Effect and simulation of CO3·− on the degradation kinetics of sulfamethazine in UV/TiO2 system

• • Presence of HCO3−/CO3^2− (38–575 mg/L) increased SMR degradation rate by 6-fold in UV/TiO2 system, indicating significant rate enhancement in carbonate-rich wastewaters. • • Radical quenching experiments confirmed CO3·− as the dominant reactive species, with ·OH contributing secondarily; this mechanistic insight is crucial for optimizing treatment conditions. • • Kintecus-based kinetic model accurately predicted SMR degradation over time (R^2 not specified but stated as good), enabling prediction of radical contributions in real wastewater matrices. • • Model simulations revealed that CO3·− is the primary active species in actual wastewater, underscoring the need to consider carbonate radicals in designing AOPs for pharmaceutical removal.