Study Of Sulfadiazine And Tetracycline Degradation In Aqueous Solution By Gamma Irradiation And Ultrasonic Cavitation

Sulfadiazine (SD) and tetracycline (TC) have been widely used in the treatment and prevention of a variety of animal diseases, which also can promote animal growth. But the abuse of SD and TC has led to its accumulation and residue in animals which can cause allergic reactions and flora. In addiation, it has also brought about the growing pathogens resistant strains of the human body. Therefore, it is necessary to develop efficient, and cheap and new treatment techniques because the conventional biological treatment method is difficult to achieve the desired efficiencies for the residual antibiotics in the wastewater.In this study, we selected sulfadiazine and tetracycline as target compounds to study. SD and TC degradation under gamma irradiation and ultrasonic cavitation. At the same time, we introduced quantum chemistry calculation theory using the Gaussian software to optimize the geometric structure of the SD and TC, which is based on density functional theory (DFT) B3LYP/6-31G(d) level. The purpose is to extrapolate mechanism of SD and TC removals on the basis of the calculated charge distribution, which can be verified by experimental results. The main contents are as follows:(1) With the studying of gamma irradiation induced SD degradation in an aqueous solution. We can get that SD can be effectively degraded by gamma irradiation in an aqueous solution. The degradation efficiencies of low-concentration SD can be remarkably improved in an acid solution. The degradation of SD was in accordance with the pseudo-first-order kinetic model. In addition, H2O2can gently promote degradation of SD induced by gamma radiation. Fenton reagent can markedly promote degradation of SD induced by gamma irradiation. However, SD removal was restrained with the addition of Na2CO3. Adding CH3OH in solution, we found that SD removal was restrained at low-irradiation dose while markedly promoted at high-irradiation dose. Based on the results of quantum chemical calculations and LC-MS analysis, SD degradation using gamma irradiation in aqueous solution is mainly ascribed to-OH oxidation and the direct decomposition of SD molecules.(2) The systematic study of the ultrasonic degradation of SD, and the results show that low-concentration SD can be effectively removed by ultrasonic in aqueous solution, the removal efficiencies can be remarkably enhanced in acidic solution, and the degradation of SD was in accordance with the pseudo-second-order kinetic model. In addition, H2O2and TiO2can promote ultrasonic induced degradation of SD to a certain extent. Then, SD removal can be markedly improved with the addition of Fenton reagent. Adding CH3OH in solution, we found that SD removal was markedly restrained. The degradation mechanism of SD was supposed by results of quantum chemical calculations and LC-MS. Ultrasonic induced degradation of SD is mainly ascribed to OH oxidation and the direct decomposition of SD molecules.(3) The result of gamma irradiation induced TC degradation in an aqueous solution show that TC can be effectively degraded by gamma irradiation in an aqueous solution. Degradation of TC can be remarkably improved both in acid solution and alkaline solution. In addition, H2O2and Na;CO3can gently promote degradation of TC induced by y-radiation. TC removal can be markedly improved with the addition of Fenton reagent. CH3OH can markedly restrained degradation of TC induced by y-radiation. The degradation mechanism of TC was investigated by results of quantum chemical calculations and LC-MS. Degradation of TC induced by y-radiation is mainly ascribed to OH radicals attack on TC molecules.(4) US induced TC degradation in an aqueous solution was also researched, and we found that low-concentration TC can be effectively removed by ultrasonic irradiation in aqueous solution. The presence of OH-can remarkably enhance TC removal efficiencies. In addition, H2O2and Na2CO3can promote ultrasonic induced degradation of TC to a certain extent. TC removal can be markedly improved with the addition of Fenton reagent. CH3OH can markedly restrained degradation of TC. TC ultrasonic degradation is mainly ascribed to OH oxidation, which is proved by results of quantum chemical calculations and LC-MS.(5) In comparison, the degradation effect of SD and TC in an aqueous solution by gamma irradiation of60Co source was better than ultrasonic in this research.