Photooxidative N-de-ethylation of anionic triarylmethane dye (sulfan blue) in titanium dioxide dispersions under UV irradiation.
The TiO(2)-mediated photocatalysis process has been successfully applied to degradation of dye pollutants. Our results indicate that the TiO(2) surface is negatively charged, and the sulfan blue (SB) adsorbs onto the TiO(2) surface through the positive di-ethylamino groups while the TiO(2) surface is positively charged and the SB adsorbs onto the TiO(2) surface through the negative sulfonyl groups. In order to obtain a better understanding of the mechanistic details of this TiO(2)-assisted photodegradation of the SB dye with UV irradiation, five intermediates of the processes were separated, identified, and characterized by the HPLC-ESI-MS technique, which included a positive- and negative-ion mode. The results indicated that the N-de-ethylation process continues until the N-de-ethylated SB dye is completely formed. The probable photodegradation pathways were proposed and discussed. The reaction mechanisms of UV/TiO(2) proposed in this study should be useful for future applications of the technology to the decolorization of dyes.
Chen
Chiing-Chang
CC
Department of General Education, National Taichung Nursing College, Taichung 403, Taiwan, ROC.
Lu
Chung-Shin
CS
Mai
Fu-Der
FD
Weng
Chyan-Syang
CS
D000327:Adsorption; D000838:Anions / Q000737:chemistry; D002851:Chromatography, High Pressure Liquid; D005030:Ethylenes / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D015394:Molecular Structure; D010084:Oxidation-Reduction; D010777:Photochemistry; D012394:Rosaniline Dyes / Q000737:chemistry*; D021241:Spectrometry, Mass, Electrospray Ionization; D013057:Spectrum Analysis; D014025:Titanium / Q000737:chemistry*; D014466:Ultraviolet Rays
D000838:Anions; D005030:Ethylenes; D012394:Rosaniline Dyes; C009495:titanium dioxide; C036216:ethylene; D014025:Titanium; C008769:sulfan blue