Investigations on the degradation of an antibiotic Cephalexin using suspended and supported TiO2: Mineralization and durability studies

Rising levels of antibiotics in treated wastewater pose a great threat to human health worldwide. The present study shows degradation studies of antibiotic Cephalexin using slurry and innovative fixed-bed photocatalysis under UVA (365nm) irradiations. A UV-spectrophotometer/HPLC was used for analyzing the decay of Cephalexin. Studies showed that variation in UV intensity, dose variation of TiO2 and H2O2, area by volume (A/V), and pH affect the degradation to a great extent. The degradation rate followed pseudo-first order kinetics with optimized conditions for degrading the antibiotic being TiO2 1.0g center dot L-1, H2O2 0.15mL, with UV intensity of 25W center dot m(-2). The COD decrease (80%) with the generation of nitrite, nitrate, and sulphate ions confirmed the mineralization of the selected compound. TiO2-coated spherical cement beads were used for fixed-bed studies, which eliminates the implications of slurry mode photocatalysis. The beads were recycled for at least 50 cycles, which confirmed the durability of the catalyst, and characterized by SEM-EDAX. Attempts were made to study the pilot-scale fixed-bed baffled solar reactor for degrading Cephalexin, which confirmed 70% degradation after 10h.