Nano Photo Catalytic Degradation of the Pharmaceutical Agent Balsalazide Under UV Slurry Photo Reactor

The presence of pharmaceuticals and personal care products (PPCPs) as trace pollutants in natural surface water bodies, ground water and drinking water has recently led to some concern. Advanced oxidation processes (AOPs), which utilize free radical reactions to degrade chemical contaminates, are an alternative to traditional water treatment. Anti-inflammatory drug balsalazide (as model compounds) besides actual wastewater samples were UV photodegraded using suspended titanium silicon oxide (TiSiO₄) or UV/H₂O₂/O₂ systems. The photodegradation was favourable in the pH 8–12.8 range. The effect of various parameters such as photocatalyst amount, balsalazide (BSZ) concentration, pH of aqueous solution, irradiation time, addition of H₂O₂ and temperature on photocatalytic oxidation was investigated. The kinetics of the photocatalytic oxidation of BSZ in aqueous TiSiO₄ suspensions was investigated as a function of catalyst loading (2–12 mg/L) and the concentration of BSZ (0.01–0.05 mg/mL) at pH 11.5. The optimum conditions for the degradation of the BSZ have been found as 0.045 mg/mL drug concentration, pH 11.5 and 0.1 g/L catalyst dose. The results indicated that the photocatalytic degradation of BSZ was well described by pseudo-first-order kinetics according to the Langmuir–Hinshelwood model. The effect of temperature on the efficiency of photodegradation of BSZ was also studied in the range 278–298 K. The activation energy was calculated according to Arrhenius plot and was found equal to 24 ± 1 kJ mol⁻¹ for TiSiO₄. Decolourization and mineralization of BSZ in the absence of light and/or catalyst were performed to demonstrate that the presence of light and catalyst is essential for the decolourization of this BSZ. This work adds to the global discussion on the role of the advanced oxidation processes in water treatment.