Kinetic and mechanistic investigation of water taste and odor compound 2-isopropyl-3-methoxy pyrazine degradation using UV-A/Chlorine process

Maria Antonopoulou; Nikolaos Ioannidis; Triantafyllos Kaloudis; Theodoros M Triantis; Anastasia Hiskia

doi:10.1016/j.scitotenv.2020.138404

Kinetic and mechanistic investigation of water taste and odor compound 2-isopropyl-3-methoxy pyrazine degradation using UV-A/Chlorine process

Sci Total Environ. 2020 Aug 25:732:138404. doi: 10.1016/j.scitotenv.2020.138404. Epub 2020 Apr 18.

Authors

Maria Antonopoulou¹, Nikolaos Ioannidis², Triantafyllos Kaloudis³, Theodoros M Triantis³, Anastasia Hiskia³

Affiliations

¹ Laboratory of Photo-Catalytic Processes and Environmental Chemistry, Institute of Nanoscience & Nanotechnology, NCSR "Demokritos", Patr. Gregoriou E & 27 Neapoleos Str, 15341 Agia Paraskevi, Athens, Greece. Electronic address: m.antonopoulou@inn.demokritos.gr.
² Laboratory of Molecular Magnetic and Bioinorganic Spectroscopy, Institute of Nanoscience & Nanotechnology, NCSR "Demokritos", Patr. Gregoriou E & 27 Neapoleos Str, 15341 Agia Paraskevi, Athens, Greece.
³ Laboratory of Photo-Catalytic Processes and Environmental Chemistry, Institute of Nanoscience & Nanotechnology, NCSR "Demokritos", Patr. Gregoriou E & 27 Neapoleos Str, 15341 Agia Paraskevi, Athens, Greece.

PMID: 32474265
DOI: 10.1016/j.scitotenv.2020.138404

Abstract

The present study was launched as a continuation of global efforts to tackle problems associated with two important aesthetic characteristics, taste and odor (T&O), of drinking water. The UV-A/Chlorine process, a promising advanced oxidation process (AOP), was evaluated for the first time for the removal of 2-isopropyl-3-methoxy pyrazine (IPMP), a widely reported compound in the literature that causes unpleasant taste and odor when present in water at or below the ng L^-1 level. It was found that the studied process was efficient for the removal of IPMP in both ultrapure and drinking water. The initial chlorine dosage influenced significantly the degradation efficiency under initial neutral pH values. Degradation efficiency of IPMP was slightly inhibited by using drinking water as matrix. Scavenging experiments highlighted the significant role of various reactive species (e.g. HO, ClO, Cl, Cl₂^-) generated during the process that have not been studied comprehensively until now. In addition, the significant role of HO was further verified by Electron paramagnetic resonance spectroscopy (EPR) experiments. Overall, the formation of diverse radicals during the UV-A/Chlorine treatment enhanced the degradation of IPMP, promoting mainly the formation of hydroxy, hydroperoxy and dealkylated derivatives. In contrast, chlorinated by-products were only identified in traces.

Keywords: Advanced oxidation process; EPR; Reactive species; Transformation products; UV-A/Chlorine; Water taste and odor.