Oxidation mechanisms of amoxicillin and paracetamol in the photo-Fenton solar process

The present study shows the results of solar photo-Fenton oxidation of paracetamol (PCT) and amoxicillin (AMX). Fe2(SO4)3 was used as the source of iron and EDDS as the iron complexing agent, employing different doses of hydrogen peroxide. Two aqueous matrices, a synthetic wastewater and real wastewater from El Ejido WWTP effluent (Almeria) were used. In all cases, the process was operated under conditions of natural sunlight. Results showed that the degradation of both drugs is favoured when the aqueous matrix presents low concentration of carbonates. Under the conditions studied here, degradation percentages above 90% were obtained in the synthetic wastewater and 80% in the actual effluent. The degradation products were determined using liquid chromatography coupled to high-resolution mass spectrometry with hybrid quadrupole time-of-flight analyser. The intermediates detected throughout the oxidative process for both micro-contaminants were mainly products of hydroxylation reactions. The toxicity of the samples was determined using the bacterium Vibrio fischeri. In the acute toxicity test, it was observed that the bacteria did not undergo inhibition in any of the cases. However, chronic toxicity studies showed that the higher the Hydraulic Retention Time (HRT) employed in the assays, the higher the bacterial inhibition. [Display omitted] •Solar photo-Fenton successfully degraded microcontaminants under natural sunlight and circumneutral pH.•90% and 80% degradation percentages were obtained in the synthetic wastewater and actual effluent.•In acute toxicity tests, bacteria did not undergo inhibition in any of the cases.