Photocatalysis using nanoscale catalysts and light emitting diodes
Date
2012
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Abstract
Recent advances in photo technology have led to the advent of inexpensive light emitting diodes (LEDs) which provide the opportunity to cut the operational cost of photochemical treatment significantly. LEDs offer several advantages over conver:,tional mercury lamps which include a . long life, efficient u_tilization of energy, approximately monochromatic light and can be operated in DC power making it operational at remote locations.
A photochemical study to degrade organics photocatalytically using dye-coated TiO2, TiO2 nanofiber, tin doped TiO2, platinum loaded TiO2 and P25 TiO2 under both visible and UV light has been investigated. Both fluorescent mercury lamp and LEDs were used as light sources. Laboratory scale investigations on i) the applicability of visible LEDs (A =436 nm) in degrading 4-chlorophenol (4-CP) by employing a dye (coumarin-343)-sensitized catalyst; ii) preparation of different nanoscale catalysts and their competitiveness with commercial catalyst in degrading 4-CP; and iii) photocatalytic dechlorination of polychlorinated biphenyls (PCBs) have been conducted. Subsequently a bench scale UV LED (A=365 nm) based photoreactor has been designed, fabricated and tested. Degradation of 4-CP by using a dye-sensitized catalyst under visible LED irradiation led to the generation of hydroxylated intermediates including ring opening. Laboratory studies on the competitiveness of the photocatalytic
activities of four different nanoscale catalysts, under UV light irradiation at 350 nm, and coumarin (C-343) coated TiO2 nanofibers at 436 nm light emitting diodes (LED) showed the promise of utilizing nano-scale catalysts in degrading 4-CP.
Photocatalytic dechlorination of polychlorinated biphenyls (PCBs) using platinum
loaded TiO2 (P25) in an alkaline 2-propanol medium was found to be successful. Bench scale batch experiments using a Rayonet photo-reactor under black lamp
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irradiation (11,=350 nm) showed complete dechlorination in a deaerated
environment. Enhanced photocatalytic efficiency was observed when platinum
loaded P25 was used as catalyst, with the best result being obtained when aqueous potassium hexachloroplatinate was added into the reaction medium.
Design of a novel bench-scale flow-through light emitting diode (LED) based photocatalytic reactor and testing of the same in degrading 4-CP, atrazine,
methylene blue (MB) under different conditions (bubbling oxygen, adding
hydrogen peroxide) showed promising results.
Description
Bibliography: p. 156-178
A few pages are in colour.
Includes copy of copyright permissions. Original copies with original Partial Copyright Licence.
A few pages are in colour.
Includes copy of copyright permissions. Original copies with original Partial Copyright Licence.
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Citation
Ghosh, J. P. (2012). Photocatalysis using nanoscale catalysts and light emitting diodes (Doctoral thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/4798