title: Photocatalytic degradation of herbicide bentazone in aqueous suspension of TiO2: mineralization, identification of intermediates and reaction pathways.
abstract: Semiconductor-mediated hydrogen peroxide-assisted photocatalytic degradation of a selected herbicide, Bentazone (1) has been investigated in aqueous suspensions of TiO2 under a variety of conditions. The degradation was studied by monitoring the depletion in total organic carbon content as a function of irradiation time. The degradation kinetics was investigated under different conditions such as type of TiO2 (Anatase/Anatase-Rutile mixture), reaction pH, catalyst dosage and hydrogen peroxide (H202) concentration. The degradation rates were found to be strongly influenced by all the above parameters. Titanium dioxide Degussa P25 was found to be more efficient as compared with other two commercially available TiO2 powders like Hombikat UV100 and PC500 from Millennium Inorganic Chemicals. Gas Chromatography-Mass Spectrometry (GC-MS) analysis of the irradiated mixture of Bentazone (1) indicates the formation of several intermediate products which have been characterized on the basis of molecular ion/mass fragmentation pattern and also on comparison with the National Institute of Standards and Technology (NIST) library. Plausible mechanism for the formation of different products during photocatalytic treatment of Bentazone in the presence of TiO2 has been proposed. The use of H202 substantially increased the efficiency of TiO2 photocatalytic degradation.
authors.affiliation: Department of Chemistry, Aligarh Muslim University. Aligarh 202002, India.
authors.forename: Niyaz A
authors.initials: NA
authors.lastname: Mir
authors.affiliation: Department of Chemistry, Aligarh Muslim University. Aligarh 202002, India.
authors.forename: M M
authors.initials: MM
authors.lastname: Haque
authors.affiliation: Department of Chemistry, Aligarh Muslim University. Aligarh 202002, India.
authors.forename: A
authors.initials: A
authors.lastname: Khan
authors.affiliation: Department of Chemistry, Aligarh Muslim University. Aligarh 202002, India.
authors.forename: M
authors.initials: M
authors.lastname: Muneer
authors.affiliation: SAIF CRNTS, IIT Bombay, Powai, Mumbai 400076, India.
authors.forename: S
authors.initials: S
authors.lastname: Vijayalakshmi
mesh_terms: D001581:Benzothiadiazines / Q000737:chemistry* / Q000302:isolation & purification / Q000528:radiation effects; D006540:Herbicides / Q000737:chemistry* / Q000302:isolation & purification / Q000528:radiation effects; D008027:Light; D008903:Minerals / Q000737:chemistry*; D010777:Photochemistry / Q000295:instrumentation / Q000379:methods; D012666:Semiconductors; D013535:Suspensions; D014025:Titanium / Q000737:chemistry* / Q000528:radiation effects; D014867:Water / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000302:isolation & purification / Q000528:radiation effects; D018508:Water Purification / Q000295:instrumentation / Q000379:methods*
chemical_list: D001581:Benzothiadiazines; D006540:Herbicides; D008903:Minerals; D013535:Suspensions; D014874:Water Pollutants, Chemical; D014867:Water; C009495:titanium dioxide; D014025:Titanium; C002003:bentazone