Kinetic Modeling of Photocatalytic Degradation of an Azo Dye Using Nano-TiO 2 /Polyester

Abstract

Abstract

Photocatalytic degradation of Reactive Orange 16 (RO16) was investigated using immobilized TiO₂ nanoparticles on polyester support in exposure of UV irradiation in recirculated tubular photoreactors. Utilization of the polyester as a support has several advantages, such as low price, remarkable surface area, flexibility, and durability. Moreover, the prepared TiO₂/polyester was successfully applied for the photocatalytic degradation of RO16 in aqueous media for several times without any discernible diminution in its activity. Applied TiO₂ nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). Experimental results indicate that the degradation rate of RO16 follows pseudo-first-order kinetics. With nonlinear regression, a model was developed for prediction of pseudo-first-order rate constants (k_app) as a function of operational parameters, including temperature (295–328K), flow rate (5–15 L·min⁻¹), and initial concentration of RO16 (5–25 mg·L⁻¹) as \documentclass{aastex}\usepackage{amsbsy}\usepackage{amsfonts}\usepackage{amssymb}\usepackage{bm}\usepackage{mathrsfs}\usepackage{pifont}\usepackage{stmaryrd}\usepackage{textcomp}\usepackage{portland, xspace}\usepackage{amsmath, amsxtra}\pagestyle{empty}\DeclareMathSizes {10} {9} {7} {6} \begin{document} $$k_{\rm app} = 2.20 ( \exp { [- 7427 / \rm RT} ]) ( FR ) ^{0.5034} [ {0.112 / (1 + 0.112 [ \rm RO16 ] _0} )] .$$ \end{document} Calculated data from the model are in good agreement with the experimental results. Electrical energies per order (E_EO) were estimated from the calculated and experimental data show that E_EO depends on the operational parameters, considerably. To monitor the mineralization of RO16, chemical oxygen demand (COD) measurements were carried out during the UV/TiO₂ process. COD measurement results indicated that all organic substances were completely mineralized after 5 h of UV irradiation.