Photodegradation of Amoxicillin in Aqueous Systems: A Review

Amoxicillin (AMX) is utilized in the treatment of several infectious diseases, and its concentration in wastewater has increased quite significantly over the years, posing high health hazards for humans and other living organisms. Investigations are in progress globally to eliminate AMX and other related pollutants using several methods that include adsorption, photolysis, photocatalytic degradation, photoelectrocatalytic degradation, and electrochemical conversion. AMX can be eliminated efficiently from the environment using photodegradation, either by photolysis or a photocatalytic process. Several types of semiconductor NMs have been used to eliminate AMX and other related drugs present in wastewater. This review spans the photodegradation studies conducted during the years 2018–2024 to degrade and eliminate AMX in aquatic systems. Several studies have been reported to eliminate AMX from different water streams. These studies are categorized into TiO₂-containing and non-TiO₂-based catalysts for better comparison. A section on photolysis is also included, showing the use of UV alone or with H₂O₂ or PS without using any nanomaterial. A tabulated summary of both types of catalysts showing the catalysts, reaction conditions, and degradation efficiency is presented. Researchers have used a variety of reaction conditions that include radiation types (UV, solar, and visible), pH of the solution, concentration of AMX, number of nanomaterials, presence of other additives and activators such as H₂O₂ as oxidant, and the influence of different salts like NaCl and CaCl₂ on the photodegradation efficiency. TiO₂ was the best nanomaterial found that achieved the highest degradation of AMX in ultraviolet irradiation. TiO₂ doped with other nanomaterials showed very good performance under visible light. WO₃ was also used by several investigators and found quite effective for AMX degradation. Other metal oxides used for AMX elimination were derived from molybdenum, zinc, manganese, copper, cerium, silver, etc. Some researchers have used UV and/or visible irradiation or sunlight, without using solid catalysts, in the presence of oxidants such as H₂O₂. A summarized description of earlier published reviews is also presented.