Removal of phenylurea herbicide monuron via riboflavin-mediated photosensitization

• Published in: Chemosphere (Oxford) 2007-09, Vol.69 (2), p.177-183
• Main Authors: Chu, W., Chan, K.H., Jafvert, C.T., Chan, Y.S.
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Applied sciences; Biological and medical sciences; Biological and physicochemical phenomena; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; Herbicides - isolation & purification; Methylurea Compounds - isolation & purification; Monuron; Natural water pollution; Optimal dose; Photochemistry; photolysis; Photosensitizer; photosensitizers; Pollution; Pollution, environment geology; remediation; Ribavirin - chemistry; Riboflavin; Soil and water pollution; Soil science; ultraviolet radiation; Ultraviolet Rays; Water treatment and pollution
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2007.04.055

Photodegradation of the phenylurea herbicide monuron by using riboflavin (Rf), a sensitizer, was investigated by varying the doses of monuron and Rf in this work. An enhanced photochemical effect was observed in the process compared with the direct photolysis by using UV irradiation only. The reaction time was greatly shortened from more than 60 min (direct photolysis) to 8–30 min depending on the doses of initial concentration of monuron ([M] 0) and Rf. A modified hyperbola model was found to be useful to determine the reaction kinetics and thereafter the performance on the photodegradation of monuron sensitized by Rf. Two measurable characteristic constants (initial decay rate and total removal index) were used to quantify the reaction. The maximum removal difference compared with the direct photolysis and Rf-sensitization was investigated. It was found that the improvement of the process depended on both the [M] 0 and the doses of Rf.