Decolorization of triphenylmethane dyes and dye-doped silica microspheres using sodium percarbonate

ABSTRACT Three triphenylmethane (TPM) dyes, namely brilliant green, basic fuchsin, and crystal violet were decolorized using sodium percarbonate (SPC) in the practical decolorization of TPM dyes in wastewater. The decolorization conditions such as pH, temperature, bleaching time and the dosage of oxidant were examined based on the decolorization percentage change. Under the optimal conditions, the decolorization percentage of three TPM dyes averagely reaches around 90% in 20 min at pH 11 and room temperature (20°C). The optimal dosage of SPC was determined for the three TPM dyes respectively. The TPM-doped silica microspheres were synthesized by the Stöber method and characterized by UV-Vis, IR, and TEM techniques. The synthesized TPM@SiO 2 microspheres were also decolorized effectively by sodium percarbonate. The degradation mechanism of the amino- or alkylamino-TPM dyes is proposed based on the UV-Vis analyzes, by which the degradation process could undergo two dominant reactions: the destruction of conjugated structure and N-dealkylation reaction. This study verifies the viability of the use of sodium percarbonate for the wastewater treatment of TPM dyes.