DEGRADATION OF THE ANTIBIOTICS AMOXICILLIN IN EFFLUENTS BY THE FENTON PROCESS
Issues related to water quality have been widely discussed, as it is a limited and essential natural resource for human activities, especially for human consumption, agricultural activities, and public and private supply. In addition to the degradation of water resources, the presence of persistent compounds in effluents, such as pharmaceuticals, personal care products, and metabolized compounds, has raised concerns due to their toxicity and environmental damage. These types of pollutants are often not removed by conventional wastewater treatment processes. In light of this, the present study contributed to the development and evaluation of an advanced oxidative process, specifically the Fenton-type process, for the degradation of amoxicillin in domestic sewage. To do this, the optimal concentration of iron (Fe2+) and hydrogen peroxide (H2O2) for Fenton reactions was determined, with a fixed treatment time of 60 minutes. Three Fenton-based treatments were proposed: (I) without a specific source of radiation; (II) using UV light; and (III) solar light as radiation sources. With a concentration of 500 mg L-1 of Fe2+ and 1500 mg L-1 of H2O2, removals > 80% were achieved for chemical oxygen demand and biochemical oxygen demand, > 98% for turbidity, and 100% of amoxicillin was degraded with a mineralization rate > 66%. Mass fragments corresponding to three amoxicillin degradation byproducts were found: 4-hydroxyphenylglycil AMX (515.1607 m/z, [C24H27N4O7S]+), penicilloic acid (394.1224 m/z, [C16H22N3O6S]+), and diketopiperazine amoxicillin (366.1118 m/z, [C16H20N3O5S]+), with these being found in higher concentration in the Fenton-solar process and lower in the UV radiation-assisted process. The toxicity of the treated effluent to the Lactuca sativa organism was evaluated, and the effects observed between the systems were different: effluents treated by the Fenton reaction and assisted by UV light showed no phytotoxic effects, while those treated by solar Fenton exhibited moderate phytotoxic effects on the test organism.