UV-assisted chemical oxidation of antihypertensive losartan in water

Population growth and deteriorating health issues have led to an increase in the consumption of angiotensin receptor blockers (ARBs), such as losartan (LOR), for treating high blood pressure and, as a result, to the frequent detection of these drugs in water and wastewater. The present study focuses on the oxidation of LOR by UV photolysis, UV(/Fe²⁺)-activated persulfate (PS) and hydrogen peroxide (H₂O₂) systems. The effects of operating parameters including pH value, reaction time, concentration of oxidant and activator on the efficacy of treatment were studied. The target compound degradation by direct UV photolysis, UV/PS and UV/H₂O₂ systems proved to be efficient and followed a pseudo-first-order kinetic model. The application of UV/oxidant systems even at lower PS or H₂O₂ concentrations resulted in more than 95% of LOR degradation in 10 min. In addition, the use of UV/Fe²⁺-activated oxidant systems led to a further increase in the k_obs by improving the LOR oxidation in aqueous solution. The effectiveness of LOR mineralization based on total organic carbon (TOC) removal was also considered. The optimized results of the studied systems obtained in ultrapure water were used in groundwater to assess the effectiveness of LOR decomposition in more complex environmental matrix. Moreover, the acute toxicity of LOR solutions before and after the UV/Fe²⁺-activated PS and H₂O₂ oxidation to luminous bacteria (Vibrio fischeri) was investigated.