APPLICATION OF TIO2 SEMICONDUCTORS FOR THE SIMULTANEOUS DEGRADATION OF NAPROXEN, DICLOFENAC, AND MEFENAMIC ACID IN SURFACE WATERS

Abstract

The presence of contaminants, especially pharmaceuticals, in concentrations ranging from ng L–1 to μg L–1 has been the focus of numerous studies and is considered an emerging concern due to their adverse effects on aquatic biota and even human health. In this context, this study aimed to optimize a photoreactor equipped with four 24 W ultraviolet (UV)-A lamps and thin films of silver-doped titanium dioxide (Ag/TiO2), evaluating parameters such as catalyst concentration, pharmaceutical concentration, matrix effects, and pharmaceutical quantification using high-performance liquid chromatography (HPLC). The immobilized Ag/TiO2 catalysts were used for the photodegradation of the pharmaceuticals naproxen, diclofenac, and mefenamic acid. Photocatalysis tests were initially conducted in ultrapure water, followed by dispersive liquid-liquid microextraction with solidification of floating organic drops (DLLME-SFOD) on a real sample from São José Bay (Maranhão, Brazil) to identify the pharmaceuticals present and evaluate the degradation process. Naproxen and diclofenac were detected in the environmental sample, and results showed that photolysis alone was insufficient to degrade the compounds in brackish water. Therefore, photocatalytic treatment using Ag/TiO2 was necessary, achieving 100% degradation of diclofenac in 7 h, 100% of mefenamic acid in 4 h, and 90% of naproxen in 10 h. This research highlights the effectiveness of the optimized photoreactor with Ag/TiO2 thin films in treating real matrices to achieve high drug degradation rates.