Role of Surfactant-Adsorbent Acidity and Solvent Polarity in Adsorption-Desorption of Surfactants from Nonaqueous Media

Abstract

Adsorption of surfactants at the solid-liquid interface is governed in general by the properties of the surfactant, solid, and solvent. However, very little is known about the role of these properties in the case of adsorption from organic media. In this study the effect of adsorbent and surfactant acidities and solvent polarity on the adsorption of surfactants on oxide minerals in nonaqueous solvents has been investigated.The studies conducted using anionic (Aerosol OT) and cationic (dimethyldodecylamine) surfactants on the basic and acidic oxide minerals (alumina and silica) reveal that for a given surfactant the polarity differential between the adsorbent and the solvent is responsible for the partitioning of the solute to the solid-liquid interface. Following this, acid-base-type interactions between the solute and the adsorbent can take place to enhance the attachment of the former to the particles. The acid-base interactions depend on the nature of the surfactant and the substrate, with an acidic surfactant interacting strongly with a basic adsorbent and vice versa. By using the solvent dielectric constant as an indicator of solvent polarity, it was found that while polar interactions control the adsorption from solvents of low polarity, hydrocarbon chain interactions with the surface play a major role in determining adsorption from solvents of higher polarity.

On the Behavior of Micellar Solutions in Tangential Ultrafiltration Using Mineral Membranes

“…This temperature is too alumina for Tami. The former is obviously hydrophobic and far away from the temperature of the reported experiments may interact with the alkyl chain of the surfactant, whereas (room temperature) for invoking any kind of phenomenon the latter (which will not be considered in this discussion) related to micellar growth when the critical temperature is may interact with the polar heads (19,20). In the case of approached.…”

Simple Colloids in Simple Environments Explored in the Past, Complex Nanoids in Dynamic Systems to be Conquered Next: Some Enigmas, Challenges, and Strategies

“…In a study of the adsorption of surfactants on alumina from cyclohexane, the cationic surfactant/dimethyl dodecylamine was found to adsorb more on acidic surfaces, whereas the anionic Aerosol OT adsorbed on basic surfaces, suggesting that adsorption probably occurs through interactions between the polar groups on the surfactant and the solid ( Fig. 5) (34). Increase in the solvent polarity caused a decrease in adsorption.…”

A new model to describe the sorption of surfactants on solids in non-aqueous media

“…A series of surfactant adsorption/desorption data published previously [20,21] was used to test the validity of this approach.…”