Modeling perchloroethylene degradation under ultrasonic irradiation and photochemical oxidation in aqueous solution

Sonolysis and photochemical degradation of different compounds such as chlorinated aliphatic hydrocarbons areamong the recent advanced oxidation processes. perchloroethylene is one of these compounds that has beenmainly used as a solvent and degreaser. in this work, elimination of perchloroethylene in aqueous solution byultrasonic irradiation, andphotochemical oxidation by ultra violet ray and hydrogen peroxide were investigated.three different initial concentrations of perchloroethylene at different ph values, detention periods, andconcentrations of hydrogen peroxide were investigated. head space gas chromatography with fid detector wasused for analyses of perchloroethylene. this research was performed in 9 months from april through december2011.results showed that perchloroethylene could be effectively and rapidly degraded by ultrasonic irradiation,photochemical oxidation by ultra violet ray, hydrogen peroxide and a combination of these methods. kinetics ofperchloroethylene was strongly influenced by time, initial concentration and ph value. degradation ofperchloroethylene increased with decrease in the initial concentration of perchloroethylene from 0.3 to 10 mg/l atall initial ph. the results showed an optimum degradation condition achieved at ph = 5 but did not affectsignificantly the perchloroethylene destruction in the various ph values. kinetic modeling applied for the obtainedresults showed that the degradation of perchloroethylene by ultrasound and photo-oxidation followed first orderand second order model. the percentage of removal in the hybrids reactor was higher than each of the reactorsalone, the reason being the role of hydroxyl radical induced by ultrasound and photochemical reaction.