Degradation of the micropollutant amoxicillin by photolysis and evaluation of the toxicity of byproducts generated in aquatic environments

Antibiotic micropollutant are present in the environmental and is necessary the development of effective treatment to eliminate this from the water. The present study aims to propose the degradation of β-lactam antibiotic amoxicillin by photolysis and evaluate the formation of other organic structures and the metabolite toxicity. Solutions of 100 µg L −1 of amoxicillin were used. They were subjected to different conditions of irradiation by ultraviolet lamp with different powers, distances through a reactor in batch of quartz and pH solution of 4, 7 and 9. To assess the degradation of amoxicillin and the products generated, high-performance liquid chromatography coupled with mass spectrometry was used. The best degradation condition was 90% reduction of the original molecule and was obtained with a 95 W lamp 5–10 cm from the sample and irradiation time of 10 min. Two products originated under different pH conditions of irradiated solution were identified, namely amoxicillin penicilloic acid ( m/z 384) and amoxicillin 4-hydroxyphenilglyl ( m/z 515). Based on the results, the best treatment condition requires adjusting the pH to 9 and the irradiation time to 10 min. There is no toxicity in this condition. This results in a greater potential for degradation with less toxicity of the resulting solution. We conclude that this prototype and the applied method can be used in a water treatment system in the future.