Decolorization of AR18 dye solution by electrocoagulation: sludge production and electrode loss in different current densities

Abstract

A lab-scale electrocoagulation batch reactor was used to remove acid red 18 as an azo dye by use of aluminum electrodes. The effects of different parameters including initial pH, current density, reaction time, initial dye concentration, distances between electrodes, and type of the electrolyte solution on the efficiency of EC process were investigated. The influence of the current densities on consumed anode and produced sludge was also studied. Optimum conditions were obtained at pH 4. Removal percentage of the dye was significantly increased with increasing current density until reaching to critical point of 26 mA/cm². Anode mass reduction was increased from 202 mg at current densities of 26 mA/cm² to 331 mg at 42 mA/cm². Moreover, mass of produced sludge was increased from 605.85 to 1,060 mg with a net mass of 400-mg sludge production. The shorter distances between electrodes resulted in higher decolorization. Type of the electrolyte solution was an important parameter affecting the amount of the consumed electrolyte or energy required for decolorization.

Keywords:

• Aluminum electrodes
• Azo dyes
• Decolorization
• Electrocoagulation process
• Textile wastewater

Acknowledgment

The authors gratefully acknowledge the financial and technical support for this study that was provided by Ardabil University of Medical Sciences, Ardabil, Iran.