Kinetics and modeling of sulfonamide antibiotic degradation in wastewater and human urine by UV/H2O2 and UV/PDS

Sulfonamide antibiotics have been frequently detected in the aquatic environment and are of emerging concern due to their adverse bio-effect and potential of inducing antibiotic resistance. This study investigated the degradation kinetics of sulfonamide antibiotics in synthetic wastewater and hydrolyzed human urine by low pressure (LP) UV, UV/H2O2 and UV/peroxydisulfate (PDS). Direct photolysis rates of sulfonamide antibiotics varied and depended on the structures. Sulfonamides with a five-membered heterocyclic group underwent faster direct photolysis. For indirect photolysis processes, second-order rate constants of sulfonamide antibiotics with hydroxyl radical, sulfate radical and carbonate radical were determined, which were (6.21–9.26) × 109, (0.77–16.1) × 1010 and (1.25–8.71) × 108 M−1 s−1, respectively. A dynamic model was applied and successfully predicted the degradation kinetics of sulfonamides in different water matrices. In synthetic wastewater, carbonate radical contributed to approximately 10% of the overall removal, whereas in synthetic hydrolyzed urine, carbonate radical was the dominant reactive species to degrade sulfonamides. Sulfonamide antibiotics were eliminated more efficiently in synthetic hydrolyzed urine than in synthetic wastewater and UV/PDS was more efficient than UV/H2O2 to degrade most sulfonamides. Energy evaluation showed that UV/PDS costs less energy than LPUV and UV/H2O2 under the experimental conditions applied in this study, particularly for sulfonamides whose indirect photolysis overweighed direct photolysis. By varying UV dose and oxidant dose, the UV/H2O2 process can be optimized to achieve higher efficiency than the UV/PDS process in synthetic wastewater. [Display omitted] •Sulfonamides with five-membered heterocyclic group undergo rapid direct photolysis.•Reactivity of ·OH, SO4·− and CO3·− with sulfonamides are quantitatively determined.•Most of the investigated sulfonamides are degraded faster by UV/PDS than by UV/H2O2.•Sulfonamide degradation is mainly due to carbonate radical in hydrolyzed urine.•UV/H2O2 process is more energy-efficient than UV/PDS in synthetic wastewater.