Experimental Study On Degradation Of Amoxicillin In Water By γ - Ray Irradiation

Penicillin was the first antibiotic to treat human disease in humans，due to thewidespread production and use,and plus unique penicillin antibiotics in vivometabolism， metabolism of90%after the prototype discharged from the body，resulting in medical, domestic sewage discharge wastewater containing certain drugresidues.Because of penicillin antibiotics’biological inhibition and poorbiodegradability, it is difficult to degradate by biological treatment.As theenvironment and its metabolites in the gradual accumulation of penicillin, there is apotential threat to the human environment, antibiotic pollution has causedinternational environmental organizations and wide public concern.Degradation and mineralization of amoxicillin in aqueous solution by60Cogamma-ray irradation have been studied. and the influences of initial concentration ofamoxicillin， absorbed dose， pH value of solution， hydrogen peroxide(H2O2)，·OH radical scavengers (sodium bicarbonate and n-butanol) and dissolvedoxygen， etc.， were investigated. Explores the60Co γ-ray irradiation degradation ofamoxicillin in the water， the use of liquid chromatography analysis of amoxicillinradiolysis products tandem mass spectrometry， and further infer amoxicillindegradation pathway.Experimental results show that amoxicillin in aqueous solution can be effectivelydegraded by gamma-ray irradiation. When initial concentration of amoxicillin at10mg/L，the degradation efficiency of amoxicillin was close to100%at an absorbeddose of15kGy. Different concentrations of amoxicillin AMX has some influence onthe degradation rate， degradation rate of amoxicillin significantly decreased withAMX concentration increase. The decomposition yield was higher under alkalineconditions than in neutral and acidic media. With a radiation dose of10kGy，areduction of90%was achieved at pH11.Results obtained indicated that，atappropriate concentrations， H2O2accelerates amoxicillin degradation by generatingadditional·OH. However when the dosage of H2O2exceeds the optionalconcentration， the efficacy of amoxicillin degradation are reduced. Results show that the degradation rate of N2-saturated system is less than air-saturated system. A markeddecreased rate in N2-saturated system showed that·OH could promote AMXdegradation. The presence of·OH scavengers (sodium bicarbonate and n-butanol)significantly inhibited irradiation degradation of AMX. Which confirmed thatdegradation of AMX can take place via oxidation by·OH.The identification ofradiolytical products has been conducted using high chromatography tandem massspectrometry and possible pathways for further degration of amoxicillin were studied.After irradiation， six major radiolytical products with [M+H]+278，384，382，336，340，294were produced， which are detected in several different conditions，havebeen picked up. Possible pathways for further degration of amoxicillin were studied.Degradation of amoxicillin induced by γ-radiation was mainly ascribed to·OHoxidation.·OH which play a significant role in the degradation process， can attackamoxicillin acid molecule ring nitrogen atoms and β-lactam ring carbonyl， causingdegradation of amoxicillin.