A criterion for judging the purity of adsorbed surfactant layers

Influence of Surface-Active Trace Impurities on the Surface Properties of Aqueous Solutions of Oligoethylene Glycol Monooctyl Ethers

“…1. With rising number j of purification cycles the equilibrium surface tension e increases successively until a constant plateau value is reached indicating the absence of surface active impurities from the surface layer (12). This plateau value clearly shows that the main component is not impoverished during the purification process.…”

“…The shift of the isotherm of the surface-chemically pure solutions toward higher surface tension values at fixed concentrations is characteristic of such a procedure (1,12). The isotherms of the surface chemical pure solutions can be described by the approach to a surface equation of state of Lunkenheimer and Hirte (13,14).…”

The effect of the removal of trace impurities on the adsorption behavior of octanoic acid at mercury–solution and at air–solution interfaces

“…Their removal results in a faster achievement of the equilibrium state. Phenomena like this are meanwhile well known for the airwater interface [11,20].…”

Phase Transition in an Adsorption Layer of a Soluble Surfactant at the Air–Water Interface

“…This behavior was first recognized by Elworthy and Mysels (22) and a purification scheme using foam fractionation was proposed (23). Lunkenheimer and co-workers dedicated a lot of their research to the nature and impact of these trace impurities on interfacial behavior (24)(25)(26). His studies provide experimental evidence that the above-mentioned features are only caused by highly surfaceactive impurities, with dodecanol as the major trace impurity in the case of SDS and octanoic acid in the case of sodium octanoate.…”