Removal of hydrophobic dyestuff from dyeing wastewater by photo-sensitization process

Recently, photochemical reaction became more important in view of using UV in textile dyeing wastewater treatment processes, in which neither chemical sludges nor toxic residues are left in the treated effluent. The photodegradation of hydrophobic dye (Palanil Yellow 5R, PY-5R) in the presence of acetone, which performs as a solvent and/or a photo-sensitizer, was investigated in this study. The results demonstrated that photochemical reaction in the presence of acetone could rapidly and effectively enhance color removal at a wavelength of 253.7 nm. The photodegradation follows pseudo first-order decay. The rate constants and decay quantum yields of dye degradation by UV depend on the solution pH and solvent system, (i.e., acetone to water ratio). The photosensitization of the disperse dye was found to be optimized at pH 9 and in 0.5 (v:v) acetone-water ratio.