Sodium C14-16 Olefin Sulfonate (SCOS or AOS) is a widely used surfactant in consumer goods, functioning primarily as a cleansing agent and foaming booster. Manufacturers value it for its effective detergency and ability to produce a rich, stable lather, even in hard water conditions. As a surfactant, it is responsible for the cleaning action in many liquid formulations.
Chemical Identity and Function
Sodium C14-16 Olefin Sulfonate is classified as an anionic surfactant, meaning the hydrophilic (water-loving) head of the molecule carries a negative charge. This characteristic allows it to interact effectively with and suspend dirt and oil. The SCOS molecule consists of a long hydrocarbon chain, a sulfonate group, and a sodium ion.
The “C14-16” in the name indicates the hydrocarbon chain length, which is a mixture primarily containing 14 to 16 carbon atoms. This range balances solubility with cleansing strength, contributing to its optimal performance.
Surfactants function by lowering the surface tension between substances like oil and water. SCOS is bipolar, having a water-loving head and an oil-loving (hydrophobic) tail. When mixed with water, these molecules form spherical structures called micelles. The hydrophobic tails trap grease and dirt inside the micelle, while the hydrophilic heads face outward, allowing the encapsulated dirt to be rinsed away easily.
The sulfonate group, where the sulfur atom bonds directly to a carbon atom, distinguishes SCOS from true sulfates like Sodium Lauryl Sulfate (SLS). This chemical difference enhances the molecule’s stability and allows SCOS to maintain effectiveness across a broad pH range, making it a versatile component in many formulations.
Common Applications in Consumer Products
SCOS is popular across consumer and industrial products due to its potent cleansing and foaming capabilities. Its primary use is in personal care items designed to be rinsed off, such as shampoos, body washes, facial cleansers, and bubble bath liquids, where stable foam is highly desirable.
SCOS is also incorporated into household cleaning products, including dishwashing liquids, laundry detergents, and all-purpose cleaners. Manufacturers often select this ingredient because it performs well in hard water conditions, being less susceptible to mineral inactivation than many other surfactants.
The ingredient is frequently chosen as a high-performance alternative in products marketed as “sulfate-free.” SCOS provides a strong cleansing action and rich lather similar to traditional sulfates, but its distinct chemical classification allows it to meet this marketing standard.
Manufacturing Source and Process
The production of SCOS begins with alpha-olefins, which are long-chain hydrocarbons. These raw materials can be sourced from petrochemicals (cracking of petroleum) or derived from natural sources, such as processing fatty acids from coconut or palm oils.
The process involves a chemical transformation called sulfonation. The C14-C16 alpha-olefins are reacted with sulfur trioxide gas, which chemically modifies the olefin molecule by adding the sulfonate group.
The resulting acidic mixture is then neutralized using a sodium source, such as sodium hydroxide or sodium carbonate, to create the final sulfonate salt. This process yields a mixture of sodium alkene sulfonates and sodium hydroxy alkane sulfonates. Although the starting material may be naturally derived, the final ingredient is a chemically processed compound.
Safety Profile and Environmental Considerations
The safety of SCOS has been evaluated by independent scientific bodies, such as the Cosmetic Ingredient Review (CIR) Expert Panel. The panel concluded that SCOS is safe for use in products designed to be rinsed off the skin and hair, based on its history of use and generally low toxicity profile.
Skin sensitivity concerns are primarily linked to the ingredient’s concentration. Although SCOS is often considered milder than older surfactants, it remains a powerful cleansing agent that can cause irritation, especially to the eyes or sensitive skin, when used above five to ten percent concentration. Products must also meet strict limits on trace impurities, such as gamma sultones, which are potential sensitizers.
SCOS is often confused with sulfates (like SLS or SLES) due to its name. However, SCOS is a sulfonate, meaning the sulfur atom bonds directly to a carbon atom, unlike a true sulfate which bonds through an oxygen atom. This structural difference contributes to SCOS being more stable and generally less irritating than many traditional sulfates.
From an environmental standpoint, SCOS is considered readily biodegradable. It breaks down quickly once it enters the wastewater system. This rapid degradation, combined with its low measured aquatic toxicity, minimizes its potential for long-term ecological impact in waterways.