Sonochemical degradation of the antibiotic cephalexin in aqueous solution

The degradation of cephalexin in aqueous solution under ultrasound irradiation was investigated. Biodegradability of the solution was evaluated by the BOD5/COD ratio, which was raised from zero to 0.36 after ultrasound treatment, indicating that the ultrasound irradiation process is a successful pre-treatment step to improve the biodegradability of cephalexin solution. The influences of ultrasound power and pH value on the degradation of cephalexin were studied. It was found that the optimal ultrasound power for cephalexin degradation in the system was 200 W and the rate of cephalexin degradation was maximal in the pH range of 6.5 to 8.5. The degradation kinetics of cephalexin in aqueous solution under various operational conditions was also investigated. It was found that the degradation of cephalexin follows a pseudo-first order kinetics.