Inexpensive Surfactants

A significant limitation of using SCCO2 in materials applications is that it is a feeble solvent for most polymers [23]. Certain amorphous fiuoropolymers are exceptions to this rule [14], and these materials have been used, for example, as 

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By 1980, research and development shifted from relatively inexpensive surfactants such as petroleum sulfonates to more cosdy but more effective surfactants tailored to reservoir and cmde oil properties. Critical surfactant issues are performance in saline injection waters, adsorption on reservoir rock, partitioning into reservoir cmde oil, chemical stabiUty in the reservoir, interactions with the mobiUty control polymer, and production problems caused by resultant emulsions. Reservoir heterogeneity can also greatly reduce process effectiveness. The decline in oil prices in the early 1980s halted much of the work because of the relatively high cost of micellar processes. 

Surfactants have been widely used to reduce the interfacial tension between oil and soil, thus enhancing the efficiency of rinsing oil from soil. Numerous environmentally safe and relatively inexpensive surfactants are commercially available. Table 18.6 lists some surfactants and their chemical properties.74 The data in Table 18.6 are based on laboratory experimentation therefore, before selection, further field testing on their performance is recommended. The Texas Research Institute75 demonstrated that a mixture of anionic and nonionic surfactants resulted in contaminant recovery of up to 40%. A laboratory study showed that crude oil recovery was increased from less than 1% to 86%, and PCB recovery was increased from less than 1% to 68% when soil columns were flushed with an aqueous surfactant solution.74-76... 

Aqueous fracture foams are the least expensive not only because of the low cost of water but also due to the availability of inexpensive surfactants that foam water and brines easily and effectively. Oil and alcohol foams are much more costly due to the... 

With such a variety of available structures, how does one choose the proper surfactant for a particular purpose Alternatively, why are only certain surfactants used for a particular purpose and not other surfactants Economic factors are often of major importance—unless the cost of using the surfactant is trivial compared to other costs, one usually chooses the most inexpensive surfactant that will do the job. In addition, such considerations as environmental effects (biodegradability, toxicity to and bioconcentration in aquatic organisms) and, for personal care products, skin irritation are important considerations. The selection of the best surfactants or... 

The anionic surface-active compounds with the largest volume of production are the alkylbenzene sulfonates. Here, the possibility of an easy insertion of a sulfonic acid group into the benzene molecule is used to obtain inexpensive surfactants. Suitable starting materials are alkylbenzenes with an alkyl chain length of ca. 12 carbon atoms, obtained by the application of olefines or monochloroalkanes to the benzene ring. 

The linear sulfonates are inexpensive surfactants with optimal properties for many applications. By mixing with other kinds of surface-active agents synergistic effects can occur that allow adjustment of the properties of the mixtures to special demands. 

The main current U.S. producers of petroleum sulfonates are Penreco, EXXON, Shell (natural), Pilot Chemical (synthetic), and Witco [4,64,69,77], Note that like lignosulfonates, petroleum sulfonates are particularly inexpensive surfactants with good performances. Their production amounts to -10% of that of the total sulfonates. Since in EOR applications they enable ultra-low inlerfa-cial tensions (down to 0.1 pN/m) to be obtained [1,4,64,69,76], their manufacture is likely to be boosted by the strong current increase in crude oil market prices. 

Beckman and coworkers [11, 58] reported that inexpensive poly(ether carbonate) (PEC) copolymers have been reported to be soluble in CO2 under moderate conditions and could function as building blocks for inexpensive surfactants, but numerous practical difficulties remain. These hydrocarbon systems involve PECs synthesized by aluminium-catalyzed copolymerization of cyclic ethers with CO2 (i.e.. Ml = ethylene oxide, propylene oxide, cyclohexene oxide M2 = CO2). These copolymers were found to be soluble in liquid CO2 at concentrations of 0.2-1.5% (w/v) at ambient temperatures and pressures in the range 120-160 bar - that is, significantly above the liquid-vapour pressure for CO2. These statistical copolymers were generated from very inexpensive feed-stocks and are thus appealing as building blocks for cheap surfactants. The enhanced solubility of these copolymers with respect to poly(propylene oxide) is speculated to arise, at least in part, from specific... 

One of the often noted properties of SMEs is their lime soap dispersing properties. Lime soap, or the calcium salts of long-chain fatty acids, collects in showers and tubs as soap scum. In laundry, lime soap built up on fabric over time can cause graying. YeL soap is an inexpensive surfactant and its incorporation into formulations can be very beneficial. Using both a lime soap dispersing surfactant and soap can overcome the disadvantages of using soap alone. 

In 1950 the Fischer-Tropsch synthesis was banned in Germany by the allied forces. Sinarol, a high paraffinic kerosene fraction sold by Shell, was used as a substitute. This ban coincided with the rapid development of the European petrochemical industry, and in due time Fischer-Tropsch synthesis applied to the production of paraffins became uneconomic anyway. After the war there was a steady worldwide increase in the demand for surfactants. In order to continually meet the demand for synthetic detergents, the industry was compelled to find a substitute for /z-paraffin. This was achieved by the oligomerization of the propene part of raffinate gases with phosphoric acid catalyst at 200°C and about 20 bars pressure to produce tetrapropene. Tetrapropene was inexpensive, comprising a defined C cut and an olefinic double bond. Instead of the Lewis acid, aluminum chloride, hydrofluoric acid could now be used as a considerably milder, more economical, and easier-to-handle alkylation catalyst [4],... 

Surfactants and Colloids in Supercritical Fluids Because very few nonvolatile molecules are soluble in CO2, many types of hydrophilic or lipophilic species may be dispersed in the form of polymer latexes (e.g., polystyrene), microemulsions, macroemulsions, and inorganic suspensions of metals and metal oxides (Shah et al., op. cit.). The environmentally benign, nontoxic, and nonflammable fluids water and CO2 are the two most abundant and inexpensive solvents on earth. Fluorocarbon and hydrocarbon-based surfactants have been used to form reverse micelles, water-in-C02... 

CE has been used for the analysis of anionic surfactants [946,947] and can be considered as complementary to HPLC for the analysis of cationic surfactants with advantages of minimal solvent consumption, higher efficiency, easy cleaning and inexpensive replacement of columns and the ability of fast method development by changing the electrolyte composition. Also the separation of polystyrene sulfonates with polymeric additives by CE has been reported [948]. Moreover, CE has also been used for the analysis of polymeric water treatment additives, such as acrylic acid copolymer flocculants, phosphonates, low-MW acids and inorganic anions. The technique provides for analyst time-savings and has lower detection limits and improved quantification for determination of anionic polymers, compared to HPLC. 

Mention should also be made in this section of niosomes, which are nonionic surfactant vesicles that have shown promise as inexpensive and chemically stable alternatives to liposomes [67]. 

Surfactants disrupt the cell wall by solubilizing the lipids in the wall. Sodium dodecylsulfate (SDS), sodium sulfonate, Triton X-100, and sodium taurocholate are examples of the surfactants often employed in the laboratory. Alkali treatment disrupts the cell walls in a number of ways including the saponification of lipids. Alkali treatment is inexpensive and effective, but it is so harsh that it may denature the protein products. Organic solvents such as toluene can also rupture the cell wall by penetrating the cell wall lipids, swelling the wall. When red blood cells or a number of other animal cells are dumped into pure water, the cells can swell and burst due to the osmotic flow of water into the cells. 

As an inexpensive source of acid, a large amount of the sulfuric acid that is produced is used for the manufacture of other mineral acids. It is also used to produce sulfates, such as ammonium sulfate (a low-grade fertilizer), sodium sulfate (used in the production of paper), and aluminum sulfate (used in water treatment), as well as organic sulfates (used as surfactants). Sulfuric acid is also a good catalyst for many reactions, including the transformation of ethanol into ethylene or ethyl ether. 

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