Photocatalytic Degradation of Sulfamethoxazole from a Synthetic Pharmaceutical Wastewater Using Titanium Dioxide (TiO2) Powder as a Suspended Heterogeneous Catalyst

Abstract

Some medications in aquatic media pose a serious environmental risk. Sulfamethoxazole (SMX) is a member of the sulfonamide group. Photocatalysis offers a promising technique to degrade organic pollutants into environmentally friendly substances. This study examined the effect of operating conditions (pH, time, and temperature) of the ultraviolet (UV)/TiO₂ photocatalytic process on the degradation of SMX in an aqueous solution. Decreasing the pH value positively affects SMX degradation, and better removal values were obtained at a pH equal to 4. The optimum operating conditions for complete degradation in a solution containing 500 mg/L of SMX, TiO₂ 0.5 mg/L irradiation time of 420 min, and pH 4. Under these conditions, Chemical Oxygen Demand (COD) removal was 62.6% at a temperature of 25 ℃. The effect of temperature was studied at three temperatures (25, 40, and 60 ℃) with pH 4. The elevation of temperature increased the COD removal rate to 99.62% at 60 ℃. Finally, the results of the reaction kinetics study showed that a first-order kinetics model described organic contamination removal data over time, and the obtained activation energy was 42.195 kJ/mol.