Reaction pathways and products risk assessment of sulfadiazine degradation by chlorine dioxide based on density functional theory and ECOSAR
Sulfadiazine(SD)is an artificial synthetic antibiotic occurring in various water environments,and its degradation and removal methods have become one of the hot topics worldwide.This study explored the reaction pathways and products of SD degradation by chlorine dioxide(ClO2)using a combination of density functional theory calculations and HPLC-MS/MS experimental analysis.Additionally,the acute toxicity and environmental risk levels of the reaction products were quantitatively predicted and evaluated based on ECOSAR.The results showed that the main reaction sites for SD degradation by ClO2 were the three double bonds and 3C-2N single bond of the pyrimidine ring,the C-N,C-S,and N-S single bonds of the sulfonamide group,and the aniline group.The reaction pathways included addition,hydroxylation,hydroxyl substitution,ring-opening and coupling reactions of the pyrimidine ring,rupture of the sulfonamide group,and oxidation reaction of the aniline group.A total of 11 reaction products were identified,out of which 6 showed no harm to the three aquatic organisms and posed no environmental risks.The products of S-65 and S-141 presented moderate to low risks to daphnid and green algae.In contrast,all other products exhibited lower risk levels compared to the parent compound.The combination of theoretical model calculation and experimental analysis used in this study is convenient and reliable,which can provide a certain theoretical basis for studying the degradation of other complex organic compounds by ClO2.
antibioticsulfadiazinedensity functional theorychlorine dioxide(ClO2)GaussianMultiwfnquantum chemistryFukui index
NETL
NSTL
万方数据
