Recovery of Sodium Sulphate from Process Waste of H-Acid Industry | Original Article

ABSTRACT:

India is the second largest manufacturer of H-Acid in the world after China. H-acid is dye intermediate compound used in manufacturing of reactive dyes (To prepare dyeazo coupling in dye manufacturing). Due to its high pollution potential and high treatment cost, most of the countries not allowed H-Acid manufacturing in their countries. Due to usage of high strength acids and alkalies during manufacturing of H-acid, the combined wastewater stream is contaminated with high sulphate content. Sodium salts (Na2SO4) get accumulated in H-acid slurry. Decahydrate Sodium sulphate (Na2SO4.10H2O4) known as Glauber's salt and widely used in several industries like pharmaceutical, detergents, glass, paper etc. In H-Acid industry, Glauber’s salt is contaminated with mother liquor of H-Acid and contains reddish tinge which hamper market value and industry has sent it to Hazardous Waste disposal site hence it is necessary to find-out economical and sustainable Sodium Sulphate recovery technique. We studied impact of Temperature, pH variation, use H2O2 oxidizing agent and coagulating agent to recover desired grade of sodium sulphate by removing unwanted impurities. It observed that, after double filtration of Glauber’s salt slurry followed by oxidation and polyelectrolyte treatment then achieved 98% pure Sodium Sulphate crystals. This study is helpful to minimize waste, reduces treatment and disposal cost as well as reduce the production cost and product become economically viable to the industry.