Sodium hydroxide, also known as caustic soda or lye, is an ingredient occasionally used in the production of laundry detergents. It is a strong alkaline compound that is corrosive in its raw form, and should only be used with care in products when formulated to be safe and non-irritating.

In laundry detergents, sodium hydroxide is primarily used as a pH adjuster or neutralising agent. It helps to balance the acidity or alkalinity of the detergent formulation, ensuring that it falls within the desired pH range for optimal performance. Maintaining the appropriate pH level is essential for the detergent's effectiveness in removing dirt, stains, and odours from fabrics.

It's important to note that while sodium hydroxide is used during the manufacturing process of some laundry detergents, it is not typically present in the final product in significant amounts. Appropriate care should be taken by workers to ensure safe handling of raw materials. Through proper formulation and quality control measures, manufacturers are able to ensure that the sodium hydroxide is thoroughly reacted and neutralized during production, in compliance with relevant safety regulations and best practice, resulting in a safe and effective laundry detergent for consumer use.

Regarding its environmental impact to waterways, a 2007 EU risk assessment of sodium hydroxide in consumer products concluded that it's effectively neutralised in waste waters and there is “no need for risk reduction measures beyond those which are being applied already.”

Other names: Caustic Soda, Lye, natrii hydroxidum

Chemical class: Inorganic bases

REFERENCES

European Chemicals Bureau. (2007). European Union Risk Assessment Report: Sodium Hydroxide. https://echa.europa.eu/documents/10162/0ded9c53-4082-405b-b09a-e16e57e158af

National Center for Biotechnology Information (2023). PubChem Compound Summary for CID 14798, Sodium Hydroxide. https://pubchem.ncbi.nlm.nih.gov/compound/Sodium-Hydroxide