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What is sodium hydroxide used for in petroleum refining and soapmaking?

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Sodium hydroxide (NaOH) serves critical roles in both petroleum refining and soapmaking due to its properties as a strong industrial alkali.

Petroleum Refining

In the refining process, sodium hydroxide is used to remove acidic impurities from oil. It is employed to neutralize and extract sulfuric acid and various organic acids. Additionally, it is used to pretreat oil to remove traces of hydrogen sulfide and alkyl phenols. When combined with specific solutizers, it can also increase the solubility of higher mercaptans, facilitating their extraction from fuel to reduce total sulfur content.12

Soapmaking

Sodium hydroxide is essential to the process of saponification, which is the fundamental chemical reaction used to create soap. During this process, sodium hydroxide reacts with natural fats or oils—such as tallow or vegetable oil—to produce glycerin and sodium fatty acid salts, which constitute the final soap product.1