Removal of COD from Industrial Effluent Containing Indigo Dye Using Adsorption Method by Activated Carbon Cloth: Optimization,Kinetic, and Isotherm Studies

The pollution of underground and surface water streams is a tremendous environmental problem. Adsorption, in which activated carbon (AC) is used as an adsorbent, is one of efficient procedures to remove organic and inorganic pollutants from industrial wastewaters. Activated carbon fiber (ACF), a newly developed form of AC, has high adsorption rate and surface area and can be used for the treatment of industrial wastewaters. In this work, ACF was prepared by physicochemical activation method from kenaf and we studied its ability in the treatment of indigo‐containing wastewater produced from a dying factory. The filtered wastewater was treated via adsorption by ACF, and response surface experimental design method was used to study the effect of ACF dosage, contact time, temperature, and pH of the wastewater on the removal process. ACF dosage of 0.256 g, temperature of 12.5°C, pH 8.5, and contact time of 125 min were optimum treatment conditions. The adsorption process obeys pseudo‐second‐order kinetic and Freundlich isotherm models.     

Decolourisation of textile indigo dye by DC electric current

The electrochemical technology has been employed for the treatment of soils and liquid medium contaminated with aromatic pollutants as indigo textile dye. In liquid medium, 76% of colour removal was obtained in 87 h, and the addition of NaCl (10 g/l) reduced the treatment time up to 45 min. In soils, two alternative methods were developed: a direct electrochemical treatment and the extraction of dye from the soil followed by electrochemical decolourisation of the liquid collected. In the latter process, 50% ethanol in water solution was selected as the best extracting agent. This extracting solution (indigo concentration of 0.5 g/l) was further decolourised electrochemically in the presence of NaCl (10g/l) for 24 h, ending in a colour removal of 70%. Using the direct electrochemical treatment, a regular decolourisation profile along the whole cell was attained. The decolourisation degree was 76% and was reached after 16 days of treatment and an electric power consumption of 61 W·h.