Influence of Long-Chain Alcohols on the Adsorption of Nonionic Surfactants to Silica

Abstract

The adsorption of surfactant-alcohol mixtures at the silica-water interface was studied by means of ellipsometry. The results show that addition of even small amounts of alcohol can have large effects on the characteristics of the adsorbed layer. For example, a 20% replacement of the octa(ethylene glycol) dodecyl (C12E8) surfactants by dodecanol results in an increase in the total surface excess of 80%. The thickness of the adsorbed layer, on the other hand, is virtually unaffected by the alcohol being added. Hence, as the alcohol content increases, the adsorbed surfactant aggregates at the silica-water interface mainly grow in the surface plane. A surfactant such as C12E5, which forms relatively large surface aggregates from the start, can only solubilize a small fraction of the long-chain alcohols before the system phase separates. This fraction was found not to result in any major structural changes in the surface layer. These findings are discussed in terms of surfactant packing and in relation to observations in bulk solutions reported earlier. Our study also includes measurements of adsorption and desorption kinetics for both the surfactant and the surfactant-alcohol systems. The main finding is that the effect of alcohol is most obvious in the desorption kinetics. We conclude that the effects observed are due to differences between the surfactant and the alcohol in monomer solubility.

Desorption kinetics of polycyclic aromatic hydrocarbons (PAHs) from contaminated soil and the effect of biosurfactant supplementation on the rapidly desorbing fractions

“…The lower desorption rate of PYR (48%) compared to PHE (71%) can be explained by the more hydrophobic nature of PYR, which can be reflected by the higher octanol/water partition coefficient (Log K ow ) of PYR. These results are in accordance with similar ones [47,48] showing greater affinities for a specific sorbent for more hydrophobic PAHs.…”

“…All desorption kinetics curves were indeed observed to include an initial rapid desorption phase followed by slow desorption rates (Figures 2 and 3). The amount of PAHs desorbed from the soil increased as the concentration of biosurfactant in the solution and the equilibration time increased, as previously reported [47,50].…”

Heterogemini Surfactants Based on Fatty Acid Synthesis and Interfacial Properties

“…Schematic representation of the heterogemini surfactants and comparisons to conventional, linear, ethylene-oxide based-surfactants or mixtures of ethylene oxide surfactants, and long-chain alcohols. C 10 OH is added to C 12 E 8 in a 1 : 1 molar ratio (31). Addition of C 9 OH to C 9 E 11 should have a similar effect.…”

Adsorption of Ethoxylated Nonionic Surfactants From Siloxane-Based Solvent and Aqueous Systems: Use of QCM and Model Polymeric Surfaces

“…Most of these applications involve adsorption of the surfactants from their solutions onto various interfaces. Studies have been conducted to understand the adsorption behavior of the surfactants at various interfaces in aqueous environment (Blom et al, 2005;Brinck et al, 1999;Cai et al, 2003;Caruso et al, 1995;Desbene et al, 1997;Geffroy et al, 2000;Gilchrist et al, 2000;Grant et al, 2000;Kharitonova et al, 2005;Kjellin et al, 2002;Kumar and Tilton, 2004;Lindheimer et al, 1990;Portet et al, 1996;Somasundaran et al, 1991;Tahani et al, 1996;Thirtle et al, 1997;Torn et al, 2005). Parameters governing the adsorption behavior include morphology and chemistry of solid surface, functional groups involved, solute-solvent interactions, intermolecular forces between adsorbed molecules, pH, and temperature.…”

“…Characteristics of the adsorption process were studied using various techniques like fluorescence decay (Levitz and Van Damme, 1986), calorimetry (Lindheimer et al, 1990;Denoyel and Rouquerol, 1991), neutron reflection (Thirtle et al, 1997;Lee at al., 1989), ellipsometry (Gilchrist et al, 2000;Kjellin et al, 2002;Stalgren et al, 2002;Tiberg et al, 1994), surface plasmon resonance (Caruso et al, 1995), quartz crystal microbalance (Caruso et al, 1995;Stalgren et al, 2002), high-performance liquid chromatography (Desbene et al, 1997;Portet et al, 1996), and gravimetry (Caruso et al, 1996). Silica-water interface is the most studied surface for ethoxylated surfactant adsorption (Blom et al, 2005;Brinck et al, 1999;Desbene et al, 1997;Kharitonova et al, 2005;Kjellin et al, 2002;Portet et al, 1996;Thirtle et al, 1997;Stalgren et al, 2002).…”