In-situ oxidative degradation of sulfamethoxazole by calcium peroxide/persulfate dual oxidant system in water and soil

Calcium peroxide (CaO₂) and persulfate (PS) dual oxidant system is an innovative in-situ chemical oxidation (ISCO) technique for the restoration of contaminated groundwater. Several field applications also confirm its efficacy in remediating the groundwater, however, published articles are rarely present. In this work, the performance of the CaO₂/PS system was examined for the degradation of sulfamethoxazole (SMX) in the SMX polluted soil and water. Results indicated that SMX could be efficiently degraded with CaO₂ and PS (2 g/L dosages for each oxidant) around neutral pH (7), and 95.8% pollutant removed after 36 h of reaction time. The removal efficiency of SMX improved as the concentrations of CaO₂ and PS were increased. Moreover, SMX removal was significantly decreased with the increase of initial solution pH. This dual oxidant system at 30 °C was also used for the remediation of SMX (10 mg/kg) spiked soil. Soil degradation experiment was performed at 150 rpm of shaking speed using soil slurry (soil/water; 1/1 ratio) at pH 7. Dual oxidant dosage was kept at 2 g/L CaO₂ and 2 g/L PS. The results showed that this dual oxidant system is also very efficient for the antibiotics SMX degradation in the soil system. Overall, an insight knowledge and practical information gained from this work will help in the treatment of SMX contaminated soil and water as well as wastewater with CaO₂/PS dual oxidant system.