Examination of the adsorption of ethylene oxide–propylene oxide triblock copolymers to soil

The adsorption of 5 surfactants (P103, P105, F108, F127 and L92) to a sandy soil has been investigated. The surfactants are ABA block copolymers in which the A blocks are synthesised from ethylene oxide and the B block from propylene oxide. CMC values, for the block copolymers, as well as surfactant sorption to soil were measured by surface tension techniques. The adsorption of all five compounds can be described by the Freundlich adsorption isotherm. Adsorption, in each case, is related to the critical micelle concentration of the surfactant and the extent of adsorption appears to be linked also to the fraction of soil organic matter.