Sodium hydroxide, also known as lye or caustic soda, was first discovered in the 18th century through the process of leaching plant ashes. Early production methods involved reacting soda ash with slaked lime in the Leblanc process to produce lye and calcium chloride. By the late 19th century, the membrane cell process was developed, allowing for cheaper and more efficient production of the chemical on an industrial scale. This electrochemical process involves passing brine through a membrane to separate ions and produce chlorine gas and lye as the primary products. Today, nearly all lye is produced using membrane cell technology due to its sustainability and economics compared to older production methods. Global annual production amounts to over 60 million tons currently.

Cleansing and Soap Manufacturing

One of the Sodium Hydroxide earliest and still major uses of lye is in soaps, cleansers and detergents. When mixed with animal or vegetable fats and oils, lye saponifies them, meaning it forms salts of fatty acids. These salts, known as soap, are able to dissolve grease, dirt and other unwanted substances when added to water. As a strongly alkaline substance, lye also functions as an excellent cleanser on its own in products like drain cleaners. An estimated 30-40% of annual lye production goes toward cleansing product manufacturing due to the chemical's unmatched ability to cut through and dissolve organic matter.

Paper Processing

The paper industry utilizes significant amounts of lye in the mechanical pulping process. Wood chips are treated with lye solutions at high temperatures, allowing the chemical to break lignin bonds between cellulose fibers. This converts wood into a pulp that can be further refined and processed into paper. Lye pulping produces a higher yield of usable fibers compared to older methods like groundwood pulping. Around 15% of annual lye production is dedicated to paper manufacturing worldwide. The chemical plays a key role in sustaining global paper production volumes.

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