Electrochemical oxidative degradation of indigo wastewater based on chlorine-containing system

Abstract

Purpose

In this study, the oxidative degradation performance of indigo wastewater based on electrochemical systems was explored. The decolourization degrees, removal rate of chemical oxygen demand and biochemical oxygen demand of the indigo wastewater after degradation were evaluated and optimized treatment conditions being obtained.

Design/methodology/approach

The single factor method was first used to select the electrolyte system and electrode materials. Then the response surface analysis based on Box–Behnken Design was chosen to determine the influence of four independent variables such as FeCl₃ concentration, NaCl concentration, decolourization time and voltage on the degradation efficiency.

Findings

On the basis of single factor experiment, the electrode material of stainless steel was selected in the double cell, and the indigo wastewater was electrolyzed with FeCl₃ and NaCl electrolytes. The process conditions of electrochemical degradation of indigo wastewater were optimized by response surface analysis: the concentration of FeCl₃ and NaCl was of 16 and 9 g/L, respectively, with a decolourization time of 50 min, voltage of 10 V and decolourization percentage of 98.94. The maximum removal rate of chemical oxygen demand reached 75.46 per cent. The highest ratio of B/C was 3.77, which was considered to be more biodegradable.

Research limitations/implications

Dyeing wastewater is bringing out more and more pollution problems to the environment. However, there are some shortcomings in traditional technologies such as adsorption and filtration. As a kind of efficient and clean water treatment technology, electrochemical oxidation has been applied to the treatments of various types of wastewater. The decolourization and degradation of indigo wastewater is taken as an example to provide reference for the treatment of wastewater in actual plants.

Practical implications

The developed method provided a simple and practical solution for efficiently degrading indigo wastewater.

Originality/value

The method for the electrochemical oxidation technology was novel and could find numerous applications in the degradation of printing and dyeing wastewater.

Citation

Zhang, W., Lv, W., Li, X. and Yao, J. (2020), "Electrochemical oxidative degradation of indigo wastewater based on chlorine-containing system", Pigment & Resin Technology, Vol. 49 No. 1, pp. 46-54. https://doi.org/10.1108/PRT-08-2019-0070