Alkanes surfactants

T. Sottmann and R. Strey Ultralow Interfacial Tension in Water-N-Alkane-Surfactant Systems. J. Chem. Phys. 106, 8606 (1997). 

Different alkanes from pentane to dodecane were incorporated in the micellar solution of CTMABr. In order to investigate the influence of the alkane chain length on the structural and textural properties of the formed mesoporous materials, as mentioned above, all syntheses were performed using a molar ratio of alkane/surfactant equal to 1.0. The crystallization time and temperature are respectively 8 days and 100°C... 

Based on this concept, a crude oil/surfactant/brine system should have phase behavior (e.g., optimum salinity, IFT minima) similar to that of the pure alkane/ surfactant/brine system whose ACN is the same as the crude EACN. However, the concept of EACN is not practically applicable for several reasons. First, all the hydrocarbon compositions of a crade oil are not readily identified. Thus, the EACN of a crude oil cannot be calculated directly using Eq. 7.79. Second, measurement of the EACN of a crude oil requires a series of surfactant solutions to be tested to obtain individual minimum ITT. Then these surfactant solutions are tested against increasing alkane carbon numbers to find minimum IFTs. The ACN at which a surfactant solution also gives the lowest IFT for the crude oil is the EACN of the oil. Finding it is not an easy task. Third, several parameters affect the value of the EACN. Variations in EACN with alcohol cosolvent type, total WOR of the sample, and crude oil composition have been observed (Tham and Lorenz, 1981). In practice, we always select surfactants by scan tests using the actual crude oil for a specific application. 

Sottmann, T. and Strey, R. (1997) Ultralow interfacial tensions in water-n-alkane-surfactant systems. /. Chem. Phys., 106, 8606-8615. 

Viscosity measurements on this O/W microemulsion showed that the extrapolated intrinsic viscosity [rj] was somewhat higher than that expected for hard spheres but was still in agreement with spherical droplets if one assumed some hydration of the ethylene oxide headgroups, an effect that is to be expected because the water-soluble poly (ethylene oxide) is very hydrophilic [50]. For a given alkane/surfactant ratio, almost perfect hard-sphere behavior is obtained under this assumption close to the solubilization boundary... 

A quantitative treatment of surfactant solubility has been successfully made empirically using linear free energy relationships. An important relation is that for the linear free energy of transfer of alkanes to water [23] ... 

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 ... 

Considerable interest arose during the 1970 s and 1980 s in the use of micro-organisms to produce useful fatty adds and related compounds from hydrocarbons derived from the petroleum industry. During this period, a large number of patents were granted in Europe, USA and Japan protecting processes leading to the production of alkanols, alkyl oxides, ketones, alkanoic adds, alkane dioic acids and surfactants from hydrocarbons. Many of these processes involved the use of bacteria and yeasts associated with hydrocarbon catabolism. 

On one hand, /z-alkanes of the molecular range C10-C16 are important starting materials for the synthesis of anionic surfactants. It is possible to dehydrogenate these hydrocarbons to isomeric /z-olefins with internal double bonds olefins) [4], which are also important initial products for the synthesis of an-... 

Table 5 gives typical results of the wax cracking process to surfactant olefins. Compared with the pure a-olefins produced by the oligomerization reactions of ethylene the crack olefins are decreased in quality, especially due to the conjugated diene part (2-4%). Moreover, there are some problems in guaranteeing the wanted amounts of C20-C30 n-alkanes. Therefore in industrially de-... 

Not only the linear Cl0-Cl8 a-olefins but also the linear C10-Cl8 olefins with internal double bonds, the so-called -v /-olefins, are of great importance in surfactant chemistry, n-a-Olefins and n-y-olefins have the same suitability for the manufacture of linear alkylbenzenes, the most important synthetic anionic surfactants, by alkylation of benzene. Nowadays medium molecular weight n- /-olefins are industrially produced by two processes the catalytic dehydrogenation of the corresponding n-alkanes [4,28] and the cometathesis of low and high molecular weight n-v /-olefins, obtained by double-bond isomerization of the isomeric n-a-olefins [29]. 

The effective carbon number neff is helpful in characterizing surfactants with an inner functional group. Surfactants with isomeric structures can be compared by means of the hydrophobicity index / [69], which indicates the influence of the effective length of the alkane chain on cM ... 

FIG. 36 Synergistic mixture of alkane- (paraffin) sulfonates (PS) and fatty alcohol ether sulfates (FAES). Cleaning effect in miniplate test at 50°C, tap water (12° German hardness), 0.075 g of active surfactant mixture per liter. 

The first LCA study of detergent surfactants was sponsored by Procter and Gamble at Franklin Associates Ltd. (FAL) [118]. However, this study does not include alkane- (paraffin) sulfonates since they are absent from the American market. 

The direct reaction of 1-alkenes with strong sulfonating agents leads to surface-active anionic mixtures containing both alkenesulfonates and hydroxyalkane sulfonates as major products, together with small amounts of disulfonate components, unreacted material, and miscellaneous minor products (alkanes, branched or internal alkenes, secondary alcohols, sulfonate esters, and sultones). Collectively this final process mixture is called a-olefinsulfonate (AOS). The relative proportions of these components are known to be an important determinant of the physical and chemical properties of the surfactant [2]. 

The amount of residual sulfonate ester remaining after hydrolysis can be determined by a procedure proposed by Martinsson and Nilsson [129], similar to that used to determine total residual saponifiables in neutral oils. Neutrals, including alkanes, alkenes, secondary alcohols, and sultones, as well as the sulfonate esters in the AOS, are isolated by extraction from an aqueous alcoholic solution with petroleum ether. The sulfonate esters are separated from the sultones by chromatography on a silica gel column. Each eluent fraction is subjected to saponification and measured as active matter by MBAS determination measuring the extinction of the trichloromethane solution at 642 nra. (a) Sultones. Connor et al. [130] first reported, in 1975, a very small amount of skin sensitizer, l-unsaturated-l,3-sultone, and 2-chloroalkane-l,3-sultone in the anionic surfactant produced by the sulfation of ethoxylated fatty alcohol. These compounds can also be found in some AOS products consequently, methods of detection are essential. 

The alkanephosphonic acid dichlorides obtained by these methods are converted with amines, with all reactions carried out in solvents such as acetone, benzene, or diethyl ether at 10°C with triethylamine as HC1 captor. The conversion runs quantitatively followed by a purification with the help of column chromatography with chloroform/methanol in a ratio of 9 1 as mobile phase. The alkanephosphonic acid bisdiethanolamides could be obtained as pure substances with alkane residues of C8, C10, C12, and Ci4. The N-(2-hydroxyethane) alkanephosphonic acid 0,0-diethanolamide esters were also prepared in high purity. The obtained surfactants are generally stable up to 100°C. Only the alkanephosphonic acid bismonomethylamides are decomposed beneath this temperature forming cyclic compounds. 

Firouzi, A Schaefer, DH Tolbert, SH Stucky, GD Chmelka, BE, Magnetic-Field-Induced Orientational Ordering of Alkane Lyotropic Silicate-Surfactant Liquid Crystals, Journal of the American Chemical Society 119, 9466, 1997. 

Many bacteria produce surfactants in response to exposure to hydrocarbons, and these have been demonstrated both for those that degrade alkanes and PAHs (Deziel et al. 1996). The positive effect of adding surfactants is, however, equivocal (Deschenes et al. 1996). 

The surfactants described or characterized for waterflooding are summarized in Table 16-2. Conunercial alkene sulfonates are a mixture of alkene sulfonate, hydroxy alkane sulfonate, and olefin disulfonate [211]. 

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