Comparative evaluation of MSW incineration leachate treatment by heterogeneous catalytic O3 and UV/O3: The unexpected contribution of high salinity and overlooked role of excited state. (November 2022)

• Record Type: Journal Article
• Authors: Zhao, Zhiwei; Gan, Pengfei; Zhu, Chengjun; Li, Yunyi; Liu, Wen; Tong, Meiping; Ye, Jiangyu; Liang, Jialiang
• Is Part Of: Chemosphere. Volume 307:Part 4(2022)
• Publication Date: 2022-11
• Subjects: Municipal solid waste -- Incineration leachate -- Ozone -- Hypersaline wastewater -- Excited state; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2022.136143
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: The efficiency and mechanism of heterogeneous catalytic O3 and UV/O3 for municipal solid waste (MSW) incineration leachate advanced treatment was systematically compared. Prior to comparison, catalyst used in heterogenous catalytic O3 and operation parameters for each technology were optimized. The COD removal of CuO@Al2 O3 /O3 under its optimal parameters was 57.2%, which failed to meet the standard (≥75%). In contrast, the COD removal by UV/O3 could be 82.3%. The superior efficiency of UV/O3 over CuO@Al2 O3 /O3 could be summarized into three aspects: (I) Cu bounded ·OH (≡Cu–O·) preferentially attacked hydrophilic groups, while free hydroxyl radical (·OH) was non-selective, thus UV/O3 exhibited a unique three-stage mechanism; (II) The oxidation potential of ≡Cu–O· was higher than that of ·OH, therefore was more vulnerable to the negative effect of radical self-quenching; (III) The existence of UV-induced excited states made organics in UV/O3 more active than in CuO@Al2 O3 /O3 system, thus high concentration of anions enhanced COD removal in UV/O3 but affected that in CuO@Al2 O3 /O3 . The study further revealed the characteristics of heterogeneous catalytic O3 and UV/O3, and UV induced excited state should be considered in UV-based advanced oxidation processes (AOPs). Graphical abstract: Image 1 Highlights: UV/O3 was more efficient than CuO@Al2 O3 /O3 for MSW incineration leachate treatment. CuO@Al2 O3 /O3 had stronger mineralization effect but suffered the problem of self-quenching. UV induced excited state explained the absence of self-quenching in UV/O3 . O3, ≡Cu–O·, ·OH had different selectivity, and UV/O3 exhibited a unique three-stage mechanism. High salinity enhanced the mineralization ability of UV/O3 due to the presence of UV induced excited state.