Abstract

The textile industrial wastewater with number of dyes including inorganic and organic compounds is very polluted if it is not controlled before discharging into environment. Thus, colour wastewater treatment technology and decolourization efficiency are necessary. The aim of this study is to evaluate the removal efficiency of acid orange 7 (AO7) which has been using at large range in the textile industry by homogeneous ozone process. Decolourization of aquatic solutions containing Acid Orange 7 with initial concentration of 110ppm by using semi-batch reactor where transferred ozone from gas to liquid with initial concentration of 5ppm O3 was studied. The highest decolourization of AO7 solution, about 80%, was achieved at pH3 after 1 hour-treatment time. This efficiency decreased with increasing the initial pH, namely 75%, 60%, 55% and 39% for pH 5, 7, 9, 10, respectively. The decolourization process of AO7 by homogenous ozonation was considered following by the second order kinetics and kinetic constants of the decolourization of AO7 were confirmed the ability of ozonation for decolourization of this dye. The rate constants of decolourization of AO7 were higher at pH 3, 5 with 2.6594M-1s-1, 1.8827 M-1s-1, respectively and lower at pH 7, 9, and 10 with 0.8624M-1s-1, 0.8979M-1s-1 and 0.7777 M-1s-1, respectively. The results obtained shows the homogeneous ozonation capability can be applied to remove AO7 dye.

Keywords:Textile wastewater; Acid orange 7; Homogeneous ozone process; Decolourization