Alkylbenzene sulphonates

Alkylbenzene sulphonates belong to the group of anionic surfactants. They are formed by sulfonation of alkylbenzene, usually containing a linear chain of 10-13 carbon atoms. As a result, alkylbenzene sulphonic acid (ABS acid) is obtained. In the next stage, it is neutralized with sodium hydroxide, which results in obtaining alkylbenzene sulphonic acid sodium salt. The sulfonating agent may be oleum i.e. a mixture of sulphuric acid and sulphur trioxide, sulphur trioxide gas, or chlorosulphonic acid.

In this group of compounds, the remaining sulphone is a hydrophilic group, while the alkylbenzene chain is hydrophobic. The representative of this group of anionic surfactants produced in the largest quantities is sodium dodecylbenzene sulphonate, i.e. ABSNa.

Physico-chemical properties

Alkylbenzene sulphonates containing linear alkyl chain in their structure are much more biodegradable compared to their branched equivalents. Products obtained in the reaction with alkylbenzene containing a longer carbon chain have better surface-active properties, but are less soluble in water. ABS in the form of acid usually has a very high concentration of the active substance – between 96 and 98%, while its sodium salts have active substance concentration ranging from 30 to 75%.

Alkylbenzene sulphonates are well soluble in water. They exhibit detergent and wetting properties and have the ability to form high and dense foam. They are stable in mixtures with all non-ionic and amphoteric surfactants, but are not compatible with cationic compounds and enzymes.

Application

Alkylbenzene sulphonates are widely used in the production of washing powders and liquids as well as cleaning and washing preparations. Due to their strong degreasing properties, they are not used in the formulas of shampoos and body wash products. They are adopted in industrial processes, such as emulsion polymerization and production of plant protection products.