| Chloramphenicols (CAPs) have been known for their antibacterial activity against bacteria, which are common phenicol antibiotics widely used. They played a key role on protecting human life and health from desease. Nowadays, CAPs resistance has become a global threat because of existing antibiotics which are becoming increasingly ineffective in combating microbial infections in humans. CAPs residuals in animal derived food caused a potential risks on the food safety issues. Food safety issues caused by CAPs happened every year, which bring a negative impact to society, human health and international trade.In the present work, Chloramphenicol (CAP), Thiamphenicol (THA) and Florfenicol (FLO) were studied. Their degradation characteristics and mechanism were studied by e-beam, photolysis and pulse radiolysis.Firstly, e-beam was used to investigate the decomposition mechanics of CAPs, and the primary products of the e-beam degradation were identified. The results showed that the different concentrations of CAPs impacted theirs decomposition rates to some extent, and the degradation rate decreased with the increasing of initial concentration. The degradation rates were above 80% at the irradiation doses of 20kGy. CAPs degradation rates could be increased by adding H2O2; At pH=3, the degradation rate also increased because the·OH enhanced the degradation rate. N2-saturated system was observed, and the results showed that the degradation was decreased than air-saturated system.Inorganic anions such as Cl-, SO42- and F- which discharged into the water body directly have been elucidated. The concentrations of Cl- or SO42- increases with the absorbed dose up to 15 or 20 kGy, and the F-concentration is low due to releasing HF. The aqueous THA and FLO solutions can effectively be degraded by the reaction of-OH-adduct and-H-abstract to result in the reactive radical fractions, and ultimately mineralized. Secondly, the pulse radiolysis was adopted to study the instantaneous reactions process of CAPs, and the reactions speed of CAPs with·OH, e-aq and·H in varies conditions were calculated to explore the degradation mechanism. The results indicated that the reaction pathway between CAPs and OH was dominated by the initial solution pH value. In neutral condition, the addition reaction happed between·OH and benzene ring. But in basin condition, the organic bond·OH was removed by·OH. The dechlorination of these three substances was caused by e-aq attacking while the·H only added on the benzene ring forming relative stable products. Furthermore, the radiolysis degradation of CAPs by-products were identified by gas chromatography -mass spectrum analysis and their degradation pathway were also conducted.Thirdly, the photo-induced degradation of CAPs was studied under the UV and simulated sunlight irradiation. The decomposed mechanisms were ensured by addition of H2O2 and saturated with nitrogen in the solutions, and the reaction constants were also calculated. In this work, the xenon lamp was used to simulated sunlight. It was found that the CAPs could be decomposed under both UV and xenon lamp illumination and the by-products were identified to study the degradation process. These results would be a powerful theory for the CAPs antibiotics rational applied in human and animals.In addition, the method for high concentration of CAPs products practical wastewater treatment irradiated by E-beam was erected. At initial CAP concentration of 0.18mg/L, the treated wastewater was lower than detection limits and in accord with the nation standard law after 30 kGy dose irradiation. Comparing to other methods, the E-beam irradiation showed great promise due to its low irradiation dose, little space and time, highly efficient treatment of refractory organic wastewater. This research would be helpful for the further rational use of CAPs antibiotic and treatment of CAPs contaminated water in the future.
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