Degradation of geosmin and 2-methylisoborneol in water with UV/chlorine: Influencing factors, reactive species, and possible pathways. (November 2018)

• Record Type: Journal Article
• Authors: Ma, Lingfei; Wang, Chaoyi; Li, Haipu; Peng, Fangyuan; Yang, Zhaoguang
• Is Part Of: Chemosphere. Volume 211(2018)
• Page Start: 1166
• Page End: 1175
• Publication Date: 2018-11
• Subjects: Odor compound -- Removal -- Active radical -- Degradation byproducts; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2018.08.029
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Geosmin (GSM) and 2-methylisoborneol (2-MIB) are two common odor compounds in drinking water. In this paper, the performance of UV/chlorine was compared with that of chlorine and UV to degrade GSM (100 ng L −1 ) and 2-MIB (100 ng L −1 ) in water. UV/chlorine was further exploited, and a steady-state kinetic model was used to conduct a detailed study on efficiency, rate, reactive species and pathway. The results showed that UV/chlorine greatly could improve the removal ratio to 90% within 5 min, from approximately 20% with only UV or dark chlorine in 60 min. The removal ratio and rate depended on UV light intensity, free chlorine dosage, reaction time and water quality parameters (e.g. pH, concentrations of HCO3 − and Cl − ). Among these factors, the first two obviously could accelerate the rate and increase the ratio. The degradation was also significantly improved in an acidic condition, while alkaline conditions and HCO3 − had inhibitory effects, and Cl − created no difference. Contributions of OH and Cl to the degradation of 2-MIB and GSM were further revealed, and OH was found to be the most important reactive species. In the UV/chlorine process, 6 degradation byproducts of 2-MIB, including 1 alcohol, 2 ketones, and 3 olefins, were identified, and 14 degradation byproducts of GSM, including 6 ketones, 1 aldehyde, 2 alcohols, 3 naphthenes, and 2 olefins, were found by using solid-phase microextraction coupled to gas chromatography-mass spectrometry. The possible degradation pathways of GSM and 2-MIB in UV/chlorine thus were proposed. Graphical abstract: Image 1 Highlights: Influencing factors in degrading 2-MIB and GSM with UV/chlorine were evaluated. The contributions ofCl andOH for degradation were investigated. Six and 14 degradation by-products of 2-MIB and GSM were identified, respectively. The degradation pathways of 2-MIB and GSM in UV/chlorine were proposed.