Electrooxidation for the removal of Sulfamethoxazole using graphite electrodes

Sulfamethoxazole is a sulfonamide class antibiotic commonly used to cure infections caused by bacteria in humans and animals. Sulfamethoxazole is considered a contaminant of emerging concern and is one of the most frequently found antibiotics in the environment. It has proven to be highly stable and persistent in the environmental matrices, with a half-life of more than 100 days in an aqueous environment under specific environmental conditions. This causes a severe threat to human and environmental health. The presence of residue of sulfamethoxazole in water matrices shows hazardous effects on aquatic life, affecting the physiological behaviour and reproductive capacity of aquatic organisms. Sulfamethoxazole also showed potential negative impacts on the microbial communities. The persistence of these compounds for an extended period in the environment leads to the formation of antibiotic-resistant genes in bacteria, which can affect the proper functioning of the ecosystem. In this current study, the effectiveness of the electrooxidation process on the removal of sulfamethoxazole using graphite electrodes was investigated. The effect of different parameters like the electrolysis time, current density, initial concentration of sulfamethoxazole, electrolyte concentration (NaCl or Na₂SO₄), and initial pH of the sample solution were evaluated. Out of the various parameters, it was found that current density (1-10 mA/cm²), electrolyte concentration (100- 500 mg/ L), and the electrolysis time (0-1h) are the key parameters that determine the efficiency of the electrooxidation treatment process. It was found that for the current density value of 10 mA/ cm², within 45 min of electrolysis time, nearly 99% of the sulfamethoxazole degradation occurred. The possible sulfamethoxazole degradation mechanisms and resulting by-products were analyzed using the Liquid chromatography-mass spectroscopy (LC-MS). Degradation kinetics were also evaluated for the electrooxidation treatment process. The results from the current study showed that electrooxidation could be a favourable treatment technique for the removal of sulfamethoxazole from water matrices.