Photocatalytic Degradation and Kinetics of Dyes in Textile Effluent Using UV – ZnO-Al System

Abstract

This study investigates the photodegradation of a mixture of 4 azo dyes (direct orange 39, chlorantine fast red 5B, viscose black B and direct sky blue K) present in textile effluents and the influence of catalyst dose, irradiation time, UV power intensity on the overall photodegradation kinetics of the process. The photocatalytic experiments were conducted in a batch stirred photoreactor equipped with a 10 W, 30W and 60 UV lamps, magnetic stirrer and thermometer. The photocatalysts used was zinc oxide nanoparticle doped with aluminium (AZO, 15nm, 99.99 to %). The results obtained showed that variation in the physical parameters influenced the efficiency of photodegradation. The kinetic study indicated that the photodegradation of the dyes present in the effluent from the textile industry followed the Langmuir-Hinshelwood model that is modified to accommodate reactions occurring at a solid-liquid interphase. At the catalyst dose of 0.5g/l, the apparent first order rate constant K1, was 0.00615 min-1 but at 2.5g/l it reduced to 0.00567 min-1. The best degradation was at the catalyst dose of 2.0g/L with the rate constant of 0.0134 min-1.