Apparatus for programmed high-performance purification of surfactant solutions

Abstract

Generally, surfactants contain trace impurities that will falsify their adsorption properties enormously. To carry out reliable experiments with surfactant solutions necessitates removing those trace impurities beforehand. A programmed apparatus for removing surface-active trace impurities from surfactant solutions has been constructed and tested. It takes advantage of the contaminants’ stronger surface activity and considerably lower content in comparison with the main surfactant component. Surface-active material of the solution to be purified is allowed to adsorb at its surface. After considerable reduction of the solution surface area, the adsorbed material is sucked off from the surface in a definite manner by using a fine capillary. The single operating steps are repeated periodically and automatically until the solution reaches the state of ‘‘surface chemical purity.’’ The apparatus can be utilized for a wide range of different conditions given by the individual surfactant properties simply by changing the operating parameters. The instrument favorably and effectively provides that peculiar grade of surfactant purity necessary for all kinds of fundamental surfactant research and characterization.

Interfacial Behavior of n-Decyl-β-D-maltopyranoside on Hydrophobic Interfaces and the Effect of Small Amounts of Surface-Active Impurities

“…The high-performance surfactant purification apparatus used in this work has been described in detail elsewhere (3). Basically, the surfactant solution is equilibrated with a large air-liquid interface that subsequently is compressed and aspirated.…”

“…From the above it is clear that the accurate determination of equilibrium surface properties of surfactant solutions requires very pure samples. Over the years this has inspired the development of various surfactant purification systems such as foam fractionation (1,2) and the Lunkenheimer purification system (3).…”

On the Internal Structure of an Adsorption Layer of an Ionic Soluble Surfactant. The Buildup of a Stern Layer Monitored by Optical Means

“…An aqueous solution of the surfactant at a concentration close to the critical micelle concentration was prepared using bidistilled water. This solution was then purified using a fully automated device described in ref 24. The applied purification scheme ensures a complete removal of any surface active impurities by repeated cycles of (a) compression of the surface layer, (b) its removal with the aid of a capillary, (c) dilation to an increased surface area, and (d) again a formation of a new adsorption layer.…”

Effect of the Supporting Electrolyte on the Adsorption of Octanoic Acid at the Mercury/Electrolyte Interface

“…A less than 10% decrease of the capacitance was observed after 500 s for a 0.1 M KCl, at potentials close to pzc. A 3.5 × 10 −3 M stock solution of octanoic acid was purified using the apparatus described in (26). The traces of existing highly surface-active impurities were removed by aspirating the adsorption layer of stock solution repeatedly.…”