Removal of hydrochlorothiazide from drinking and environmental water: Hydrolysis, direct and indirect photolysis

Diuretic hydrochlorothiazide (HCTZ) has been detected in drinking and environmental water. Since HCTZ exhibited some toxic effects on the environment, it is essential to propose safe and economical ways of its removal. The influence of water quality on the removal efficiency of HCTZ from the environment was observed. The stability of HCTZ was investigated in ultrapure (UPW), tap, and two different environmental waters, by hydrolysis, photolysis, and indirect photolysis under simulated solar irradiation (SSI) and UV irradiation. Also, experiments were conducted at temperatures of (5  ±  1) °C and (25  ±  1) °C, in the dark. Comprehensive experimental and computational analysis was performed to examine the stability and reactivity. The results show that HCTZ is susceptible to hydrolysis. Photolysis and indirect photolysis were efficient under UV irradiation, wherein HCTZ was entirely degraded after 180 min of irradiation in UPW. Chloride ions, carbonates, calcium, and magnesium ions present in natural waters inhibited the degradation of HCTZ. This diuretic has significant interaction with ^•OH radicals. A 4-amino-6-chlorobenzene-1,3- disulfonamide (ABSA) was observed as a stable degradation product, and ABSA formation's degradation mechanism was proposed. Mineralization of HCTZ was above 50% in H₂O₂/UV system in UPW after 180 min of irradiation.