Solar activation of periodate for the effective degradation of reactive blue 222 dye: optimization, generated by-products, and real textile wastewater

This article presents the activation of periodate (PI) under simulated sunlight (SSL) for the removal of reactive blue 222 dye (RB-222). Further, the degradation system was evaluated using real industrial effluents, and the utilization of natural sunlight as a light source for the degradation of RB-222 dye was assessed, both of which have been poorly explored in the literature. The optimization study revealed that a removal efficiency of 99.9% could be accomplished at an initial dye concentration of 5 mg/L, PI concentration of 4.7 mM, temperature of 70 °C, light intensity of 0.013 W/cm 2 , pH 7, and reaction time of 90 min. The replacement of SSL with natural sunlight under the optimal conditions could achieve a removal percentage of 98%, affirming the applicability of the remediation system under sunlight. Quenching tests exhibited the main participation of iodate radicals and singlet oxygen in the degradation system over other radicals. The degradation system could remove 69.4% of the total organic carbon in real effluents compiled from a textile factory. The generated by-products were determined, and the toxicity assessment by Ecological Structure Activity Relationships affirmed the toxicity reduction of the generated intermediates. The proposed remediation system is promising for the practical application due to its high performance under sunlight and cost-effectiveness.