Photo-degradation of carbamazepine using TiO2 suspended photocatalysts

Abstract

Carbamazepine (CBZ), a persistent pharmaceutical compound, cannot be effectively removed (<10%) by conventional wastewater treatment plants. This study investigates the removal of this molecule in water solution using a photocatalytic process at 365 nm. Five commercial TiO2-based photocatalysts (P90, P25, UV100, PC500, and ST01) were tested over a range of operating parameters (type and concentration of photocatalysts, pH, treatment time, and light intensity). The best operating conditions for CBZ degradation in solution (99% CBZ removal) were obtained using P90 as photocatalyst at a concentration of 1.5 g/L for 90 min of treatment with a pH of 5.0 and a light intensity of 18.9 W/m2. Under these conditions, removal of 74% of total organic carbon was recorded. This optimized photocatalytic process can treat either relatively high concentrations of CBZ (5 mg/L to 20 mg/L) or low concentrations of CBZ (37 µg/L) in water. The initial rate of photocatalytic degradation of CBZ using P90 as photocatalyst can be described by the Langmuir–Hinshelwood (L–H) kinetic model with a reaction rate constant of 2.22 ± 0.003 mg/L/min at ca. 20 °C.