Mechanism and process of sulfamethoxazole decomposition with persulfate activated by pulse dielectric barrier discharge plasma

•SMZ removal efficiency could improve from 73.0% to 87.2% with PS addition in pulse DBD system.•Imput power, pulse frequency, solution pH and liquid flow rate affect SMZ degrdation.•OH, e-, 1O2, ·O2– and ·SO- 4 participated in SMZ decomposition.•The decline of O3 and enhancement of ·OH and H2O2 were found after PS addition.•The overall toxicity was effectively weakened by pulse DBD plasma with PS treatment. The present study focused on pulse dielectric barrier discharge (DBD) plasma activated persulfate (PS) for sulfamethoxazole (SMZ) degradation in water. The results showed that PS addition could enhance removal efficiency of SMZ in pulse DBD plasma system. The highest removal efficiency, kinetic constant and energy efficiency reached 93.4%, 0.084 min−1 and 0.353 g/kWh respectively with the PS dosage of 40:1 and input power of 85 W. With increase of imput power and pulse frequency, the removal efficiency of SMZ was also increased. The removal efficiency was firstly enhanced and then declined as raising duty cycle and liquid flow rate. SMZ degradation was promoted in alkaline solution conditions. Active species including ·OH, e-, ·O2–, 1O2 and ·SO- 4 play a certain role in the degradation of SMZ. The decline of O3 and enhancement of ·OH and H2O2 were found after PS addition. In process of SMZ degradation, the overall conductivity increased but pH decreased. PS addition accelerated the removal of COD and TOC. The degradation process was explored by UV–Vis spectra, three-dimensional fluorescence and LC-MS. Three degradation pathways were deduced based on the indentified intermediates. SMZ degradation in the system was considered as a toxicity-attenuation process. The water matrix including Cl-, HCO3–, SO42- and HA have some impact on SMZ degradation. This study presented that pulse DBD plasma could activate PS efficiently, which finally improved pollutant removal efficiency and energy utilization.