Linear Alkyl Sulfonate (LAS)

Definition - What does Linear Alkyl Sulfonate (LAS) mean?

Linear alkyl sulfonate (LAS) is an anionic surfactant widely used in detergents and cleaners, both in industrial and household applications. This term is applied to a family of straight-chain chemical compounds, sometimes called "soft" detergents. The linear alkyl chain of the LAS makes the molecule more biodegradable than branched alkyl benzene sulfonates.

LAS is found in waste water. It is claimed that it acts as a corrosion inhibitor for stainless steel and aluminum.

Linear alkyl sulfonate is also known as linear alkylbenzene sulfonate.

Corrosionpedia explains Linear Alkyl Sulfonate (LAS)

Linear alkyl sulfonate lowers the surface tension of water, enabling soils and stains to loosen and release from fabrics and surfaces. It is a readily biodegradable replacement for highly branched alkylbenzene sulfonates (ABS).

LAS has a good ability to remove and keep particles in dispersion. This is utilized in detergents for textiles to remove inorganic dirt. The alkyl chain of the molecule adheres to the solid surface that mostly has a faint negative charge. LAS is stable against oxidation, making it suitable to use in mixtures containing oxidants like bleaching agents. It does not work well in hard water where water-insoluble calcium soaps are precipitated. This is compensated by using it in mixtures together with softening substances and other surfactants. In oil-based systems the calcium salts of LAS keep wear and soot particles in dispersion and they are therefore used in motor oil to prevent deposits in the motor.

About 85% of LAS is used in household detergents, such as:

  • Laundry powders
  • Laundry liquids
  • Dishwashing liquids
  • Other household cleaners

Industrial, institutional and commercial detergents account for most of the other applications of LAS, but it is also used as an emulsifier and wetting agent. LAS can be used in metal cleaning to remove corrosion rust.

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