The effect of surfactant structure on the rate of oil solubilization into aqueous surfactant solutions

Abstract

Reduced washing temperatures decrease the rate of the various processes in a laundry cleaning cycle. This implies that fast acting detergents are needed if acceptable washing performance is to be maintained within a realistic period of time. An important factor is the rate of oily soil removal which, among other things, is a function of the molecular structure of the surfactants used in the detergent. To support the selection of proper surfactants we have established relationships between chemical structure and rate ofoil solubilization for a series of alkylarenesulfonates with various alkyl chain lengths, points of attachment of the phenyl group at the alkyl chain, and aromatic substitution patterns. It is shown that oil solubilization kinetics are very sensitive to the geometry of the surfactant structure: for a set of isomeric alkylarenesulfonates the rate of oil solubilization can be made to vary by more than an order of magnitude by changing the substitution pattern around the aromatic ring. The results offer a predictive tool for the design of molecules with the proper surface activity under a wide set of experimental conditions.Reduced washing temperatures slow down the various processes involved in the laundry cleaning process. Adjustments of the composition and nature of the surfactant components in laundry products may have to be considered to maintain satisfactory washing performance within a reasonable period of time. An important kinetic aspect of the washing process is the rate of removal of oily stains.Several mechanisms have been proposed for the solubilization of oils into micelles. One mechanism involves dissolution of the solubilizate into the aqueous phase, followed by adsorption onto the micellar surface and subsequent incorporation. This mechanism is advocated by Kahlweit (1), Volkov (2), Arytyunyan (3) and Schwuger (4), although each favors a different step as the rate-limiting one. A second mechanism in essence consists of diffusion of the micelle toward the oil droplet, followed by demicellization, adsorption of monomeric surfactant molecules onto the oil/water interface, incorporation of solubilizate and desorption of the "swollen" micelle. Chan (5) and Carroll (6) support this mechanism. The difference in views about the mechanism of solubilization is not in the least caused by the use of different solubilizates and surfactants. Even more complicated to interpret are data obtained in the presence of a third (solid) phase such as fabrics (7), polyester films (8,9) or aluminum foil (10).This work deals with the relationship between surfactant structure and rate of oil solubilization, using anionic alkylarenesulfonates. The emphasis will be 1Presented at the joint AOCS-Japan Oil Chemists' Society meeting in Honolulu, Hawaii, in May 1986. *To whom correspondence should be addressed. put on phenyl positioning, aromatic substitution pattern and alkyl chain length of the surfactant. Furthermore, the effects of external experimental parameters such as temperature and concentrations will be disc...

Interfacial Mass Transfer in Trichloroethylene/Surfactants/ Water Systems: Implications for Remediation Strategies

“…In other words, when the surfactants are present at high concentrations, the aggregates they form in solution are larger and can dissolve more TCE molecules, but, as a drawback, move slower into the bulk. Such a limitation was pointed out by several authors that found the aqueous micellar diffusion to be potential rate-limiting steps in interphase mass transfer [41][42][43][44]. In the case of SYN91/5, we could confirm a slowing effect of the micelles by comparing the TCE diffusion coefficients in pure water at 25 • C (D = 8.16 × 10 −6 cm 2 s −1 [5]) with the diffusivity of SYN91/5 found to be in the range of ∼5 × 10 −7 -∼2 × 10 −6 cm 2 s −1 at 25 • C (0.01 < [SYN91/5] < 0.1 M) [45].…”

Efecto de los surfactantes sobre la absorción de agroquímicos en plantas

“…El ajuste de la composición y naturaleza de los componentes de los surfactantes conduce a la versatilidad del mismo cuando se aplican agroquímicos (Bolsman et al, 1988).…”

“…Además de la carga (aniónica o catiónica) como el principal factor que incide en la eficiencia de la aplicación de agroquímicos complementados con surfactantes o tensoactivos (Bolsman et al, 1988).…”

“…A nivel estructural se ha demostrado que dicho factor incide directamente sobre la eficiencia de disolución de las fases sobre todo en compuestos de alta viscosidad (Bolsman et al, 1988). Desde el punto de vista ambiental, la temperatura y humedad relativa del medio influyen directamente sobre la funcionalidad de los surfactantes, ya que algunos solidifican a valores bajos de estas condiciones.…”

Surfactant‐enhanced remediation of DNAPL zones in granular aquifer systems

“…Priddle (1992) and Edwards et al (1992) have shown that solubilization of creosote and coal tar liquids is also practical with nonionic su rfactants. The potential mechanisms and kinetics of solubilization were reviewed by Bolsman et al (1988). One involves the dissolution of oil (i.e., DNAPL) molecules into the aqueous surfactant solution (surfactant-amended groundwater), whereas the more recent (Carroll, 1981) involves the dissociation of surfactant micelles at the DNAPL/water interface, the subsequent adsorption of the surfactant monomers, and then the desorption of the reformed micelle with the incorporated DNAPL molecule back into aqueous solution, as shown in Figure 2.…”