Significant mineralization of beta blockers Propranolol and Atenolol by TiO2 induced photocatalysis

Degradation of wastewater containing recalcitrant pharmaceuticals is one of the emerging problems. Photocatalytic degradation and mineralization of two beta blockers Propranolol (PR) and Atenolol (AT) was investigated in TiO2 suspension. Four commercially available TiO2 samples viz. Aeroxide P25, Hombikat UV 100, Kronoclean 7000 and Merck TiO2 were used in which, Aeroxide TiO2 P25 was found to give best photocatalytic activity for both the pollutants studied under UV light as well as simulated solar light irradiation. The key experimental parameters such as effect of concentration of photocatalyst (0.05g/L to 0.4g/L), substrate concentration (1×10-5 Mto 1×10-4 M for PR and 9×10-5 Mto 3×10-4 M for AT), initial pH of the reaction sample (acidic, neutral and basic) and effect of addition of H2O2 (0.02mM-0.12mM H2O2) were studied in detail and optimized. Degradation of pollutants was assessed spectrophotometrically at 214 and 224 nm for PR and AT respectively, while mineralization data was obtained by Chemical Oxygen Demand (COD) and Total Organic Carbon (TOC) measurements. Mineralization studies (COD) highlight the dramatic enhancement in mineralization efficiency for PR and AT both under photocatalytic degradation as compared to photolysis alone. Aeroxide TiO2 P25 showed good recyclability and reusability up to three consecutive cycles without hampering its efficiency