Effect of ZnO Nanoparticles on the Kinetics and Photo-degradation of Certain Textile Effluent Dyes

Abstract

Untreated effluents especially in discharges from textiles and fabric industries, usually contain dyes. Synthetic dyes have adverse effects on all forms of life when discharged directly into the environment. This paper investigates the photo-degradation of a mixture of direct orange 39, chlorantine fast red 5B, Viscose Black B and direct sky blue K, all present in a real textile effluent based on the influence of ZnO photocatalyst dose and irradiation time at a specific UV power source. The photo-degradation experiments were conducted in a batch stirred photoreactor equipped with UV lamp of rated at 30 W, a magnetic stirring system and a thermometer. The photocatalyst used was zinc oxide nanopowder (ZnO) The results showed that changes in these parameters influenced the efficiency of the photo-degradation. The kinetic studies showed that the dyes degradation followed the Langmuir-Hinshelwood model that has been modified to accommodate reactions occurring at the solid-liquid interphase. At the catalyst dose of 0.5 g/l, the apparent first order rate constant,  was 0.00411 ; but at 2.5 g/l, this reduced to . The best degradation was at the catalyst dose of 2.0 g/l with rate constant of .