Alkali and Chlorine Products, Sodium Carbonate

Abstract

AbstractSodium carbonate, Na2CO3, formula wt 105.99, is a white crystalline solid known as soda ash and, less commonly, ash, soda, or calcined soda. It is readily soluble in water and in strongly alkaline. It is the eleventh largest world commodity chemical. About 75% of world production is synthetic ash made from sodium chloride and limestone via the Solvay or similar processes; the remaining 25% is produced from natural sodium carbonate‐bearing deposits. Over half of the world's production is consumed in the glass industry, and another 22% is used in the production of sodium‐based chemicals. Sodium carbonate is also used in detergents, pulp and paper, and environmental control (water treatment and flue gas desulfurization). The normal article of commerce is highly purified (\documentclass{article}\usepackage{amssymb}\pagestyle{empty}\begin{document}${{\rm{>}}99{\%}}$\end{document}). Aqueous solutions are alkaline. At 25°C the pH of 1, 5, and 10 wt % Na2CO3solutions is 11.37, 11.58, and 11.70, respectively. Under National Fire Production Association (NFPA) Designation 704, soda ash is classified as a moderate health hazard. Exposure to soda ash dust may cause severe eye and slight nose and throat irritation. Traditional synthetic soda ash plants produce large volumes of aqueous, chloride‐containing waste which must be discharged. This fact, is largely responsible for the demise of U.S. synthetic plants. The natural soda ash processes produce no large volumes of associated wastes. By‐products and coproducts include calcium chloride, ammonium chloride, sodium bicarbonate, and sodium hydroxide.