Cobalt/Peracetic Acid: Advanced Oxidation of Aromatic Organic Compounds by Acetylperoxyl Radicals

Abstract

Peracetic acid (PAA) is increasingly used as an alternative disinfectant and its advanced oxidation processes (AOPs) could be useful for pollutant degradation. Co­(II) or Co­(III) can activate PAA to produce acetyloxyl (CH3C­(O)­O•) and acetylperoxyl (CH3C­(O)­OO•) radicals with little •OH radical formation, and Co­(II)/Co­(III) is cycled. For the first time, this study determined the reaction rates of PAA with Co­(II) (k PAA,Co(II) = 1.70 × 101 to 6.67 × 102 M–1·s–1) and Co­(III) (k PAA,Co(III) = 3.91 × 100 to 4.57 × 102 M–1·s–1) ions over the initial pH 3.0–8.2 and evaluated 30 different aromatic organic compounds for degradation by Co/PAA. In-depth investigation confirmed that CH3C­(O)­OO• is the key reactive species under Co/PAA for compound degradation. Assessing the structure–activity relationship between compounds’ molecular descriptors and pseudo-first-order degradation rate constants (k′PAA• in s–1) by Co/PAA showed the number of ring atoms, E HOMO, softness, and ionization potential to be the most influential, strongly suggesting the electron transfer mechanism from aromatic compounds to the acetylperoxyl radical. The radical production and compound degradation in Co/PAA are most efficient in the intermediate pH range and can be influenced by water matrix constituents of bicarbonate, phosphate, and humic acids. These results significantly improve the knowledge regarding the acetylperoxyl radical from PAA and will be useful for further development and applications of PAA-based AOPs.

Activation of Peracetic Acid with Lanthanum Cobaltite Perovskite for Sulfamethoxazole Degradation under a Neutral pH: The Contribution of Organic Radicals

“…PAA was first adsorbed on the surface of LaCoO 3 , and then activated by the Co on the B site of perovskite to generate organic radicals, e.g., CH 3 COO • , which could act as an oxidant for SMX degradation. Meanwhile, Co(II) was oxidized to Co(III) after PAA activation (Equation (7)) [ 31 , 49 , 50 ]. The decomposition of CH 3 COO • can generate CO 2 and CH 3 • , which could further react with oxygen to generate CH 3 OO • .…”

Degradation of Reactive Blue 19 (RB19) by a Green Process Based on Peroxymonocarbonate Oxidation System

“…is phenomenon can be explained by the great capability of Co 2+ in catalyzing oxidation reactions. In peroxyacid solutions, Co 2+ enhances the decomposition of peroxy compounds to generate radicals [14,15]. Applying the same mechanism, radicals are proposed to be formed by the following reactions:…”

Diketone and UV based advanced oxidation/reduction technologies: molecular mechanisms and research advances

“…张国洋等: 双酮基光化学高级氧化/还原技术：分子机制解析及研究进展 图 6 (a) 高级氧化/还原技术体系中相关的自由基以及氧化剂的还原电位天梯图(E 0 vs. NHE) [57] ; (b) UV/双酮体系中有机自由基(直接 裂解以及氧合、水合后的自由基)的理论氧化还原电位(E 0 vs. NHE), 计算方法引自文献 [58] (网络版彩图) Figure 6 (a) Redox ladder of redox couples (E 0 vs. NHE) in the advanced oxidation/reduction technology (AOTs) [57] ; (b) One electron standard reduction potential (E 0 vs. NHE) of the organic free radicals in UV/diketone system. The calculation method was cited from the literature [58] (color online) 值得一提的是, 虽然传统氧化剂(O3、H2O2、Cl2 [61] . Zhang 等利用 UV/BD 法降解四环素 时发现, N2 吹扫完全抑制了 UV/BD 法对四环素的降 解, 说明 CH3C(O)OO•参与的氧化是 BD 体系降解四环 素的主要机制 [24] .…”

“…尽管草酸铁的光活 性比乙酰丙酮铁和水杨酸铁高得多(三者在 254 nm 的 光化学量子产率分别为 1.25, 0.23 和 0.02), 草酸并不 具有维持 Fe(II)状态的能力, 而 Fe 在 UV/水杨酸体系 的转化速率较 UV/双酮体系慢得多(图 7a 和 7b) [19] . 四 种有机物(草酸、水杨酸、AA 以及 BD)还原 Fe(III)的 速率(图 7c)以及氧化 Fe(II)的速率(图 7d)均和体系耗 氧速率呈现明显的线性关系 [19] [61] .…”