Visible-Light-Responsive Nanostructured Materials for Photocatalytic Degradation of Persistent Organic Pollutants in Water

Controllable synthesis and characterization of Mg2SiO4 nanostructures via a simple hydrothermal route using carboxylic acid as capping agent and their photocatalytic performance for photodegradation of azo dyes

Magnesium silicate (forsterite) nanoparticles were synthesized by a facile hydrothermal method, and characterized using several techniques such as XRD, SEM, EDS, DRS, Raman, TEM, and FT-IR. Several carboxylic acid structures were applied to modify the morphology and surface properties of the as-prepared particles. In this manuscript, citric acid, maleic acid, and succinic acid were used as the carboxylic acid agents. The effect of changing the ratio of carboxylic acid agent to central metal on the morphology and photocatalytic behavior was evaluated. The activities of the Mg₂SiO₄ nanostructures as photocatalysts were assessed by the degradation of several azo dyes (Acid Blue 92, Acid Brown 14, and Acid Violet 7) under UV and Vis light irradiation. The degradation percentages of Acid Blue 92 were about 88% and 74% in the presence of Vis and UV light respectively, and the percentages for photodegradation of Acid Brown 14 were approximately 76% and 82% in the presence of Vis and UV light, respectively. Furthermore, the degradation percentages for Acid Violet 7 were 93% and 80% under UV and Vis light, respectively.

Mg₂SiO₄ nanostructures have been synthesized via a facile hydrothermal approach. The photocatalytic behavior of Mg₂SiO₄ nanostructures prepared by different carboxylic acids have been investigated to degrade azo dyes under UV and visible light.

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

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.