Photocatalytic degradation of 2,4-dicholorophenoxyacetic acid by TiO₂ modified catalyst: kinetics and operating cost...

Effective pesticide remediation technology demands amendments in the advanced oxidation process for its continuous treatment and catalyst recovery. The evidence of 2,4-dichlorophenoxyacetic acid (2,4-D), an herbicide in water bodies, poses a major environmental threat to both humans and aquatic organisms. In the present study, a recirculation type photocatalytic reactor was developed to treat 2,4-dichlorophenoxyacetic acid using chitosan-TiO₂ beads prepared via impregnation method under UV light. At optimized conditions, chitosan-TiO₂ beads showed a maximum photocatalytic degradation of 86% than commercial TiO₂ (65%) and followed pseudo first-order reaction. The 2,4-D degradation follows pseudo first-order kinetics under UV irradiation with a rate constant of 0.12 h^-1, and the intermediates were identified using LCMS analysis. The total operational cost of the chitosan-TiO₂ catalyst was found to be profitable (Rs. 1323 for 2 L) than that of TiO₂ (Rs. 1679) at optimized conditions. The beads were reusable up to 4 consecutive cycles without loss in efficiency. This study briefs photocatalytic removal of 2,4-dichlorophenoxyacetic acid in a recirculation-type reactor for its reliability, low cost, efficiency, reusability, and commercialization.