Physicochemical Study of Photocatalytic Activity of TiO2Supported Palygorskite Clay Mineral

Lahcen Bouna,Benaissa Rhouta,Francis Maury

doi:10.1155/2013/815473

Abstract

This study deals with the influence of physicochemical parameters, namely, the photocatalyst loading, dye concentration, and pH of polluted solutions, on the degradation efficiency of Orange G (OG) solutions containing TiO2nanoparticles supported on palygorskite clay mineral (TiO2-Pal). The TiO2photocatalyst attached to natural palygorskite fibers was elaborated by colloidal sol-gel route. It exhibits the anatase structure that is the most photoactive crystallographic form. The highest performances of supported photocatalyst on OG degradation were found using an optimum amount of TiO2-Pal around 0.8 g·L−1, which corresponds properly toca. 0.4 g·L−1of TiO2. This amount is interestingly lower than the 2.5 g·L−1generally reported when using pure unsupported TiO2powder. The photodegradation rate increases by decreasing OG initial concentration, and it was found significantly higher when the OG solution is either acidic (pH<4) or basic (pH≈11). For OG concentrations in the range5×10-6– 5×10-4 M, the kinetic law of the OG degradation in presence of TiO2-Pal is similar to that reported for unsupported TiO2nanopowder. It follows a Langmuir-Hinshelwood model with a first-order reaction and an apparent rate constant of about2.9×10-2 min−1.

Highlights

Heterogeneous photocatalytic oxidation recently has emerged as an efficient alternative process for wastewater treatment [1,2,3,4,5]
This study deals with the influence of physicochemical parameters, namely, the photocatalyst loading, dye concentration, and pH of polluted solutions, on the degradation efficiency of Orange G (OG) solutions containing TiO2 nanoparticles supported on palygorskite clay mineral (TiO2-Pal)
Because the optimization of experimental conditions is very important in designing a slurry reactor for effective and efficient use [4], we have investigated in the present work the effects of physicochemical parameters on photocatalytic activity of TiO2 supported palygorskite fibers in order to find out the best conditions permitting an efficient removal of OG dye

Summary

Introduction

Heterogeneous photocatalytic oxidation recently has emerged as an efficient alternative process for wastewater treatment [1,2,3,4,5]. Among the support materials envisaged, clay minerals are considered promising owing to their interesting inherent properties as their adsorption capacity, high surface area, multiscale porosity, and ability to be bound to chemical compounds [6,7,8,9] In this respect, we reported recently the immobilization of TiO2 anatase nanoparticles (NPs) with an average size of 10 nm onto particle surfaces of beidellite [10] and fiber surfaces of palygorskite [11] via a colloidal sol-gel route. Because the optimization of experimental conditions is very important in designing a slurry reactor for effective and efficient use [4], we have investigated in the present work the effects of physicochemical parameters on photocatalytic activity of TiO2 supported palygorskite fibers in order to find out the best conditions permitting an efficient removal of OG dye This pollutant was selected as model compound because it is widely used in the textile industry

Experimental Details

Results and Discussion

Conclusion