Abstract

Abstract A novel, simple and simultaneous synthesis-immobilization of nano ZnO on perlite (nZnO-P) as a photocatalyst for photocatalytic degradation of Acid orange 7 (AO7) in aqueous solution was investigated. The effect of operational parameters such as initial dye concentration, initial pH, flow rate, photocatalyst granule size, temperature and the kinetic of the removal of AO7 in terms of the Langmuir-Hinshelwood model in a designed semi batch packed bed photoreactor connected to an on-line sampling UV-Vis spectrophotometer was studied. The results showed that AO7 removal efficiency increased with nZnO-P using the designed setup and the proposed photocatalyst was more efficient than TiO2 as a standard catalyst. Our results confirmed the pseudo-first-order kinetics model. The values of the adsorption equilibrium constant, KAO7, the kinetic rate constant of surface reaction, kc, and the activation energy (Ea) were found to be 0.57 (mg.l−1)−1, 0.41 mg.l−1.min−1 and 11.44 kJ/mol, respectively.

Highlights

  • Wastewater from textile, paper and some other industries contain residual dyes which are not readily biodegradable

  • The present study envisages the simultaneous synthesis-immobilization of ZnO on the granular perlite as a new photocatalyst and its effect on the photocatalytic degradation of Acid orange 7 (AO7) in designed packed bed photoreactor

  • The degree of degradation of AO7 was calculated at different time intervals using the equation given below: In which X is the degree of degradation, C0 is the initial concentration of AO7, and Ct is the concentration of AO7 at time t

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Summary

INTRODUCTION

Wastewater from textile, paper and some other industries contain residual dyes which are not readily biodegradable. Adsorption and chemical coagulation processes are two common techniques of wastewater treatment These methods merely transfer the dyes from the liquid to the solid phase causing secondary pollution and requiring further treatment. Advanced oxidation processes (AOPs) are alternative techniques of removing dyes and many other organics in wastewater and effluents. These processes generally, involve UV/H2O2, UV/O3 or UV/Fenton’s reagent and etc, for the oxidative degradation of contaminants. The present study envisages the simultaneous synthesis-immobilization of ZnO on the granular perlite as a new photocatalyst and its effect on the photocatalytic degradation of AO7 in designed packed bed photoreactor. All experiments have been performed using the designed semi batch packed bed photoreactor connected to an on-line sampling UV-Vis-spectrophotometer

MATERIALS AND METHODS
Procedures
RESULTS AND DISCUSSION

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