Study of the decomposition and detoxification of the herbicide bentazon by heterogeneous photocatalysis: Kinetics, intermediates and transformation pathways

摘要: Abstract Photocatalytic degradation and mineralization of the herbicide bentazon in aqueous solutions has been investigated. The pseudo-first order kinetics was studied under different operational conditions, such as type photocatalyst, catalyst loading, initial pH addition electron acceptors. rates proved to be strongly influenced by these parameters. Organic sulfur nitrogen were only partially converted into inorganic presence TiO2 P25 or Kronos vlp 7000 UV-A. H2O2 led either enhancement decrease rates, depending on employed. Intermediate products formed during photocatalytic treatment identified means a high resolution LIT Orbitrap LC-ESI/MS system. 21 intermediates including dimers, hydroxy and/or keto derivatives, further oxidized species detailed transformation pathways have proposed. Acute toxicity profiles using marine bacteria Vibrio fischeri showed an increasing trend at first stages oxidation, implying progressive formation more toxic than parent molecule, synergistic effects among products. Thereafter, ecotoxicity completely eliminated within 90 min irradiation investigated conditions. Phytotoxicity tests, carried out monocotyl Sorghum saccharatum dicotyls Sinapis alba Lepidium sativum, similar responses three plant photocatalytically treated samples, resulting complete removal phytotoxicity employed