Degradation pathways of crystal violet by Fenton and Fenton-like systems: condition optimization and intermediate separation and identification.
The main advantage of Fenton's reagent (FR) over other OH systems is its simplicity. FR has the potential for widespread use in treating wastewater, but compared to other OH systems, little information on the dye degradation pathways of FR exists. The degradation of crystal violet (CV), a triphenylmethane dye, by FR was determined as a function of reagent concentration and ratio and pH in the batch treatment. The experimental results showed the optimum Fe(2+)/H(2)O(2) ratio to be 0.5mM:50mM and the optimum Fe(3+)/H(2)O(2) ratio to be 1mM:50mM. Optimal pH was about 3. To obtain a better understanding of the mechanistic details of Fenton reagent's degradation of CV dye, the intermediates of the process were separated, identified, and characterized by HPLC-PDA-ESI-MS and GC-MS techniques in this study. Indications were that the probable degradation pathways were N-de-methylation and cleavage of the conjugated chromophore structure. The intermediates were generated in the order of the reaction time and relative concentration, indicating that the N-de-methylation degradation of CV dye is a major reaction pathway. The reaction mechanisms proposed in this research should prove useful for future application of the technology to the decolorization of dyes.
Fan
Huan-Jung
HJ
Department of Environmental Engineering, Hungkuang University, Taichung 433, Taiwan, ROC.
Huang
Shiuh-Tsuen
ST
Chung
Wen-Hsin
WH
Jan
Jeng-Lyan
JL
Lin
Wan-Yu
WY
Chen
Chiing-Chang
CC
D002851:Chromatography, High Pressure Liquid / Q000379:methods; D002853:Chromatography, Liquid / Q000379:methods; D004396:Coloring Agents / Q000737:chemistry; D005840:Gentian Violet / Q000737:chemistry*; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D017665:Hydroxyl Radical / Q000737:chemistry; D007220:Industrial Waste; D007501:Iron / Q000737:chemistry*; D008745:Methylation; D008956:Models, Chemical; D010126:Ozone; D021241:Spectrometry, Mass, Electrospray Ionization / Q000379:methods; D014865:Waste Disposal, Fluid; D018508:Water Purification / Q000379:methods
D004396:Coloring Agents; C045076:Fenton's reagent; D007220:Industrial Waste; D017665:Hydroxyl Radical; D010126:Ozone; D006861:Hydrogen Peroxide; D007501:Iron; D005840:Gentian Violet