Degradation of linuron by ultrasound combined with photo-Fenton treatment

Sonochemical photodegradation of linuron, which is one of phenylurea herbicides, was carried out in the presence of Fe(II). The degradation rate was strongly influenced by initial concentration of Fe(II) and solution pH. The optimal Fe(II) concentration and pH were found to be 1.2 × 10−4 mol L−1 and 3.0, respectively. An initial linuron concentration of 10 mg L−1 was completely degraded by ultrasound/Fe(II)/UV system after 20 min under the optimum conditions while only 79.3% of linuron was decomposed under ultrasonic irradiation. Furthermore, the first-order rate constant in ultrasound//Fe(II)/UV process (0.17 min−1) was about 2 times greater than that in ultrasonic alone (0.08 min−1). The decrease of TOC as a result of mineralization of linuron was observed during the combination process. The complete linuron mineralization was achieved after 120 min. The formations of chloride, nitrite and nitrate ions as end-products were observed during the degradation system. Based on these results, ultrasound/Fe(II)/UV system would be useful technology for the treatment of water samples containing linuron.