Surfactant selection

A ring test proved that surfactant-selective electrodes are suitable for quantitative determination of anionic surfactants including alkanesulfonates [21]. The precision of this method, however, does not yet correspond to the state-of-the-art of the two-phase titration. Therefore, further development is needed to enhance the reproducibility and competitiveness of surfactant-sensitive titration. 

TABLE 18.6 Surfactants Characteristics Surfactant Selected Properties ... 

Blends of sodium hypochlorite with 15% HC1 and with 12% HCl/3% HF have been used to stimulate aqueous fluid injection wells(143). Waterflood injection wells have also been stimulated by injecting linear alcohol propoxyethoxysulfate salts in the absence of any acid (144). The oil near the well bore is mobilized thus increasing the relative permeability of the rock to water (145). Temperature effects on interfacial tension and on surfactant solubility can be a critical factor in surfactant selection for this application (146). 

Surfactant concentration surfactant-selective electrode, potentiometry... 

Direct determination of surfactants in complex matrices can also be carried out using ion-selective electrodes. Depending on the membranes and additives used, the detergent electrodes are optimized for the detection of anionic surfactants [81], cationic surfactants [82], and even nonionic surfactants [83]. The devices are sensitive to the respective group of surfactants but normally do not exhibit sufficient stability and reproducibility for their use in household appliances. With further optimization of membrane materials, plasticizers and measurement technology, surfactant-selective electrodes offer high potential for future applications. 

For sensitive quantification in LC-MS analysis of non-ionic surfactants, selection of suitable masses for ion monitoring is important. The nonionic surfactants easily form adducts with alkaline and other impurities present in, e.g. solvents. This may result in highly complicated mass spectra, such as shown in Fig. 4.3.1(A) (obtained with an atmospheric pressure chemical ionisation (APCI) interface) and Fig. 4.3.2 (obtained with an ESI interface). 

The surfactant selected for CPE technique should not have too high a cloud point temperature. In practice, it is possible to obtain almost any desired temperature by choosing an appropriate mixture of surfactants, as cloud point temperatures of mixtures of surfactants are intermediate between those of the two pure surfactants, or by the choice of an appropriate additive (i.e., salts, alcohols, organic compounds) [105]. 

Surfactants enable the polymer particles to disperse effectively without coagulation in the mortar and concrete. Thus, mechanical and chemical stabilities of latexes are improved with an increase in the content of the surfactants selected as stabilizers. An excess of surfactant, however, may have an adverse effect on the strength because of the reduced latex film strength, the delayed cement hydration and excess air entrainment. Consequently, the latexes used as cement modifiers should have an optimum surfactant content (from 5 to 30% of the weight of total solids) to provide adequate strength. Suitable antifoamers are usually added to the latexes to prevent excess air entrainment increased dosages causes a drastic reduction in the air content and a concurrent increase in compressive strength [87, 92-94]. 

Surfactant Selection Based on Drug Solubility in Surfactants. 294... 

Surfactant Selection Based on Drug-Surfactant Compatibility Study. 295... 

Sabatini, D. A., Harwell, J. H. and Knox, R. C. (1999) "Surfactant Selection Criteria for Enhanced Subsurface Remediation." In Innovative Subsurface Remediation Field Testing of Physical, Chemical and Characterization Technologies. M. L. Brusseau, D. A. Sabatini, J. S. Gierke and M. D. Annable, eds. ACS Symposium Series 725, American Chemical Society, Washington, D.C., 8-23. 

The work presented here illustrates that surfactant selection can have a substantial impact on the rates of alcohol partitioning and associated reduction of DNAPL density. More work is needed to develop surfactant/alcohol systems which can minimize interfacial tension reduction while still providing acceptable density conversion rates. Because the potential benefits of in situ density modification are substantial, future work will be directed at system design to minimize interfacial tension reduction. 

In Western Europe, the evolution of surfactant selection is shown from 1976 to 2000 in Figure 1.9. The use of surfactants followed a classical development. Rapid growth in the early period was partly the result of conversion from powder to liquid products in many countries. There was also a notable development in surfactant preferences as formulations became milder. The rise of betaines is an indication of this development, replacing alkanolamides. 

The surfactant selection determines the emulsion properties, such as stability, particle size, viscosity, and internal phase content. A correct balance between the hydrophobic and hydrophilic character of the emulsifier is necessary for minimizing the surfactant concentration at the resin-water interface. The surfactants used in resin emulsification can be ionic (in most cases anionic), nonionic, polymeric, or a combination of these. 

Aqueous Surfactant Selection The selection of aqueous surfactants follows the general rule that the more ionic is the surfactant (i.e.. 

Design of field projects using surfactants selected in Step 7 and a combination of laboratory floods at reservoir conditions, computer simulators, and reservoir history matching. 

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