Surfactants design

SuperAII 38 is a blend of ionic surfactants designed to break down hydrocarbon contaminants into microscopic particles. According to the vendor, it can be used for spiU control. 

The development of improved methods of surfactant design required progress in several other areas (1) understanding the mechanisms of dispersion flow in porous media, to determine which physical properties should be measured, and how their values would affect sweep control (2) measurements of these properties that are valid at the conditions under which the surfactants will be used and (3) understanding of how the values of these parameters depend on phase behavior, molecular structure, and other thermodynamic variables. 

The quantitative description of these mechanisms is required for the construction of meaningful flow simulators that can be scaled up from the dimensions of laboratory experiments to the dimensions of field use, and for scientifically based surfactant design. 

Interfacial Properties, Dispersion and Phase Behavior, and Surfactant Design... 

Determination of Important Parameters in Surfactant Design. Recent work (Chapters 8 and 9) demonstrates the utility of correlating test results with surfactant structures. But as the complexities of pore level mechanisms, dispersion properties, and fluid behavior become better understood, it is also becoming increasingly clear that a variety of physical property measurements will be required for advanced surfactant design. Many of these measurements will be needed at pressures (ca. 10 MPa) that are characteristic of gas-flood conditions. 

In summary, reservoir characteristics establish most of the parameters that control capillary snap-off, and interfacial tensions are the only controllable snap-off parameters. The dependencies of interfacial tensions on phase behavior and surfactant structure define many of the objectives of the surfactant designer. 

Phase Behavior and Surfactant Design. As described above, dispersion-based mobility control requires capillary snap-off to form the "correct" type of dispersion dispersion type depends on which fluid wets the porous medium and surfactant adsorption can change wettability. This section outlines some of the reasons why this chain of dependencies leads, in turn, to the need for detailed phase studies. The importance of phase diagrams for the development of surfactant-based mobility control is suggested by the complex phase behavior of systems that have been studied for high-capillary number EOR (78-82), and this importance is confirmed by high-pressure studies reported elsewhere in this book (Chapters 4 and 5). 

Figure 10. Illustration of why surfactant design requires the study of both conjugate phases.

The development of a rational strategy of surfactant design requires some way of estimating the dependence of phase parameters on surfactant structure and reservoir characteristics (e.g., salinity). Chapter 9, by Borchardt, describes a method for correlating phase and physical properties of mobility control surfactants with their molecular structures. 

Surfactant Designation Moles EO/ Mole ROH EO % wt. SuDolier T r°c Surfactant Concentration (% wt.) Initial Foam Volume (cc)... 

It should be noted that the field tests were made with only one type of surfactant, and without benefit of many recent research advances in such areas as high-pressure phase behavior and surfactant design, mechanisms of dispersion formation and disappearance, and mechanisms of dispersion flow through porous media. Furthermore, the design and successful performance of field tests pose many technological challenges in addition to those encountered in the prerequisite experimental and theoretical research. 

CNC SPANSCOUR EPS is an anionic surfactant designed as the complete detergent for the scouring of Spandex containing materials. 

This material is an anionic surfactant designed to improve greatly the dyeing of Nylon with the use of neutral metallic dyestuffs and acid dyestuffs. This material is normally used in the presence of a small amount of sodium acetate and will be very beneficial in obtaining smooth even dyeings of Nylon. 

The surface activity of silicones is often exploited by using them as additives. For this reason, aspects of the two most important additive forms, copolymers and surfactants, are also included in this discussion. These two classes come together in the relatively low molecular weight PDMS-poly(alkylene oxide) block and graft copolymers that are commonly used as polyurethane foam stabilizers. Other short-chain silicone surfactants designed for aqueous systems and other silicone-organic copolymers are also available. 

There are several theories to guide new surfactant design and explain surfactant phase behavior. These theories are solubilization ratio (SR), R-ratio, and... 

Joseph M. DeSimone (BCST Liaison) is William R. Kenan, Jr., Distinguished Professor of Chemistry and Chemical Engineering at North Carolina State University and the University of North Carolina. He is also director of the National Science Foundation Science and Technology Center for Environmentally Responsible Solvents and Processes. He received his B.S. in chemistry form Ursinus College and his Ph.D. in chemistry from Virginia Polytechnic Institute and State University. His areas of interest include polymer synthesis in supercritical fluids, surfactant design for applications in interfacial chemistry, and polymer synthesis and processing—from fundamental aspects of chemical systems to the most efficient and environmentally friendly ways to manufacture polymers and polymer products. 

Many volatile low-molecular-weight organics are completely miscible with carbon dioxide at relatively modest temperatures and pressures. However, nonvolatile compounds or those with higher molecular weights, especially polymers, are often insoluble. Insoluble liquid compounds may be dispersed into CO2 with the aid of appropriate surfactants to form a kinetically stable o/c emulsion [10,11]. Stable emulsions are important in separation processes, heterogeneous reactions and materials formation processes, such as precipitation with a compressed fluid antisolvent [40]. These emulsions are the precursors to solid latex particles in dispersion polymerization. Stabilization of o/c emulsions has been studied in-situ to understand surfactant design for polymerization [10,11]. 

D. J. MiUiron, A. P. AlMsatos, C. Pitois, C. Edder, J. M. J. Frechet, Electroactive Surfactant Designed to Mediate Electron Transfer Between CdSe Nanocrystals and Organic Semiconductors. Adv. Mater. 2003,15,58-61. 

Restricting our continuous phase to carbon dioxide means that the monomers in question must be relatively C02-phobic (in other words hydrophilic or at least very polar). Note that this greatly reduces the number of monomers that would be viable candidates for inverse emulsion polymerization in CO2 (or in another supercritical continuous phase) indeed even some water-soluble monomers such as acrylic acid are miscible with CO2 under relatively mild conditions. We will examine the issues surrounding monomer selection and surfactant design as they relate to the phase behavior of the system in the next section. 

Inexpensive, efTective surfactant design is probably the key issue that must be dealt with in order to render emulsion polymerization in carbon dioxide a viable process, and hence advances in the understanding of the solvent behavior of CO2 must continue to drive this application forward. 

Considering all of the possible chemical structures available to the synthetic chemist for surfactant design, it is necessary to have some system of classification to guide the user to the material best suited to immediate and future needs. It therefore seems reasonable to have clearly in mind where one wants to go before looking for the best route to get there. 

The difficulties in assessing the absolute counting efficiency of heterogeneous samples are outweighed by the convenience of this method of counting unknowns and by the availability of a myriad of commercial mixtures of nonionic and anionic surfactants "designed" for LSC. We have therefore retreated to an attempt to emphasize some of the less obvious pit-falls in such systems. 

Figure 13.4 Essentiai aspects of surfactant design for polystyrene-montmorillonite nanocomposites. Reproduced from Ref [78] with permission.

ShelP published information on the biodegradability of methyl-substituted surfactants. The Shell and P G research paved the way for new anionic surfactant design with controlled alkyl substitution on the hydrophobe and acceptable biodegradability. Selective isomerization of the linear olefins using recent advances in zeolite catalytic sieve technology are the key technology advancements for these new surfactant hydrophobes, which require only one additional step in the current Shell linear alcohol process as shown in Figure 6.14. 

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