Photocatalytic Removal Of 2, 4- Dichlorophenoxyacetic Acid And Quinclorac Herbicides By An Immobilized System Of Carbon Coated, Nitrogen Doped And Polyene Sensitized TiO2

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Date
2017-05
Authors
Ahmad Sabri, Nur Nazrina
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Universiti Sains Malaysia
Abstract
An immobilized system of carbon coated, nitrogen doped and polyene sensitized TiO2 (CNTiO2/EP-10h) was fabricated using epoxidized natural rubber (ENR50) and polyvinyl chloride (PVC) as the binders through a dip coating technique. The optimum amount of photocatalyst and PVC binder in the coating formulation were 6 g and 0.8 g, respectively, while 2.29 mg cm-2 was the best amount of photocatalyst composite loading. The photo-etching process for 10 hours (10h) reduced the band gap energy of the photocatalyst from 2.91 to 2.86 eV, creating a highly porous photocatalyst surface as well as oxidizing the PVC binder to be a conjugated polyene that sensitized TiO2. The efficiency of CNTiO2/EP-10h for photocatalytic degradation of 2,4-dichlorophenoxyacetic acid (2,4-D) was determined under UV-Vis, total visible and solar light irradiations. The best photocatalytic removal of 2,4-D was obtained under UV-Vis light followed by solar and total visible lights. The optimized conditions for photocatalytic removal of 2,4-D by CNTiO2/EP-10h under UV-Vis, total visible and solar light irradiations were found to be at pH 3 with an aeration flow rate of 40 mL min-1. The complete mineralization of 2,4-D by CNTiO2/EP-10h was achieved after 6 hours under solar light irradiation. The LC-MS analysis detected dichlorophenol, dichlorocatechol, dichlororesorcinol, chlorohydroquinone, hydroxyhydroquinone, phenol, muconic and fumaric acid as the intermediate products from the photocatalytic removal of 2,4-D. The application of CNTiO2/EP-10h was also extended to the photocatalytic degradation of quinclorac (QNC). The removal of QNC by CNTiO2/EP-10h became faster in the order of total visible < UV-Vis < solar light irradiation.
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Photocatalytic removal of 2, 4- dichlorophenoxyacetic acid , by an immobilized system of carbon coated
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