Degradation of amoxicillin residue under visible light over TiO2 doped with Cr prepared from tannery wastewater

Abstract

The degradation of amoxicillin residue has been performed using TiO2 photocatalyst doped with Cr prepared from tannery wastewater under visible light exposure. The incorporation of Cr metal into TiO2 structure was conducted via hydrothermal method. From the characterization results, it is found that doping Cr from the tannery wastewater into TiO2 structure has been successfully shifted the light absorption into visible region. Among the various Cr content in the TiO2-Cr photocatalyst, TiO2-0.33Cr (medium level) shows the highest ability in the visible light absorption, suggesting it to be the best photocatalyst. It is also clearly proven that in the presence of TiO2-0.33Cr photocatalyst, the degradation of amoxicillin can reach almost 100 % after the third cycles. Furthermore, this study also investigated the optimum condition for photodegradation of amoxicillin as the prevalent antibiotic residue in batch technique. The concentration of amoxicillin after the photodegradation process was determined using a UV–visible spectrophotometer. The result identifies the optimal condition for the amoxicillin photodegradation is reached at pH 6, with 10 mg of the photocatalyst mass per 30 mL of the sample solution, and an irradiation time at 90 min. The photodegradation of amoxicillin using TiO2-0.33Cr follows the pseudo-first order kinetic model with kinetic constant (k) is high as 0.004 min−1.