Analysis of degradation of the micropollutant amoxicillin by photolysis and evaluation of the degradation products

Emerging micro pollutants are substances that have recently been identified in environmental matrices, of which information on environmental permanence and toxicity is still scarce. Because of their chemical structure, antibiotics are more stable and require more complex processes for degradation. The present study aimed to elaborate a proposal for the degradation of the β-lactam antibiotic amoxicillin by photolysis, evaluating the formation of by-products. As a methodology, 100 μg /L amoxicillin solutions were submitted to different ultraviolet lamp irradiations, at different potencies and distances, by means of a 100 mL batch quartz reactor. For the evaluation of the degradation of amoxicillin and of the products generated, the technique of high performance liquid chromatography with mass spectrometry was used. As a result, the best degradation condition (greater than 90% reduction of the original molecule) was with a 95W lamp, at a distance of 5 to 10 cm from the sample at 10 min irradiation time. Two by-products originated under different pH conditions of the irradiated solution were identified. Based on the obtained results, it is concluded that this prototype and the applied method can be used in the future to reduce this pollutant.