Iron oxychloride (FeOCl) has been reported to be a highly efficient heterogeneous Fenton catalyst over a wide pH range. In order to determine the true catalytic performance of FeOCl, we simultaneously quantified the adsorptive and oxidative removal of formate, oxalate, and rhodamine-B (RhB) and the formation of RhB oxidation products at both pH 4.0 and 7.0. FeOCl was found to be a poor Fenton catalyst at either pH, as gauged by the oxidation of formate, oxalate, and rhodamine B and the decomposition of H₂O₂, in comparison with ferrihydrite (Fhy), one of the most common Fe-containing Fenton catalysts. The adsorption of target contaminants to FeOCl and homogeneous Fenton processes, induced by dissolved iron, resulted in overevaluation of the catalytic performance of FeOCl, especially for (i) the use of strongly adsorbing target compounds, without consideration of the role of adsorption in their removal and (ii) exceedingly high concentrations of H₂O₂ to remove trace quantities of target contaminants. Overall, this study highlights that the systematic quantification of H₂O₂ decomposition, target compound adsorption, and oxidation as well as the concentrations of oxidized products formed are prerequisites for unequivocal elucidation of the catalytic nature and reaction mechanism of solid Fenton catalysts.

中文翻译：

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评估新型芬顿催化剂时的关键考虑因素：三氯氧化铁 (FeOCl) 作为案例研究

据报道，氧氯化铁 (FeOCl) 是一种高效的非均相芬顿催化剂，可在很宽的 pH 范围内使用。为了确定 FeOCl 的真实催化性能，我们同时量化了甲酸、草酸和罗丹明-B (RhB) 的吸附和氧化去除，以及在 pH 4.0 和 7.0 下形成的 RhB 氧化产物。通过甲酸盐、草酸盐和罗丹明 B 的氧化和 H ₂ O ₂的分解来衡量，在任一 pH 值下，FeOCl 都被发现是不良的芬顿催化剂，与最常见的含铁芬顿催化剂之一的水铁矿（Fhy）相比。目标污染物吸附到 FeOCl 和由溶解的铁诱导的均相 Fenton 过程，导致对 FeOCl 的催化性能的高估，特别是对于 (i) 使用强吸附目标化合物，而不考虑吸附在其去除中的作用(ii) 极高浓度的 H ₂ O ₂以去除痕量的目标污染物。总的来说，这项研究强调了 H ₂ O ₂的系统量化 分解、目标化合物吸附和氧化以及形成的氧化产物的浓度是明确阐明固体芬顿催化剂的催化性质和反应机理的先决条件。