Sulfonated methyl esters, linear alkylbenzene sulfonates and their mixed solutions: Micellization and effect of Ca2+ ions

Abstract

Here, we compare the properties of sulfonated methyl esters of fatty acids (SME) and linear alkylbenzene sulfonate (LAS) with respect to the effect of calcium ions on their surface tension and the effect of their mixing on the critical micelle concentration (CMC). The theoretical interpretation of surface tension isotherms obtained in the presence of NaCl and CaCl 2 allowed us to determine the parameters that characterize the surfactant adsorption layers and counterion binding. The excluded area per molecule in the adsorption layer is the same for SME and LAS, and is determined by the cross-sectional area of the sulfonate headgroup. The binding energy of Na + ions to the headgroups of SME and LAS is also the same. However, the binding energy of the Ca 2+ ion to the headgroup of LAS is considerably greater than that of SME in agreement with the circumstance that LAS is precipitated by hard water. In contrast, the binding energy of the Ca 2+ ion to the headgroup of SME is lower even than that of Na + , in accord with the reputation of SME as one of the most hard-water tolerant surfactants. The dependencies of the CMC on the composition of binary mixed surfactant solutions reveal that C14-SME and C16-SME exhibit ideal mixing; C14-SME and LASslightly synergistic mixing, whereas C16-SME and LAS -antagonistic mixing due to hydrocarbon-chain mismatch. The micellization in mixed solutions of SME and cocamidopropyl betaine has been also investigated. The results in the present study allow prediction of the surface tension of solutions of SME and LAS in the presence of Na + and Ca 2+ ions at various concentrations; contribute for a better understanding of the different tolerance of SME and LAS to hard water, and quantify the effect of their mixing on the CMC.

Cleaning Ability of Mixed Solutions of Sulfonated Fatty Acid Methyl Esters

“…The addition of 5 mM Ca 2+ decreases σ AW with 1–2 mN m −1 . The effect is stronger for SLES as compared to C16‐SME, in agreement with the finding for relatively low binding energy of the Ca 2+ ions to the sulfonate groups of SME (Ivanova et al, ). The lowering of σ AW with 7–9 mN m −1 due to DDAO is a much stronger effect than that of 5 mM Ca 2+ .…”

“…SME are derived from renewable sources and are considered as a green alternative of petroleum‐derived surfactants (Jin et al, ; Lim et al, , ; Maurad et al, ; Siwayanan et al, ; Xu et al, ). SME are insensitive to the water hardness, unlike the linear alkylbenzene sulfonates (LAS), which are widely used in cleaning formulations (Cohen and Trujillo, ; Ivanova et al, ; Lim et al, , ; Xu et al, ). Mixtures of SME and LAS have been shown to improve the LAS solubility in hard water and have been used to achieve significant builder's reduction in detergent formulations (Lim et al, ).…”

“…Along with the detergency characterization, there is a considerable advance in the physicochemical characterization and theoretical modeling of adsorption and micellization of the different SME and their mixtures with other ionic or nonionic surfactants (Basheva et al, ; Danov et al, ; Ivanova et al, ; Patil et al, ; Wang et al, ; Wong et al, ; Xu et al, ).…”

Rheology of mixed solutions of sulfonated methyl esters and betaine in relation to the growth of giant micelles and shampoo applications

“…Here, they will be denoted C n SME, n = 12, 14, 16, 18. Information for the adsorption and micellar properties of C n SME can be found in Refs. [70][71][72]. So far, there is a single study on the rheology of micellar SME solutions without cosurfactants (like CAPB) and thickeners, but in the presence of nanoparticles [73].…”

Methyl Ester Sulfonate: A High‐Performance Surfactant Capable of Reducing Builders Dosage in Detergents

“…A previous foamability and Krafft temperature study has shown that α‐MES has excellent tolerance toward water hardness (Lim et al, ). To better understand the tolerance of α‐MES to hard water, Ivanova et al characterized the binding energy of Ca 2+ ions to the headgroups of α‐MES by means of theoretical modeling (Ivanova et al, ). The study showed that the binding energy of the Ca 2+ ions (2.39 К T) to the headgroup of α‐MES is smaller than that of Na + (2.91 К T), which helps explain the superiority of α‐MES under challenging conditions.…”