Photocatalytic Mineralization of Phenoxyacetic Acid Using Concentrated Solar Radiation and Titanium Dioxide in Slurry Photoreactor

Abstract

Heterogeneous photocatalysis offers an attractive alternative for wastewater treatment especially when treating low concentration of highly refractory pollutants. Phenoxyacetic acid (PAA) is a parent molecule of the well-known herbicides like 2,4-dichlorophenoxyacetic acid (2,4-D) and 2,4,5-trichlorophenoxyacetic acid (2,4,5-T), which are highly toxic compounds. The present work deals with photocatalytic degradation (PCD) of PAA in batch as well as in continuous photoreactor using concentrated solar radiation. The effect of various parameters such as adsorption, solution pH, initial concentration of pollutant, catalyst loading and types of anions in the solution were studied in batch reactor for its optimization. A comparison of PCD of PAA with 2,4-D shows that phenoxyacetic acid degrades more rapidly than 2,4-D under the otherwise identical conditions. The kinetics of photocatalytic degradation of PAA was also studied. A slurry bubble column reported earlier (Kamble et al., 2004) shows promising results for the treatment of wastewater from a plant manufacturing phenoxyacetic acid.