Degradation of chloroaniline in chemical wastewater by ionizing radiation technology: Degradation mechanism and toxicity evaluation. (January 2022)

• Record Type: Journal Article
• Authors: Wang, Shizong; Wang, Jianlong
• Is Part Of: Chemosphere. Volume 287:Part 4(2022)
• Publication Date: 2022-01
• Subjects: Radiation -- Chloroaniline -- Degradation products -- Chemical wastewater -- Toxicity; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2021.132365
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Chloroaniline is a typical organic pollutant in chemical wastewater, which cannot be effectively removed in conventional wastewater treatment processes. In this study, ionizing radiation was used as advanced treatment process to degrade 2-chloroaniline (2-CA). The results showed that 10 mg/l of 2-CA could be completely degraded at 1 kGy. The required dose for completely degrading 2-CA by radiation increased when its initial concentration increased. Solution pH affected 2-CA degradation by changing the radiation-chemical yield of reactive species. Chloride ions (10 and 100 mM) had not obvious influence on 2-CA degradation. Hydrogen radicals, hydrated electrons and hydroxyl radicals, all contributed to the degradation of 2-CA, but with different degradation mechanisms. Hydrogen radicals and hydrated electrons could initiate reductive dechlorination of 2-CA, while hydroxyl radicals can degrade 2-CA by hydroxylation. 6-amino-1, 4-cyclohexadiene and chlorobenzene were the main intermediate products of 2-CA degradation in the hydrogen radicals or hydrated electrons dominant process; while o-hydroxyaniline and nitroso-chlorobenzene were the main intermediate products in the hydroxyl radicals dominant process. The solution toxicity after radiation treatment varied with the initial concentration of 2-CA and the absorbed dose. In the actual chemical wastewater, 2-CA can be effectively removed by radiation, even in the presence of high concentration of chloride ions (about 2800 mg/l). The solution toxicity of actual wastewater decreased with the increase of adsorbed dose. This study provided an insight into the 2-CA degradation by radiation, and demonstrated that radiation could be an alternative option for the treatment of chloroaniline-containing chemical wastewater. Graphical abstract: Image 1 Highlights: Three active species, including eaq −, HO. and H contributed to 2-CA degradation. Intermediate products of 2-CA degradation by different active species were analyzed. Toxicity of irradiated 2-CA solution varied with 2-CA concentration and dose. Ionizing radiation could effectively degrade 2-CA in wastewater.