Treatment of levafix orange textile dye solution by electrocoagulation

Abstract

The decolorization of the levafix orange textile dye in aqueous solution by electrocoagulation using aluminum sacrificial anode has been investigated. The process performance is analyzed in terms of decolorization efficiency and the important cost-related parameters such as electrode and energy consumptions, as a function of initial pH, conductivity, current density, initial dye concentration and electrolysis time. The present study proves the effectiveness of electrochemical treatment for the textile dye solution. 95% decolorization efficiency may be obtained at suitable operating conditions such as; current density 100 A/m², operating time 12 min and initial pH 6.4. The corresponding electrode and energy consumptions during the electrolysis were found to be 1.8 kg Al/kg dye and 35 kWh/kg dye.

Introduction

Textile industries use large amount of water and chemicals for finishing and dying processes. Dye wastewater usually consists of a number of contaminants including acids, bases, dissolved solids, toxic compounds, and colored materials which are noticeable even at very low concentrations and need to be removed before the wastewater can be discharged.

Traditional methods for dealing with textile wastewater consist of various combinations of biological, physical and chemical methods [1], [2]. Biological treatment of dying wastewater is cheaper than other methods, but it is less efficient for decolorization due to toxicity of the wastewater and the need for an aeration system. Although the dyestuff and colored materials in wastewater can be effectively destroyed by advanced chemical oxidation such as UV/H₂O₂, O₃ [3], [4] and adsorption using activated carbon [5], [6], the costs of these methods are relatively high for an economically feasible treatment of the textile wastewater. The electrocoagulation (EC) technique is considered to be potentially an effective tool for treatment of textile wastewaters with high removal efficiency.

EC is a process consisting of creating metallic hydroxides flocs within the wastewater by electrodissolution of soluble anodes, usually made of iron or aluminum. Electrocoagulation has been applied successfully for treatment of potable water [7], food and protein wastes [8], textile wastewater [9], [10], aqueous suspensions containing kaolinite, bentonite and ultrafine particles [11], [12], fluoride containing water [13], [14], restaurant wastewater [15], [16], textile dyes solutions [17], [18], and smelter wastewater containing harmful arsenic [19].

The objective of the present study is to investigate the decolorisation of a reactive textile dye (Levafix Orange E3 GA) in aqueous solution using aluminum as non-toxic and readily available electrode material. Several parameters, namely initial pH, conductivity, current density, dye concentration and electrolysis time, were investigated for their effects on the decolorisation efficiency. The corresponding electrode and energy consumptions are also determined as principal cost parameters.