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Surfactant specific area

Calculation examples of mixed surfactant adsorption The solid chosen as the model adsorbent was made up of a natural sand (specific area =380 cm2/g) mixed with 5% clay (Charentes kaolinite with specific area = 26.8 m2/g). This material was taken as a model of clayey sandstone reservoirs. [Pg.280]

Figure 15.24 schematically shows a state diagram of the system. Compositions left of the nodal curve will be a B-in-A emulsion, when more A is added, (catastrophic) inversion will take place at the modal line. However, in a specific area where the affinity of the surfactant system towards both phases is approximately equal, transitional inversion may take place. [Pg.335]

In our studies, the nano-sized sihca was synthesized using cheap sodium orthosilicate and sodiirm metasihcate rather than expensive alkoxysilanes. An inverse microemulsion containing NP-5/NP-9 as surfactant and cylcohexane or petroleum ether as the oil was used to carry out the hydrolysis and condensation of sodium orthosilicate or metasilicate using an acidic medium [152, 153]. The spherical silica particles of size 10-20 nm were obtained in a system using cyclohexane as the oil and with sodium orthosihcate of 0.01-0.1 M [152]. The particle size increased as the concentration of sodium orthosihcate and the pH were increased. Sihca particles prepared in basic conditions were more uniform in size than those prepared in an acidic medium. But calcined sihca powders with larger specific areas (350-400 mVg) were obtained for those prepared in an acidic medium. [Pg.288]

A theoretical explanation of experimental results, obtained for modified (non rigid spacer) gemini surfactants, was presented by Andelman and Diamant.47 They noted that the aggregate morphology for dimeric surfactants is related mainly to the influence of the spacer on the specific area X. The geometrical parameter, that determines aggregate shape, is the packing parameter denoted by the formula 48,49... [Pg.179]

In this paper, the capabilities for slick detection at low grazing angles are examined with the use of a standard marine radar system chosen to represent the typical performance of this low cost technology. The resolution and data quality achieved with this kind of instrument are briefly reviewed and compared with those of traditional satellite and airborne radar systems. Two examples of the successful detection in the coastal zone of controlled surfactant slicks with a marine radar system are presented to illustrate the potential for operational and research applications. Finally, the information contained in long-term radar monitoring of a specific area is explored. [Pg.290]

The topics within these chapters are not confined to specific areas. For example, cyclodextrins are discussed not only under supported reagents, but also under separations by inclusion compounds or under chemistry in water. Surfactants have... [Pg.555]

The early work on the interactions of synthetic surfactants and fatty acid anions with proteins was reviewed by Putnam [9] in 1948 and the following 20 years by Steinhardt and Reynolds [10]. The expansion of the field has led more recently to reviews and monograph chapters dealing with specific areas of protein-surfactant interactions, such as the solubilization of membranes by detergents [11] and the use of surfactants in membrane solubilization and reconstitution of membrane proteins [12], as well as more general reviews [13,14,15],... [Pg.238]

If more surfactant is added to water such that its concentration exceeds the critical micelle concentration (CMC), then solute molecules aggregate to form clusters, known as micelles [30], of roughly spherical shape and the interfacial concentration reaches its saturation value, which is equal to Ma, where a is the specific area of a given surfactant adsorbed onto a given substrate. Surfactant molecules aggregate with their hydrophobic tails pointing to the center of the sphere (the core of the micelle) and their hydrophilic part at the micelle surface, in contact with the water phase. [Pg.296]

A most noticeable feature is the maximum in both adsorption isotherms. Since the maximum is present even in the isotherm for the pure surfactant it can be explained only by accepting the idea of declining selectivity with increasing surfactant concentration. Selectivity values for TRS 10-80 surfactant, calculated from Equation (10) with monolayer values determined from cross-sectional areas of surfactant (22A ) and water (8.3A ) molecules, are shown in Figure 10. The specific area for Berea sandstone was assumed to be 1 m /g. [Pg.687]

As a result of regional testing and registration, the use of certain surfactants have been restricted to specific areas of the world, such as the EU, although these products continue to find acceptance and use in other regions. A well-established example is DHTDMAC. [Pg.34]

Surfactants are widely used and find a very large number of applications because of their remarkable ability to influence the properties of surfaces and interfaces, as will be discussed below. Some important applications of surfactants in the petroleum industry are shown in Table 1. Surfactants maybe applied or encountered at aU stages in the petroleum recovery and processing industry, from oilwell drilling, reservoir injection, oilwell production, and surface plant processes, to pipeline and seagoing transportation of petroleum emulsions. This chapter is intended to provide an introduction to the basic principles involved in the occurrence and uses of surfactants in the petroleum industry. Subsequent chapters in this book will go into specific areas in greater detail. [Pg.3]

Here o is the ultimately realized surface charge density in a monolayer of strong fatty acid or a strong fat base. It will be about 1.0 K/m, if the specific area of the monolayer will be equal to 1610 ° m. In this case, 1 m of the air sprayed to form bubbles with radius 1 mm allows us to transfer about 8-10" g of salt impurities. And when the radius of air bubbles wiU be 0.1 mm, then 1 m of air will be able to remove 0.8 g of salt impurities. It will be cations or anions depending on the nature of surfactants adsorbed at the bubble surfaces. Monolayers of ionized fatty acids will entrain the cations, and monolayers of ionized fatty bases will entrain the anions. [Pg.520]

We will consider the initial surfactant solution containing C surfactant molecules per cm. For typical 30 g/1 formulations (3 wt%), C is of the order of 10 molecules/cm. If the surfactant molecules are randomly distributed, the individual molecules are on average about 20 A apart. However, the self-assembly, which occurs for certain surfactants produces a water-oil interface with a specific area, E, in cm /cm of solution, given by the following ... [Pg.160]

The method of deducing solute location from the scattering peak shift in the case of spherical reversed-micelles can be generalized to the case of connected structures (56). For instance, consider the model case of a bicontinous structure, close to the electrical antipercolation threshold. Take the polar volume fraction to be in the range 0.3 to 0.4 and the specific area to be E = 0.02 A /A, which corresponds to a 0.5 M solution of a classical surfactant. In addition, consider a chain length of 15 A and an initial surfactant packing parameter of Po = 1.25. [Pg.183]

We now have two terms, and an additional independent experiment is necessary to obtain the surfactant surface excess concentration. One way to obtain the surfactant surface excess concentration at a water-solid interface is by the depletion method. A known amount of a powder of known specific area solid is immersed in a known volume of an aqueous solution of the surfactant at a known concentration. After several hours of contact (required to reach adsorption equilibrium), the suspension is separated and the surfactant concentration is accurately determined. The difference between initial and final surfactant concentrations multiplied by the volume of liquid gives the amount of surfactant adsorbed on the solid. The surfactant surface excess concentration is obtained by dividing the amount of surfactant adsorbed by the surface of solid (specific area multiplied by weight of solid). The difficulty resides in the exact determination of the final surfactant concentration. In... [Pg.77]

Z]p chain transfer agent concentration inside particle -ab- linkage in condensation aPP atactic polypropylene Os specific area of surfactant comp/y/rj composition distribution / initiation efficiency or functionality fi mole fraction of monomer i / function in comb polymer function in comb polymer... [Pg.780]

At the end of stage I, all surfactant molecules are consumed to cover the total polymer particle area, that is, NavUs[S]w. where [S]w is the surfactant concentration per liter of water and as is the specific area that each surfaaant molecule can cover the particle surface. The time required for stage I can be fotmd by equating Ap to Nav s[S]w- that is, ti = 0.53p" / (fls[S] ) Tbe... [Pg.807]

There are some common patterns related to the adsorption of both polymers and surfactants on solids. In both cases, the adsorption often follows the Langmuir equation and the maximum capacity can be estimated from Langmuir data and/or specific area of solid and of the adsorbed molecule at surface. [Pg.179]

Tajima and co-workers [108] determined the surface excess of sodium dode-cyl sulfate by means of the radioactivity method, using tritiated surfactant of specific activity 9.16 Ci/mol. The area of solution exposed to the detector was 37.50 cm. In a particular experiment, it was found that with 1.0 x 10" Af surfactant the surface count rate was 17.0 x 10 counts per minute. Separate calibration showed that of this count was 14.5 X 10 came from underlying solution, the rest being surface excess. It was also determined that the counting efficiency for surface material was 1.1%. Calculate F for this solution. [Pg.93]

Emulsion Adhesives. The most widely used emulsion-based adhesive is that based upon poly(vinyl acetate)—poly(vinyl alcohol) copolymers formed by free-radical polymerization in an emulsion system. Poly(vinyl alcohol) is typically formed by hydrolysis of the poly(vinyl acetate). The properties of the emulsion are derived from the polymer employed in the polymerization as weU as from the system used to emulsify the polymer in water. The emulsion is stabilized by a combination of a surfactant plus a coUoid protection system. The protective coUoids are similar to those used paint (qv) to stabilize latex. For poly(vinyl acetate), the protective coUoids are isolated from natural gums and ceUulosic resins (carboxymethylceUulose or hydroxyethjdceUulose). The hydroHzed polymer may also be used. The physical properties of the poly(vinyl acetate) polymer can be modified by changing the co-monomer used in the polymerization. Any material which is free-radically active and participates in an emulsion polymerization can be employed. Plasticizers (qv), tackifiers, viscosity modifiers, solvents (added to coalesce the emulsion particles), fillers, humectants, and other materials are often added to the adhesive to meet specifications for the intended appHcation. Because the presence of foam in the bond line could decrease performance of the adhesion joint, agents that control the amount of air entrapped in an adhesive bond must be added. Biocides are also necessary many of the materials that are used to stabilize poly(vinyl acetate) emulsions are natural products. Poly(vinyl acetate) adhesives known as "white glue" or "carpenter s glue" are available under a number of different trade names. AppHcations are found mosdy in the area of adhesion to paper and wood (see Vinyl polymers). [Pg.235]

The introduction of surfactant products into the environment, after use by consumers or as part of waste disposed during manufacture, is regulated by the Clean Water Act, the Clean Air Act, and the Resource Conservation and Recovery Act. In this respect, surfactants are subject to the same regulations as chemicals in general. There are, however, two areas of specific relevance to surfactants and detergent products, ie, biodegradabiUty and eutrophication. [Pg.540]

A summary of a number of correlations proposed for volumetric mass-transfer coefficients and specific interfacial area is presented in Table II, which includes data additional to those of Westerterp et al. (W4). It is apparent that disagreement exists as to the numerical values for the exponents. This is due, in part, to the lack of geometric similarity in the equipment used. In addition, variation in operating factors such as the purity of the system (surfactants), kind of chemical system, temperature, etc., also contribute to the discrepancies. To summarize Table II ... [Pg.306]

Vaterite is thermodynamically most unstable in the three crystal structures. Vaterite, however, is expected to be used in various purposes, because it has some features such as high specific surface area, high solubility, high dispersion, and small specific gravity compared with the other two crystal systems. Spherical vaterite crystals have already been reported in the presence of divalent cations [33], a surfactant [bis(2-ethylhexyl)sodium sulfate (AOT)] [32], poly(styrene-sulfonate) [34], poly(vinylalcohol) [13], and double-hydrophilic block copolymers [31]. The control of the particle size of spherical vaterite should be important for application as pigments, fillers and dentifrice. [Pg.149]


See other pages where Surfactant specific area is mentioned: [Pg.256]    [Pg.138]    [Pg.390]    [Pg.167]    [Pg.62]    [Pg.305]    [Pg.179]    [Pg.210]    [Pg.59]    [Pg.300]    [Pg.463]    [Pg.4]    [Pg.123]    [Pg.798]    [Pg.532]    [Pg.532]    [Pg.152]    [Pg.122]    [Pg.172]    [Pg.968]    [Pg.520]    [Pg.546]    [Pg.140]    [Pg.397]    [Pg.539]    [Pg.595]    [Pg.23]    [Pg.461]   
See also in sourсe #XX -- [ Pg.296 , Pg.300 ]




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