State Key Laboratory of Environmental Aquatic Chemistry, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing, 100085, People's Republic of China; University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China.
University of Chinese Academy of Sciences, Beijing, 100049, People's Republic of China.
Chemosphere. 2020 Jan;238:124632. doi: 10.1016/j.chemosphere.2019.124632. Epub 2019 Aug 23.
Fenton (Fe + HO) reagents acting to remove organic pollutants possess dual functions, including the oxidation by hydroxyl radicals and the coagulation of Fe(III). Previous papers have extensively studied the oxidation reactions by hydroxyl radicals, however, the coagulation role of Fenton for benzoic acid (BA) removal is not clear. Comparing three coagulation systems, it was found that Fenton coagulation possesses a significant advantage for the removal of BA. Through Fenton conditional experiments, results showed that with the increase of HO dosage, not only was the Fenton oxidation effect improved, but the Fenton coagulation effect was also significantly enhanced. Interestingly, the flocs produced by in situ Fenton possess a better coagulation effect than an aged Fenton system when processing BA. To further explain these results, Zeta potential, Transmission electron microscope (TEM), X-ray diffraction (XRD), X-ray absorption fine structure (EXAFS) and Brunner-Emmet-Teller (BET) measurements were used for characterization, and we found that the flocs produced by Fenton possessed a smaller particle size, lower polymerization states and a larger specific surface area and pore volume, which exposed more active sites to create a better coagulation effect. Additionally, through Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS) and Gas chromatography-mass spectrometer (GC-MS), we found that in situ Fenton oxidation and coagulation have synergistic effects, and the carboxyl-containing intermediates produced by the Fenton oxidation of BA can be combined with hydroxyl active sites of the flocs produced by in situ Fenton, resulting in a better removal effect. Finally, Fenton oxidation increases oxygen/carbon (O/C) to promote Fenton coagulation, and in situ Fenton more fully utilizes the active sites on the flocs' surface.
芬顿（Fe+HO）试剂在去除有机污染物时具有双重功能，包括羟基自由基的氧化作用和 Fe(III)的混凝作用。以前的论文已经广泛研究了羟基自由基的氧化反应，但芬顿试剂对苯甲酸（BA）去除的混凝作用尚不清楚。通过比较三种混凝体系，发现芬顿混凝在去除 BA 方面具有显著优势。通过芬顿条件实验，结果表明，随着 HO 用量的增加，不仅芬顿氧化效果得到改善，而且芬顿混凝效果也得到显著增强。有趣的是，在用原位芬顿处理 BA 时，原位芬顿产生的絮体具有比老化的芬顿体系更好的混凝效果。为了进一步解释这些结果，我们使用 Zeta 电位、透射电子显微镜（TEM）、X 射线衍射（XRD）、X 射线吸收精细结构（EXAFS）和 Brunner-Emmet-Teller（BET）测量进行了表征，发现芬顿产生的絮体具有更小的粒径、更低的聚合状态以及更大的比表面积和孔体积，这为其创造更好的混凝效果提供了更多的活性位点。此外，通过傅里叶变换红外光谱（FTIR）、X 射线光电子能谱（XPS）和气相色谱-质谱联用仪（GC-MS），我们发现原位芬顿氧化和混凝具有协同作用，BA 的芬顿氧化产生的含羧基中间体可以与原位芬顿产生的絮体的羟基活性位点结合，从而达到更好的去除效果。最后，芬顿氧化增加了氧/碳（O/C）比，促进了芬顿混凝，并且原位芬顿更充分地利用了絮体表面的活性位点。
