Heat-activated potassium persulfate treatment of Sudan Black B dye: Degradation kinetic and thermodynamic studies

Water-soluble dyes are common persistent organic pollutants present in textile wastewater, which are associated with environmental pollution and health hazards. The conventional effluent treatment methods are not efficient to remove these dyes from textile wastewater. Heat activated persulfate based wastewater treatment is a promising advanced oxidation process (AOP) for the treatment of textile wastewater. Therefore, the main objective of the present work was to study the degradation of Sudan Black B (SBB) dye in aqueous solution by varying activation temperature (40-60 degrees C), KPS dosage (250-750 ppm), and initial dye concentration (20-50 ppm). The dye degradation was found in a range of 35%-100% for varied experimental conditions. Removal percentages were improved by the increase of temperature, time, and persulfate concentration but decreased with the increase of initial dye concentration. The kinetic study indicated that the degradation of SBB dye using KPS followed first order model with rate constants varied in a range of 0.15 x 10(-2) - 40.5 x 10(-2) min(-1). Standard reaction enthalpies (Delta H degrees) standard Gibbs free energies (Delta G degrees), activation energies (E-a), standard entropies (Delta S degrees) were found in a range of 190 - 505 kJ.mole(-1), -33.0 - 0.6 kJ, 73 - 222 mole(-1),0.6-1.6 kJ/K for different sets of experimental conditions, respectively. Degradation reactions of SBB dye were endothermic (Delta H degrees+ve); non-spontaneous (Delta G degrees +ve) at 40 degrees C, but spontaneous (Delta G degrees+ve) at other temperatures (50 degrees C and 60 degrees C). Therefore, it can be predicted that heat-activated persulfate is an efficient method to achieve faster degradation of dye in the treatment of industrial wastewaters containing SBB dye.

Automated summary

The study demonstrates that heat-activated persulfate is a promising method for efficiently degrading water-soluble dyes in textile wastewater. By adjusting temperature, time, and persulfate concentration, removal rates of the dye can be enhanced. Kinetic study reveals that the degradation of the dye follows a first-order model.