Removal of Reactive Black 5 dye from aqueous solutions by coupled electrocoagulation and bio-adsorbent process

Textile wastewater contains a significant amount of bio dye compounds including Reactive Black 5 (RB5) as an Azo dye that causes serious damage to the environment and aquatic life in receiving water resources. It is estimated that approximately 15% of the dyestuff is discharged into water bodies and 50% of those are Azo dyes.

The aim of this study was to examine the effectiveness of combining electrocoagulation and bio-adsorption methods using the active carbons from Kenya tea waste to remove RB5 from aquatic solutions.

Experiments were done in wastewater and the Wastewater laboratory of Gonabad University of Medical Sciences in 2017. Initially, iron electrodes were installed in a 1 L glass container and connected to electrical power with primary dye concentration of 500 mg/l, EC 1000-3000 μs/cm, adsorbent dosage of 0.2-1.0 mg/l, pH 2-9 and electrical potential 30 V. After that, the samples were collected at twenty-minute intervals until the eightieth minute. Performance of dye removal was measured using spectrophotometer techniques (597 nm). Finally, the data were analyzed by descriptive statistics using Microsoft Excel 2017 version.

The findings of this study demonstrated that the highest simultaneous removal performance (96%) was obtained by pH 6, 80-minute reaction time, and EC 3000 μs/cm. With the increasing of reaction time, the energy consumption, electrodes wear, pH, final temperature of effluent, and removal efficiency would increase. Adsorption process could play a small role in the removal of the dye, while it was very effective in improving the performance of the electrocoagulation process.

A combination of the electrocoagulation and adsorption processes can be adopted as an efficient and economical way to treat effluents contaminated with dyestuff.