Predicting combined antibacterial activity of sulfapyridine and its transformation products during sulfapyridine degradation

Antibiotics have strong antibacterial activity, even trace antibiotics can greatly inhibit the pollutant degradation efficiency. In order to effectively improve the pollutant degradation efficiency, it was hence of great significance to explore sulfapyridine (SPY) degradation and the mechanism of antibacterial activity. This study selected SPY as the research object, of which the trend of SPY concentration through hydrogen peroxide (H2O2), potassium peroxydisulfate (PDS) and sodium percarbonate (SPC) and resultant antibacterial activity at pre-oxidation was examined. The combined antibacterial activity (CAA) of SPY and its transformation products (TPs) was further analyzed. The SPY degradation efficiency reached more than 90 %. However, the degradation efficiency of antibacterial activity was between 40-60 %, and the mixture's antibacterial activity was difficult to be removed. The antibacterial activity of TP3, TP6 and TP7 was higher than that of SPY. TP1, and TP8 and TP10 were more prone to synergistic reaction with other TPs. The antibacterial activity of binary mixture gradually changed from synergism to antagonism as binary mixture concentration increased. The results provided a theoretical basis for the efficient degradation of antibacterial activity of the SPY mixture solution.