Degradation of 2-chloropyridine in water by ultraviolet and ultrasound irradiation

The degradation of 2-chloropyridine in synthetic aqueous solutions by means of ultraviolet and ultrasound irradiation has been investigated. The effect of varying operating conditions (initial substrate concentrations from 100-500 mg/l, temperatures from 5-50 degrees C and liquid volumes from 50-500 ml) on degradation efficiency was evaluated. Light irradiation was generally more effective than ultrasound-driven degradation and complete substrate removal could be achieved in relatively short treatment times. On the other hand, ultrasound efficiency could be improved coupling cavitation with the Fenton reagents and selecting optimal reaction temperatures. The kinetics of 2-chloropyridine photodegadation at the conditions in question was found to be first order with respect to substrate concentration with reaction rates increasing with increasing temperature and decreasing concentration and liquid volume. The extent of total organic carbon photodegradation was substantially lower than that of the substrate itself indicating the formation of relatively stable by-products.