Decolouration of Dye Solutions Using Photoelectrocatalysis and Photocatalysis
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Terry A Egerton
,
Herry Purnama
Abstract
This paper compares the photocatalytic and photoelectrocatalytic decolouration of dilute solutions of two dyes, one, methylene blue, cationic and one, reactive orange, anionic. For both methylene blue and reactive orange there is evidence that, as in photocatalytic decolouration, the initial stage in photoelectrocatalytic degradation is the destruction of the chromophore responsible for absorption in the visible region of the spectrum. For both dyes, both photoelectrocatalysis and photocatalysis were more efficient at pH > 9 than at pH 4. For the cationic dye, methylene blue, photoelectrocatalytic degradation was slower than photocatalytic degradation - indeed even though photocatalytic decolouration of 0.2 mM methylene blue solutions could be achieved photoelectrocatalytic degradation was negligible under the conditions used by us. However, photoelectrocatalytic decolouration of 0.1 mM methylene blue solution was achieved. The reduced efficiency of photoelectrocatalysis probably occurs because adsorption of the dye molecules on the TiO2 surface is a necessary first step in photocatalysis and because the positive potential on the photanode reduces adsorption of the cationic methylene blue. For the anionic dye, reactive orange, photoelectrocatalytic degradation was more effective, under the conditions of our experiment. However, the rate of decolouration was approximately the same as that of photocatalytic degradation by a TiO2 immobilized on a non-woven paper. The rate of both photocatalytic and photoelectrocatalytic degradation of the negatively charged Reactive Orange was faster at pH 10 than at pH 7, even though at the higher pH the surface of the TiO2 may be expected to be more negatively charged.
© 2016 by Walter de Gruyter Berlin/Boston
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Articles in the same Issue
- Preface
- Removal of PAHs from Creosote Oil Contaminated Soil by Addition of Concentrated H2O2 and Biodegradation
- Kinetics of Wet Oxidation Reactions
- Biodegradability Enhancement of Wastewater Containing 4-Chlorophenol by Means of Photo-Fenton
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- TiO2/C Photocatalyst Prepared by Ethanol Vapour Treatment of TiO(OH)2
- Effects of Carbon Coating on TinO2n-1 for Decomposition of Iminoctadine Triacetate in Aqueous Solution under Visible Light
- Hybrid Plasma-Catalyst System for the Removal of Trichloroethylene in Air
- Photocatalytic Oxidation of Emerging Contaminants: Kinetics and Pathways for Photocatalytic Oxidation of Pharmaceutical Compounds
- Photocatalytic Degradation of four Textile Azo Dyes in Aqueous TiO2 Suspensions: Practical Outcomes and Revisited Pathways
- Decolouration of Dye Solutions Using Photoelectrocatalysis and Photocatalysis
- Aged Raw Landfill Leachate: Membrane Fractionation, H2O2/UV Treatment and Molecular Size Distribution Analysis
- Electrochemical Treatment of Trace Endocrine Disrupting Chemicals with a Three-Dimensional Electrode System
- Semiconductor Mediated Photocatalysed Degradation of a Pesticide Derivative, Acephate in Aqueous Suspensions of Titanium Dioxide
- Hexavalent Chromium Remediation by Bore-Hole Placed Reduction Barriers and Monitored Natural Attenuation
