Sorption of anionic surfactants SDS, AOT and cationic surfactant hyamine 1622 on natural soils

Sorption of anionic surfactants Aerosol-OT (AOT) and Sodium Dodecyl Sulfate (SDS), as well as cationic surfactant Hyamine 1622 on two soil surfaces were investigated. Batch equilibrium techniques were used under laboratory conditions to observe the amount of surfactant adsorbed and desorbed to and from the soil surfaces. Data obtained were fitted to two sorption isotherms in order to characterise the sorption process. The nature of the sorbate (i.e. the surfactant) was found to be important in the sorption process. Anionics adsorbed via hydrophobic bonding, whereas `cation-exchange' mechanism was dominant in the sorption of cationic Hyamine 1622. Anionic AOT, with a double chain, and hence a higher critical packing parameter, adsorbed more strongly onto the surface compared to the singly-chained SDS.