In recent years, the presence of drug residues in water has become a major environmental issue. Among these pollutants is amoxicillin. Our aim is to propose effective methods for decontaminating wastewater containing amoxicillin. This study was carried out using the chemical oxygen demand method. This work has shown that hydroxyl radicals can effectively degrade amoxicillin. The rate of hydroxyl radical production from hydrogen peroxide and iron (II) ions increases in the presence of sunlight. Amoxicillin oxidation is optimal at a pH of 3 and a [H2O2]/[Fe2+] ratio of 13.33. Amoxicillin degradation is faster at low concentrations than at high concentrations. The oxidation of amoxicillin by photo-Fenton results in degradation rates of up to 99%. A study of the adsorption of amoxicillin on copper oxides showed that amoxicillin adsorbs weakly to the amoxicillin surface, with an adsorption rate of 17%. However, in the presence of amoxicillin, hydrogen peroxide and sunlight, degradation rates of up to 99% were obtained. This work has shown that the degradation of amoxicillin is better with solar photo Fenton and solar photocatalysis in the presence of copper oxide than with the Fenton process.