Sorption and desorption of alcohol sulfate surfactants in an agricultural soil.

Alcohol sulfates are one of the most important types of commercial anionic surfactants and may pose serious environmental problems. The present study examines the sorption behavior of alcohol sulfates in an agricultural soil using a batch reactor and column experiments. Kinetics and equilibrium isotherms of the sorption and desorption processes of the following alcohol sulfate homologues have been determined: AS-C12, AS-C14, AS-C16 , and AS-C18. Sorption and desorption occurred rapidly, and equilibrium was achieved in approximately 1 h. The sorbed mass percentages were 35.1% AS-C12 , 67.2% AS-C14 , and 100% for both AS-C16 and AS-C18. A pseudo-first-order kinetic model provided an adequate fit of data. Sorption and desorption equilibrium data were fitted into 1) a linear model, with r(2) values in the ranges 0.712 to 0.988 and 0.736 to 0.983, respectively, and 2) a Freundlich model, with r(2) values in the ranges 0.956 to 0.991 and 0.891 to 0.981, respectively. Continuous-flow experiments in soil columns were carried out to obtain the breakthrough curves for each compound. The present study provides basic theoretical concepts and key parameters for developing mathematical models that simulate the migration of alcohol sulfate into agricultural soils.