Degradation of prometryn during UV/persulfate process: Kinetics and disinfection by-product formation

Abstract

Prometryn is one of the commonly used triazine herbicides and is also widely used for algae removal in aquaculture. This study investigated the degradation kinetics of prometryn via UV/persulfate (PS) oxidation and confirmed its adherence to pseudo-first-order kinetics, with a calculated rate constant (kobs) of 0.2358 min−1. The impact of PS concentration, water matrix (including background ions of Cl− and Br− and natural organic matter (NOM)), and solution pH on prometryn degradation were assessed. Results indicated an increase in prometryn degradation with raising concentrations of PS, Cl−, and Br−, especially evident at a PS concentration of 400 μm where complete degradation was achieved. Conversely, degradation decreased with increasing NOM concentration and pH. Radical scavenging experiments affirmed the promotion of prometryn degradation in UV/PS by both HO• and SO4−•, with SO4−• contributing over 70 % of the total free radical contribution. Evaluation of disinfection by-product (DBP) formation revealed trichloromethane (TCM) as the predominant DBP in non‑bromine water and tribromomethane (TBM) in bromine water. Thus, this study offers a theoretical foundation for UV/PS degradation of triazine herbicides in aqueous environments. The obtained results hold significance for controlling DBPs in subsequent water treatment processes, ensuring the provision of safe drinking water to the public and meeting the sustainable development goal 6.