Investigations on the possibility of purifying surfactant solutions by adsorption on solids

Abstract

Abstract:Originating from a known purification procedure for the fluid-gaseous boundary a technique for a definite purification of surfactant solution is presented using solid adsorbents. The capability of the procedure is demonstrated using various surfactants and different adsorbents. It is applicable at concentrations below as well as above the CMC.

Surface Properties of Alkylpyridinium Chlorides and the Applicability of the Pendant Drop Technique

“…For C 18 we estimate t e Ϸ 3 h. Table 2 shows that there are three isotherms that just fail to fulfill the condition of Eq. [17] but fulfill the condition of Eq. [14]: C 14 /0.1 mol liter Ϫ1 KCl, C 16 /0.01 mol liter Ϫ1 KCl, and C 18 /no KCl.…”

“…The surfactants were analyzed with respect to water content, melting point, chain length, purity, and counterion purity by HPLC, NMR, and TGA/DSC (15,16). All surfactants (except octadecylpyridinium chloride) were highly purified at the Max Planck Institute of Colloids and Surfaces, Berlin, Germany, by employing the Lunkenheimer method (17,18). Due to its high surface activity, octadecylpyridinium chloride cannot be purified by this method and was used in the recrystallized form.…”

“…[9] and [5] ⌬x c Х⌫ CMC Ͻ 0.025 mm, [16] and, instead of Eq. [14], CMC Ն 1.76 ϫ 10 Ϫ4 mol liter Ϫ1 , [17] which is 10 times less than in case a. According to Eq.…”

“…Although the surfactant was cleaned using the Lunkenheimer method (see above), the grade "surface-chemically pure" (a term used by Lunkenheimer to characterize purity) could not be achieved within a reasonable number of cleaning cycles. In principle, the method is capable of producing surfactants of highest purity as long as certain conditions are fulfilled [see (17,18) for details]. Investigations on the chemical nature of these impurities (15) show that they are mainly long-chain homologues with much higher surface activity.…”

The Preparation of Surface Chemically Pure Sodiumn-Dodecyl Sulfate by Foam Fractionation

“…With this in mind it is crucial that any SDS solutions are used as rapidly as possible CONCLUSIONS after production and that any and all steps possible are taken to avoid contamination. Recent efforts to prepare exceptionally pure SDS have tended to concentrate on in situ methods (3,6) which are limited in application to solutions of the pure single surfac- the current work has been to provide for this.…”