China 
Africa 
Explore chapters and articles related to this topic
Surfactant-Enhanced Aquifer Remediation: Fundamental Processes and Practical Applications
Published in Subhas K. Sikdar, Robert L. Irvine, Fundamentals and Applications, 2017
Kurt D. Pennell, Linda M. Abriola
Although the MSR has been widely used to characterize the solubility of HOCs in micellar solutions, relatively few studies have addressed the effects of organic properties and surfactant structure on the solubilization of environmentally relevant NAPLs. Based on MSR data, it has been shown that micellar solutions have a greater capacity to solubilize polarizable hydrocarbons, such as tetrachloroethylene (40,000 mg/l), than extremely hydrophobic compounds, such as dodecane (3500 mg/l) (Pennell et al., 1996b). These trends can be attributed to the fact that strongly hydrophobic organic compounds are solubilized almost entirely within the hydrophobic core of surfactant micelles. In contrast, polarizable hydrocarbons may be distributed throughout the hydrophilic mantle and the hydrophobic core (Mukerjee and Cardinel, 1978; Nagarajan et al., 1984). This difference in locus of solubilization results in the greater overall capacity of surfactants to solubilize polarizable hydrocarbons, although the relative magnitude of the solubility enhancement is likely to be greater for extremely hydrophobic compounds. To further investigate the locus of solubilization, Diallo et al. (1994) obtained MSR data for eleven NAPLs using a homologous series of dodecyl alcohol ethoxylates with HLBs ranging from 12 to 18. The authors were able to correlate a decrease in the solubilization of saturated hydrocarbons, such as dodecane, to the reduction in hydrophobic core volume. These findings indicate that it is possible to relate the solubilization behavior of a particular surfactant to changes in the size and structure of surfactant micelles.
Scattering from Wormlike Micelles
Published in Raoul Zana, Eric W. Kaler, Giant Micelles, 2007
Jan Skov Pedersen, Luigi Cannavacciuolo, Peter Schurtenberger
Surfactants in solution exhibit a complex aggregation behavior as a result of a delicate balance of opposing forces.24 Micellar solutions and microemulsions represent thermodynamically stable liquid dispersions containing surfactant aggregates, which can often be found in a large region of the phase diagram of two- or multicomponent surfactant systems.25-27 The relation between microstructure and phase equilibria is an important aspect of surfactant systems. Several theoretical concepts based either on packing considerations of the surfactants in the aggregates or on the role of the bending elastic energy of the surfactant monolayer have provided a theoretical framework for a better understanding of these systems.1,28-30 We can, for example, try to rationalize the morphology sequence and phase behavior of surfactant aggregates as being driven by the spontaneous curvature of the hydro-phobic/hydrophilic interface, H0. This quantity does not only depend on the space filling dimensions of the surfactant molecule, but may be tuned by various external factors such as the amount and nature of added electrolyte, the presence of other species in solution, the pH, or the temperature. For example, if the head groups are charged, they repel each other, which increases the effective head group area and favors the formation of small spherical micelles. The addition of electrolyte subsequently screens the electrostatic interactions, even more efficiently in the case of a strongly binding salt, which allow the head groups to approach each other closer and induces the formation of cylindrical structures. Similar arguments can be made for the known effect of temperature on nonionic surfactants of the CmEOn family, where temperature is known to change the spontaneous curvature of the surfactant due to the fact that water decreases its solvent quality with increasing temperature for the ethylene oxide head group. These ideas are developed further in Chapter 7 in regards to their implications for phase behavior.
Comparative solubilization of reactive dyes in single and mixed surfactants
Published in Journal of Dispersion Science and Technology, 2022
Sadia Noor, Muhammad Babar Taj, Senthilkumar M., Iram Naz
Surfactants are amphiphilic substances that facilitate the solubilization of additives and excipient molecules through a partitioning mechanism. These are useful products not only in nature but also in industries.[1,8,9] These molecules get adsorbed at the water–air interface even at very low concentrations and form self-aggregates (micelles). The micelle formation occurs on reaching a threshold level of concentration which is designated as critical micelle concentration (CMC). Quantification of this CMC can be estimated using various techniques: UV–Visible spectroscopy, conductometry, surface tension, and fluorometry.[10–16] The micelles are isotropic motifs of the surfactants having a hydrophilic head and a hydrophobic tail. Micellar solutions play a vital role in enhancing the solubility of less soluble or sparingly substances in aqueous media by the solubilization process.[17] Dye–surfactant aggregation provides useful insight into many industrial and chemical processes and also gives information about dye separation processes. Dye–surfactant interaction depends primarily on the nature and chemical structures of the participating dyes and surfactants.[16,18,19] The intermolecular forces which are dominant during such associations include hydrogen bonding, hydrophobic and electrostatic interactions, Van der Waals forces, and π-stacking.[20–23]
Prediction of the viscoelastic properties of a cetyl pyridinium chloride/sodium salicylate micellar solution: (I) characterization
Published in Petroleum Science and Technology, 2022
The surfactant solution is widely used in household and personal care products, and is also applicable in drag reduction, oil recovery, and solvent extraction (Pipe et al. 2010; Kinugasa et al. 2012; Jeirani et al. 2014; Zhao et al. 2014; Zhao, Haward, and Shen 2015; Xiong et al. 2018; Mpelwa et al. 2020). When the concentration of the surfactant increases to a certain level, micelles form, resulting in a micellar solution. Many of the solutions (Pipe et al. 2010; Zhao, Haward, and Shen 2015) exhibit the shear band phenomenon: the curve representing shear stress plotted against shear rate does not monotonically increase in the steady shear experiment and the shear stress approaches in a range of shear rate constantly. The viscoelastic property of the micellar solution, which exhibits the shear band phenomenon, influences flow behavior; this is in contrast with the fluid exhibiting a monotonic flow curve. The inhomogeneous flow in the solution is also thought to cause shear band behavior (Pipe et al. 2010).
Rheology study of wormlike micellar solution formed by 1-hexadecyl-3-methylimidazolium tetrafluoroborate ionic liquids in present of sodium salicylate
Published in Journal of Dispersion Science and Technology, 2021
Fang Wang, Zhiqing Zhang, Ying Wei, Ting Zhou, Xiufeng Wang, Guodong Zhang
It is well known that surfactant molecules in aqueous solution can self-assemble to form aggregates of diverse microstructures and shapes, such as micelles, vesicles, lyotropic liquid crystals and gels, etc.[1–6] In general, above the critical micelle concentration (CMC), surfactants usually form spherical micellar aggregates. Adding salts, the counterions can promote the spherical micells to grow enormously in geometry and form long and highly flexible aggregates, called wormlike micelles.[7–9] Because the counterions of salts interact with hydrophilic heads of surfactants and screen the charge of ionic head groups, which reduce the surface area of the surfactant aggregate (a). And the packing parameter p = V/al[10] may increase to 1/3 < p < 1/2, the value that predicted to form wormlike micelles. The micellar growth is attributed to the reducing of the repulsive force between head groups of surfactant molecules and the interfacial curvature of the aggregates. Such wormlike micellar solutions have high surface activity and high viscoelasticity, which make them useful in oil recovery, drag reducing, home products and personal care products.