STUDIES ON REMOVAL OF COTTON BLUE DYE FROM AQUEOUS SOLUTION USING ELECTROCOAGULATION

Abstract

Dyes and Dye Intermediates industry is an important sector of the Indian Chemical Industry. The Indian companies together account for around 7.0% of the world production. Dyes and pigments are widely used in textile, leather, paper, plastic, food and other industries. Many dyes and pigments have toxic as well as carcinogenic, mutagenic and teratogenic effects on aquatic life and also on humans. Various treatment processes used for the removal of dyes from the waste water include electro-coagulaton, adsorption, photochemical, coagulation and sedimentation, membrane separation, biological treatment, etc. EC process provides a simple, reliable and cost-effective method for the treatment of wastewater without any need for additional chemicals, and thus the secondary pollution. It also reduces the amount of sludge, which needs to be disposed. In the present study, electro-coagulation using aluminum electrodes has been used for the removal of Cotton Blue dye from the aqueous solution. Batch studies were conducted to see the effects of various parameters like pH, inter electrode distance, applied voltage, number of electrodes, initial concentration of Cotton blue dye, and electrolysis time on the removal of Cotton Blue dye. The efficiency of the method tested was determined by measurement of color removal. For dye solutions with COD of approximately 42 mg/1 and dye concentrations of 100 mg/I, high dye removal (97%, i.e., color falls from an initial value of 1400 to 22 Pt-Co units) was obtained when the pH ranged from 6 to 8, time of electrolysis was approximately 15 min, applied voltage was approximately 11 V, number of electrode was six, and inter-electrode distance was 0.5 cm. During the EC process under these conditions, COD reduction was found to be — 74 % and TOC removal was 61.4 %. Small difference between color diminution has been found with the progress of treatment. Percent removal decreases with increase in initial concentration of Cotton blue. Optimized operational conditions were applied to real textile wastewater which led to satisfactory color removal (more than 95%) though electrolysis time and anode consumption is more in case of real textile waste water.