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132. The degradation of ciprofloxacin in the UV/NH2Cl process: kinetics, mechanism, pathways and DBP formationElectronic supplementary information (ESI) available. See DOI: https://doi.org/10.1039/d3ew00166k

Author

Zhang, Ruihua, Peng, Cheng, Wang, Qiongfang, Zou, Xinyu, Zhao, Qiming, Wang, Jiajun, Zhang, Jiayu, Dong, Lei, Zhang, Xin, and Gao, Naiyun

Abstract

In this work, UV/NH2Cl was utilized to remove ciprofloxacin (CIP) from water and the formation of disinfection by-products (DBPs) following disinfection was investigated to determine its applicability and safety. It was demonstrated that the degradation of CIP in UV/NH2Cl was significantly more effective than that in NH2Cl oxidation alone or UV alone. The presence of NOM (0–8 mg L−1), CO32−(0–8 mM), and NO3−(0–8 mM) inhibited CIP degradation with kobs,CIPfrom 0.030 to 0.012, 0.017, and 0.020 min−1, respectively. In contrast, the NH2Cl concentration (0.25–2 mM) and Cl−(0–8 mM) promoted the degradation of CIP with kobs,CIPincreasing from 0.022–0.054 min−1and 0.030–0.034 min−1. HCO3−had dual effects on the degradation of CIP. pH slightly affected the degradation of CIP by UV/NH2Cl in near neutral pH range but greatly inhibited it under strong acidic and alkaline conditions. The reaction rate constant of CIP and HO was calculated to be kHO,CIP= 3.0 × 109M−1s−1and the contribution of the reactive chlorine species and reactive nitrogen species to CIP degradation was much greater than that of HO. Intermediate products of CIP were identified and analyzed to propose 3 possible degradation pathways. The formation of DBPs with NH2Cl disinfection was lower than that with NaClO disinfection after the oxidation of UV/NH2Cl. Briefly, this study provides much useful information for a better understanding of the UV/NH2Cl process for water treatment.

Published
2023
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135. Evaluation of Fe 2+ /Peracetic Acid to Degrade Three Typical Refractory Pollutants of Textile Wastewater.

Author

Yu, Jiali, Shu, Shihu, Wang, Qiongfang, Gao, Naiyun, and Zhu, Yanping

Subjects
POLLUTANTS, SEWAGE, WASTEWATER treatment, HUMIC acid, REFRACTORY materials
Abstract

In this work, the degradation performance of Fe2+/PAA/H2O2 on three typical pollutants (reactive black 5, ANL, and PVA) in textile wastewater was investigated in comparison with Fe2+/H2O2. Therein, Fe2+/PAA/H2O2 had a high removal on RB5 (99%) mainly owing to the contribution of peroxyl radicals and/or Fe(IV). Fe2+/H2O2 showed a relatively high removal on PVA (28%) mainly resulting from ·OH. Fe2+/PAA/H2O2 and Fe2+/H2O2 showed comparative removals on ANL. Additionally, Fe2+/PAA/H2O2 was more sensitive to pH than Fe2+/H2O2. The coexisting anions (20–2000 mg/L) showed inhibition on their removals and followed an order of HCO3− > SO42− > Cl−. Humic acid (5 and 10 mg C/L) posed notable inhibition on their removals following an order of reactive black 5 (RB5) > ANL > PVA. In practical wastewater effluent, PVA removal was dramatically inhibited by 88%. Bioluminescent bacteria test results suggested that the toxicity of Fe2+/PAA/H2O2 treated systems was lower than that of Fe2+/H2O2. RB5 degradation had three possible pathways with the proposed mechanisms of hydroxylation, dehydrogenation, and demethylation. The results may favor the performance evaluation of Fe2+/PAA/H2O2 in the advanced treatment of textile wastewater. [ABSTRACT FROM AUTHOR]

Published
2022
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