Interaction of Anionic Detergents and Certain Polar Aliphatic Compounds in Foams and Micelles

Abstract

The addition of non-ionic surface active compounds to solutions of a variety of anionic detergents has been shown to enhance foam stability. The effectiveness of such compounds depends strongly on the detergent. It is found that detergents increase in "susceptibility to foam stabilization" in the order (1) branched alkylbenzene sulfonates, (2) n-alkylbenzene sulfonates, (3) secondary alkyl sulfates, (4) 2-re-alkane sulfonates and (5) primary alkyl sulfates. This is also the order of increasing surface tension of the detergents (without additives) at concentrations greater than the critical micelle concentration (CMC). The polar aliphatic additives with straight hydrocarbon chains of 8-14 carbon atoms were the more effective foam-stabilizers and among these effectiveness increased in the order (1) primary alcohols, (2) glycerol ethers, (3) sulfolanyl ethers, (4) amides, and (5) N-polar substituted amides. This order is, in general, the order of increasing surface activity and CMC-depressing activity. Monolayer compositions calculated from surface tension and CMC measurements show that in the mixed monolayer there is negligible specific interaction between detergent and additive molecules, and that increasing foam stability in a series of detergent-additive pairs corresponds to an increasing mole fraction of additive in the adsorbed monolayer. The most stable foams were found with detergent-additive pairs having 60-90% of additive in the adsorbed monolayers. The requirements for preferential adsorption of additives are the same as found for foam stability: solutions of the detergent (without additive) should have a high surface tension, the additive should give water a low surface tension, and should depress the CMC of the detergent. The mechanism of CMC depression by additives is discussed, and the importance of the distribution of additive between sites on the surface of a micelle and elsewhere in a detergent solution is pointed out.

INFRARED EXTINCTION COEFFICIENTS OF KETONES ADSORBED ON Ca-MONTMORILLONITE IN RELATION TO SURFACE COVERAGE. CLAY-ORGANIC STUDIES. PART IV1

“…The structure of Y-(OH)316 shows yttrium in the center of a regular trigonal prism with oxygen in the six corners and three more oxygens adjacent to the lateral faces of the prism. Assuming the radius of F~to be 1.36 A., 13 the radius ratio for Y+3 to F_ is 0.70, which is close to the minimum radius ratio of 0.732 proposed by Pauling17 for coordination numbers 8 or 9. The crystal structures of YF3 and Y (OH)3 indicate that a coordination number of 9 exists even though the minimum radius ratio has not been satisfied.…”

Ideal Two-Dimensional Solutions. Ii. A New Isotherm for Soluble and “Gaseous” Monolayers

“…However, this equation is of little value for finite values of t. For protein monolayers Bull9 and others10 have used the substitution Nm/M = nx (where N is Avogadro's number, m the mass of material spread on surface area A, and M the molecular weight) to give ttA mRT M ~ ( -v2)(approx.) (7) A graph of irA vs.…”

Foaming and Antifoaming by Aqueous Solutions of Surfactants

“…The order of susceptibility to foam stabilization is as follows: primary alkyl sulfates > 2-n-alkanesulfonates > secondary alkyl sulfates > n-alkylbenzene-sulfonates > branched-chain alkylbenzenesulfonates (Sawyer, 1958). This is exactly the order of decreasing van der Waals interaction with an adjacent compound containing a straight-chain hydrocarbon group.…”

“…It has been found (Sawyer, 1958) that the order of effectiveness in these additives is N-polar substituted amides > unsubstituted amides > sulfolanyl ethers > glycerol ethers > primary alcohols. This order may be that of decreasing ability to form hydrogen bonds with the adjacent surfactant and water molecules since film viscosity increases greatly where hydrogen bonding between adjacent molecules is possible.…”