Investigating the Efficiency of the UV/Iodide/ZnS Process for the Removal and Degradation of Methotrexate From Aqueous Solutions

In the current century, the consumption of cytostatic drugs such as methotrexate, known for their mutagenic and teratogenic properties, has increased due to the rising prevalence of cancer. Given methotrexate’s poor metabolic breakdown in the human body, its residues have been detected in hospital effluents and treated wastewater, underscoring the necessity for its removal from aquatic environments. This study aimed to evaluate the efficacy of the UV/iodide/ZnS process in removing methotrexate from aqueous solutions. Key variables, including pH, catalyst concentrations (iodide and ZnS), initial methotrexate concentration, and contact time, were investigated. Optimized conditions derived from synthetic solutions were compared with real hospital wastewater samples, and methotrexate levels were quantified via high‐performance liquid chromatography (HPLC). Results revealed that optimal methotrexate removal (81%) and mineralization (55%) in synthetic media were achieved using the ZnS/iodide/UV process under the following conditions: pH 7, 2 mM iodide, 0.2 g/L ZnS, and 20‐min contact time. Individual and synergistic analyses of the process demonstrated that the simultaneous application of all three oxidizing agents (ZnS, iodide, and UV) yielded significantly higher efficiency than combined or individual treatments. When applied to hospital wastewater under optimized conditions, methotrexate removal and mineralization efficiencies were reduced to 45.5% and 23%, respectively. These findings highlight the UV/iodide/ZnS process as an environmentally friendly advanced oxidation/reduction technology with promising efficacy for methotrexate removal from aqueous solutions. Under optimized parameters, the method achieves rapid degradation and holds potential for real‐scale implementation in advanced and tertiary wastewater treatment systems.