In situ chemical oxidation of tinidazole in aqueous media by heat-activated persulfate: kinetics, thermodynamic, and mineralization studies

Abstract

AbstractThis study investigated the use of heat-activated persulfate (HAP) as a chemical oxidation technique for removing tinidazole (TNZ) antibiotic from aqueous solutions. The impact of various operating parameters, including TNZ initial concentration (20 μM), persulfate (PS) initial dose (0.2–2 mM), solution pH (3–11), solution temperature (20–60 °C), and reaction time (10–120 min), was examined. The results indicated that sulfate radicals were the primary species responsible for TNZ degradation. Higher temperatures and PS concentrations improved the process, while higher pH values and TNZ initial concentrations slowed it down. Additionally, chloride and bicarbonate ions reduced reaction rates, with chloride ions having a more significant effect. Under optimal conditions (including [TNZ]0 = 20 μM, pH = 7, [PS]0 = 1 mM, temperature = 60 °C, and reaction time = 120 min), the removal efficiency achieved was 91.15%, with a mineralization rate of 85.8%. These results suggest that the process is relatively safe. The degradation of TNZ was best described by the pseudo-first-order model compared to other models. Additionally, the process was found to be exothermic and spontaneous, with a negative Gibbs free energy change indicating that it is thermodynamically feasible. The study found HAP to be an effective and cost-efficient technique for removing TNZ antibiotic due to its ease of operation and the absence of the need for additional chemicals or waste handling. Based on these findings, HAP can be considered an advanced oxidation technique for treating antibiotic-contaminated water.