TR Sundararaman, V Ramamurthi and N Partha
Keywords: Color removal, lignite, chemical coagulation, dyes
Abstract: Lignite soil was found to be an effective coagulant aid for color removal of textile dyes from aqueous solutions. A comparative study with conventional coagulant had been done. Results show that lignite soil can effectively remove reactive, vat and disperse dyes from their 50mg/L aqueous solutions. Parameters such as color, settled sludge volume have been evaluated. Results showed an increase of color removal, reduction in settled sludge volume when lignite soil was used as coagulant aid with alum and MgCl2. It was found that color removal for reactive blue, vat blue and disperse red was 93%, 92%, 96% for alum, 100% respectively for all dyes with alum and lignite, 100%, 80%, 92% for MgCl2 and 100% respectively for all dyes with magnesium chloride and lignite. For the textile waste water, the color removal was found to be 85% and 91% for alum and alum with lignite, 84% and 90% for MgCl2 and MgCl2 with lignite. The mechanism for coagulation by lignite was found to be a charge adsorption neutralization process. The optimum pH range for lignite coagulant was from 3 to 6. It was found that the settled sludge volume reduced from 90ml to 55ml, and 150ml to 75ml when lignite was used as coagulant aid for alum and MgCl2, for reactive dyes, 50ml to 10ml and 80ml to 30ml when lignite was used as coagulant aid for alum and MgCl2 for vat dyes, 78ml to 55ml and 92ml to 78ml when lignite was used as coagulant aid for alum and MgCl2 for disperse dyes and 84ml to 55ml and 100ml to 80ml when lignite was used as coagulant aid for alum and MgCl2 for textile waste water.
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