Effects of dissolved organic matter and coordination with Cu(Ⅱ) on the phototransformation of sulfamethazine in aqueous solutions
LI YingJie;WEI XiaoXuan;QIAO XianLiang;CHEN JingWen;Key Laboratory of Industrial Ecology and Environmental Engineering(Ministry of Education),School of Environmental Science and Technology,Dalian University of Technology;
Sulfonamide antibiotics(SAs) are well-acknowledged micropollutants in the aquatic environment at concentrations as high as μg/L. SAs are of acute concern because they can trigger an increase of resistant bacteria and accelerate the development of antibiotic resistance genes. Phototransformation plays an important role in the degradation of antibiotics in surface waters,and influences the fate and ecological risks of antibiotics. The photochemical behavior of antibiotics was obviously impacted by water constituents. However,water constituents and their interactions with metal ions on antibiotics photodegradation are still unclear. In this study,sulfamethazine(SMZ) was selected as target compound due to its wide usage in aquaculture and livestock operations. The effects of dissolved organic matter(DOM) and its coordination with Cu(II) on SMZ photodegradation were investigated. Results show that excited triplet state DOM(3DOM*) is largely responsible for the photolytic enhancement of SMZ in the presence of DOM and the reaction mechanism is identified as electron transfer followed proton transfer from SMZ to 3DOM*. Additionally,the photogenerated ·OH was found in the Cu(II)-DOM system,which promoted the photodegradation of SMZ.