Carbon surfactants

The activity of three ester spHtting enzymes, Candida antarctica lipase B (CALB), Mucor miehei lipase (MML) and esterase, towards the carbonate surfactant was studied. While CALB and esterase were found to catalyze the hydrolysis of the carbonate bond, MML showed no activity. 

Biodegradation tests have shown that surfactants containing a carbonate bond between the hydrophobic tail and the polar head group are readily biodegradable. In comparative tests such carbonate surfactants biodegrade somewhat faster than the corresponding surfactants containing an ester bond [35]. The carbonate bond is not only susceptible to alkaline hydrolysis... 

Fig. 11 Synthesis route for preparation of carbonate surfactants. DCM stands for dichloromethane...

Discuss the observed differences in permeability between (a) the two alcohols at the same film pressure and (b) the two 18-carbon surfactants at different pressures. In your comments include comparisons of the molecular structure of the surfactants and the efficiencies of these monolayers in retarding evaporation. 

The acid deactivation mechanism in hydrocarbon media is supplementary to the neutralizing action of carbonate-surfactant hard-core RMs. Traces of strong sulfur, nitrogen or halogen acids are scavenged by neutral detergents, with the... 

The best-known sweetness inhibitor is sodium dodecyl sulfate (SDS), also known as sodium lauryl sulfate. This substance is a twelve carbon surfactant that is quite commonly used as a detergent in toothpaste. The observation is often made that after brushing one s teeth, the taste of orange juice is unusually bitter. This has been ascribed to the presence of SDS in the dentifrice (6 ). 

Crude oil and water mixtures also formed stable emulsions when treated with the switchable amidine carbonate surfactant, and the emulsion could be broken by exposure to argon to give two separate layers. This shows the great potential... 

Glycerin, glycol ethers, hydroxyethyl cellulose, isopropylamines. propylene carbonate, surfactants-... 

Banhegyi, G., Marosi, G. et al. (1992) Studies of thermally stimulated current in polypropylene/calcium carbonate/surfactant systems. Colloid Polymer Sci., 270, 113-127. 

The fluorine NMR chemical shifts of terminally fluorinated cationic surfactants 12,12,12-trifluorododecyltrimethylammonium bromide and 10,10,10-tri-fluorodecyltrimetylammonium bromide are similar to those of the corresponding anionic and nonionic surfactants with a terminal trifluoromethyl group [32]. When the counterion is fluoride, instead of bromide, the chemical shift of the fluoride counterion is concentration dependent. The trifluoromethyl chemical shifts were interpreted utilizing a double-equilibrium model. The aggregation number was estimated to be 25 in dilute solutions from the curvature of the chemical shift concentration plots near the first cmc. Above the second cmc, the aggregation number was assumed to be 60, considered the spatial limit for 12-carbon surfactant chains in a spherical micelle. 

Table XI-1 (from Ref. 166) lists the potential-determining ion and its concentration giving zero charge on the mineral. There is a large family of minerals for which hydrogen (or hydroxide) ion is potential determining—oxides, silicates, phosphates, carbonates, and so on. For these, adsorption of surfactant ions is highly pH-dependent. An example is shown in Fig. XI-14. This type of behavior has important applications in flotation and is discussed further in Section XIII-4.

A selection of important anionic surfactants is displayed in table C2.3.1. Carboxylic acid salts or tire soaps are tire best known anionic surfactants. These materials were originally derived from animal fats by saponification. The ionized carboxyl group provides tire anionic charge. Examples witlr hydrocarbon chains of fewer tlran ten carbon atoms are too soluble and tliose witlr chains longer tlran 20 carbon atoms are too insoluble to be useful in aqueous applications. They may be prepared witlr cations otlrer tlran sodium. 

Extensive discussions have focused on the conformation of the alkyl chains in the interior ". It has been has demonstrated that the alkyl chains of micellised surfactant are not fully extended. Starting from the headgroup, the first two or three carbon-carbon bonds are usually trans, whereas gauche conformations are likely to be encountered near the centre of tlie chain ". As a result, the methyl termini of the surfactant molecules can be located near the surface of the micelle, and have even been suggested to be able to protrude into the aqueous phase "". They are definitely not all gathered in the centre of tire micelle as is often suggested in pictorial representations. NMR studies have indicated that the hydrocarbon chains in a micelle are highly mobile, comparable to the mobility of a liquid alkane ... 

MIBK is a flammable, water-white Hquid that boils at 116°C. It is sparingly soluble in water, but is miscible with common organic solvents. It forms an a2eotrope with water as shown in Table 2. Condensation of MIBK with another methyl ketone can produce ketones containing 9—15 carbons. For example, condensation with acetone produces diisobutyl ketone, and self-condensation of two MIBK molecules produces 2,6,8-trimethyl-4-nonanone [123-17-1]. Condensation with 2-ethylhexanal gives 1-tetradecanol (7-ethyl-2-methyl-4-undecanol), avaluable surfactant intermediate (58). 

Wettabihty is defined as the tendency of one fluid to spread on or adhere to a soHd surface (rock) in the presence of other immiscible fluids (5). As many as 50% of all sandstone reservoirs and 80% of all carbonate reservoirs are oil-wet (10). Strongly water-wet reservoirs are quite rare (11). Rock wettabihty can affect fluid injection rates, flow patterns of fluids within the reservoir, and oil displacement efficiency (11). Rock wettabihty can strongly affect its relative permeabihty to water and oil (5,12). When rock is water-wet, water occupies most of the small flow channels and is in contact with most of the rock surfaces as a film. Cmde oil does the same in oil-wet rock. Alteration of rock wettabihty by adsorption of polar materials, such as surfactants and corrosion inhibitors, or by the deposition of polar cmde oil components (13), can strongly alter the behavior of the rock (12). 

Sacrificial adsorption agents such as lignosulfonates (148—151) can be used to reduce the adsorption of more expensive polymers and surfactants. Other chemicals tested include poly(vinyl alcohol) (152), sulfonated poly(vinyl alcohol) (153), sulfonatedpoly(vinylpyrrohdinone) (153), low molecular weight polyacrylates (154), and sodium carbonate (155). 

Lignosulfonate has been reported to increase foam stabihty and function as a sacrificial adsorption agent (175). Addition of sodium carbonate or sodium bicarbonate to the surfactant solution reduces surfactant adsorption by increasing the aqueous-phase pH (176). 

Alkyl or aryl phosphonates, which contain a carbon—phosphoms bond, are comparatively more stable. They are of interest as antiscaling additives and corrosion inhibitors for cooling towers and heat exchangers (see Dispersants Water, industrial water treatment), surfactants (qv), sequestrants, and textile-treating agents. Trialkyl phosphites are usehil as esterification (qv) reagents. 

The production of alkylphenols exceeds 450,000 t/yr on a worldwide basis. Alkylphenols of greatest commercial importance have alkyl groups ranging in size from one to twelve carbons. The direct use of alkylphenols is limited to a few minor appUcations such as epoxy-curing catalysts and biocides. The vast majority of alkylphenols are used to synthesize derivatives which have appUcations ranging from surfactants to pharmaceuticals. The four principal markets are nonionic surfactants, phenoUc resins, polymer additives, and agrochemicals. 

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