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Comparative photocatalytic degradation of monoazo and diazo dyes under simulated visible light using Fe3+/C/S doped-TiO2 nanoparticles

William Anku, Samuel Osei-Bonsu Oppong, Sudheesh Kumar Shukla, Poomani Penny Govender


This research work delved into the photocatalytic degradation of monoazo dye (methyl orange) and diazo dye (congo red) in aqueous solution using Fe3+/C/S-doped TiO2 nanocomposites. The nanocomposites were synthesised through sol-gel method and characterized using XRD, FTIR, SEM, TEM, EDX, BET and UV-Vis. Photocatalytic degradation of the dyes was monitored under simulated visible light using pristine TiO2, C/S/doped-TiO2 and Fe3+/C/S doped-TiO2 with varying concentrations of Fe3+. The influence of catalyst doping, solution pH, and light intensity were also examined.  Doping TiO2 with Fe3+/C/S caused reduction in its band gap value with the resultant improvement in its visible light activity. The photocatalytic efficiency of the catalysts are given as follows: TiO2 < C/S/TiO2 < Fe3+/C/S-TiO2 with Fe3+/C/S-TiO2 (0.3 % Fe3+) as the best performing photocatalyst. The monoazo dye experienced higher degradation efficiency than the diazo dye. Degradation of the azo dyes was observed to decrease with increasing pH from 3 to 12. Increased visible light intensity enhanced the photodegradation efficiency of the dye. Dye decolourization was observed to be faster than its mineralization.


TiO2; metals; non-metals; azo dyes; photocatalytic degradation; sol-gel method

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Copyright (c) 2016 William Anku, Samuel Osei-Bonsu Oppong, Sudheesh Kumar Shukla, Poomani Penny Govender

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