Application of UV-activated persulfate and peroxymonosulfate processes for the degradation of 1,2,3-trichlorobenzene in different water matrices

Abstract

© 2020, Springer-Verlag GmbH Germany, part of Springer Nature. The presence of a large number of micropollutants in the environment, including priority and emerging substances, poses a significant risk to surface and groundwater quality. Among them, trichlorobenzenes are widely used in the syntheses of dyes, pesticides, solvents, and other chemicals and have been identified as priority pollutants by the European Water Framework Directive. The main goal of this study was to investigate the behavior of 1,2,3-trichlorobenzene (TCB) during the sulfate radical–based advanced oxidation processes (SR-AOPs) involving UV activation of persulfate or peroxymonosulfate (UV/S2O82− and UV/HSO5− processes). For this purpose, TCB was subjected to SR-AOPs in synthetic water matrices containing humic acids or hydrogencarbonate and natural water samples and a comparative evaluation of the degradation process was made. The toxicity of the oxidation by-products was also assessed. The evaluation of TCB degradation kinetics results using principal component analysis indicates that the efficacy of the SR-AOPs was highly dependent on the pH, initial oxidant concentration, UV fluence, and matrix characteristics. In natural waters, TCB degradation by the UV/S2O82− process proved to be most effective in acidic conditions (pH 5), while the UV/HSO5− process showed the highest efficacy in basic conditions (pH 9.5), achieving a maximum TCB degradations of 97–99%. The obtained results indicate that UV/S2O82− and UV/HSO5− as new generation oxidation processes have significant potential for TCB removal from water and result in only minor toxicity after treatment (14–23% of Vibrio fischeri bioluminescence inhibition).