铁矿的转化。无机离子（氯化物、硫酸盐和硝酸盐）的存在不仅会影响Fe（III）的水解和沉淀，还会影响通过光致电荷转移反应产生自由基。氧化还原活性物种的参与和伴随的矿物转化将对水环境中多价元素和有机污染物的归宿产生深远的影响。
Fe(II)-catalyzed ferrihydrite transformation under anoxic conditions has been intensively studied, while such mechanisms are insufficient to be applied in oxic environments with depleted Fe(II). Here, we investigated expanded pathways of sunlight-driven ferrihydrite transformation in the presence of dissolved oxygen, without initial addition of dissolved Fe(II). We found that sunlight significantly facilitated the transformation of ferrihydrite to goethite compared to that under dark conditions. Redox active species (hole-electron pairs, reactive radicals, and Fe(II)) were produced from the ferrihydrite interface via the photoinduced electron transfer processes. Experiments with systematically varied wet chemistry conditions probed the relative contributions of three pathways for the production of hydroxyl radicals: (1) oxidation of water (5.0%); (2) reduction of dissolved oxygen (40.9%); and (3) photolysis of Fe(III)-hydroxyl complexes (54.1%). Results also showed superoxide radicals as the main oxidant for Fe(II) reoxidation under acidic conditions, thus promoting the ferrihydrite transformation. The presence of inorganic ions (chloride, sulfate, and nitrate) did not only affect the hydrolysis and precipitation of Fe(III) but also the generation of radicals via photoinduced charge transfer reactions. The involvement of redox active species and the accompanying mineral transformations would exert a profound effect on the fate of multivalent elements and organic contaminants in aquatic environments.