Removal of ethyl orange dye using hybrid chitosan and zinc oxide

Abstract

Ethyl Orange is a type of water-soluble azo dye, which is widely used in the textile, printing, paper manufacturing, pharmaceutical and food industries. Due to a large-scale production and extensive application of azo dyes, it can cause considerable amount of polluted wastewater and can generate serious health-risk factors. Chitosan, a low cost adsorbent has been widely used to treat azo dye. Recent studies had discovered heterogeneous photocatalysis using semiconductors such as zinc oxide is quite applicable because of its ability to decolorize dye-containing wastewater more effectively. The purpose of this research is to hybridize the low-cost adsorbent chitosan and semiconductor zinc oxide to produce an adsorbent which has high efficiency for removing azo dye. The parameters that were used in this study are pH values (pH 5.0 to 9.0), temperature (25 to 60°C) and the initial dye concentration (0.10 to 1.00 mg/L). The results obtained showed that hybrid chitosan and zinc oxide adsorbent had successfully decolorized ethyl orange dye in water. The optimum conditions for the highest removal of ethyl orange (85%) were achieved at following conditions; temperature of 60°C, using adsorbent containing 1 g of chitosan and 2.0wt % of zinc oxide, 1.0 mg/L of dye concentration, at pH 7 and 2 hours of mixing time with 130 rpm of mixing rate. In this study, the adsorption process was found to fit the Freundlich isotherm than of the Langmuir isotherm.