Surfactant-alcohol

Microbial-enhanced oil recovery involves injection of carefully chosen microbes. Subsequent injection of a nutrient is sometimes employed to promote bacterial growth. Molasses is the nutrient of choice owing to its low (ca 100/t) cost. The main nutrient source for the microbes is often the cmde oil in the reservoir. A rapidly growing microbe population can reduce the permeabiHty of thief zones improving volumetric sweep efficiency. Microbes, particularly species of Clostridium and Bacillus, have also been used to produce surfactants, alcohols, solvents, and gases in situ (270). These chemicals improve waterflood oil displacement efficiency (see also Bioremediation (Supplement)). 

The industrially used homogeneous catalysts for the hydroformylation of higher molecular olefins into aldehydes, which are hydrogenated to the corresponding surfactant alcohols, are cobalt carbonyl [47] or cobalt carbonylItert-phosphine complexes [48]. 

Surfactant alcohols are linear, primary alcohols with carbon chain lengths in the C12-C14 and the C16-C18 range. Surfactant alcohols can be derived from either petrochemical or oleochemical feedstocks, and thus are referred to either as synthetic alcohols or as natural (oleochemical) alcohols. Petrochemical feedstocks used for surfactant alcohol production are ethylene and, to a lesser degree, paraffins. 

Polyethylene and polystyrene are examples of plastics subject to environmental stress cracking. Crack resistance tests have shown that surfactants, alcohols, organic acids, vegetable and mineral oils, and ethers provide an active environment for stress cracking of polyethylene. Table 6 lists typical sterile devices and plastic materials used to fabricate them, while Tables 7-9 list the potential effects of sterilization processes on polymeric materials. The effect of gamma irradiation on elastomeric closures has been studied by the Parenteral Drug Association [15]. 

It may be expected that the rates of transfer of surfactant and alcohol, Dx and Dy, are affected by the negative feedback of Z. In other words, the diffusion rate, Dx, of surfactant from the aqueous phase to the interface may decrease with the net increase in the concentration of surfactant at the interface, X plus Z . A similar situation may hold for the diffusion rate, Dy, of alcohol from the aqueous phase to the interface. Hence, the system kinetics may be considered under the following assumptions (a) the concentration of surfactant and alcohol in the bulk aqueous phase, Xb and Yb, remain constant (b) the rates of diffusion of surfactant alcohol from the bulk aqueous phase to the interface are expressed as Dx(Xb - X ) and Dy(Yb - Yj), respectively (c) the negative feedback of Zi on the diffusion of X and Y are given Yb - kiZj and - k2Zj, respectively (d) the rate of step (iv) is expressed as a function, F(Xi( Yj), with the rate constant k3 and (e) the rate of step (iv) is expressed as a function, G(Zj), with the rate constant k4. 

S.S. Talmage, Environmental and Human Safety of Major Surfactants Alcohol Ethoxylates and Alkylphenol Ethoxylates, Soap and Detergent Association, Lewis, Boca Raton, FL, 1994. 

Talmage S (1994) Environmental and human safety of major surfactants alcohol ethoxy-lates and alkylphenol ethoxylates. Lewis Publishers, Ann Arbor, MI... 

Alkyl ether sulfates with chain lengths ranging from to Cw are quantitatively the most important products currently based on fatty alcohols. It is estimated, that about 20 % of all surfactant alcohols -about 40 % of all fatty alcohols in the coconut range (C,2 Ci,) - are used in the form of alkyl ether suirateg ( ). Alkyl ether sulfates are the most important group of anionic surfactants after linear alkyl-benzenesulfonate (LAS) (2). 

In conclusion, the synthesis of mesostructured aluminophosphate / surfactant materials in alcoholic systems yields a mixture of an inverse hexagonal and a lamellar phase, the latter of which is more stable, as its formation is relatively favoured by higher temperatures and/or longer reaction times. The synthesis is highly cooperative the surfactant / alcohol systems without the inorganic species do not show any lyotropic behaviour. 

In Situ Density Modification of Entrapped Dense Nonaqueous-Phase Liquids (DNAPLs) using Surfactant/Alcohol Solutions... 

Figure I Density modified displacement of chlorobenzene with 4 % Aerosol MA/OT + 25 % n-butanol (A) corresponds to initial injection of chlorobenzene, (B) and (C) correspond to increasing pore volumes of surfactant/alcohol flood ( (C) is a close-up of the outlet of the cell). Dyed chlorobenzene is outlined in figures above. Note that lines are also visible in B indicating the movement of dyed surfactant/alcohol solution.

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 the preceding equation, the first term on the left-hand side is the reference state chemical potential per surfactant molecule of an infinite-size aggregate and the second term involving yF accounts for the interfacial tension to which this infinite aggregate is subjected. Theterms on theright-hand side represent the chemical potentials of the surfactant, alcohol, and oil in the bulk phase in equilibrium with the molecules at the interface. Using eq 3.1, the above equation can be rewritten as... 

Headgroup Steric Interactions. This contribution is expressed as that for mixed surfactants. Because, in the present case, the free energy is expressed per surfactant molecule (not surfactant + alcohol molecule), one can write... 

A.l. A Water-in-Oil Droplet Microemulsion. (a) Description of the Phase. The microemulsion system is composed of Ngo droplets of various sizes g (each consisting of surfactant, alcohol, oil and water molecules) and outside the droplets,Noo oil molecules, Also surfactant molecules, Nao alcohol molecules, and ATW0 water molecules. The subscript g for a droplet denotes the total number of molecules of different kinds present in it (i.e., g =gs +8a +go +gw). The A ao alcohol molecules outside the droplets are present both as singly dispersed molecules and as aggregates. The number of alcohol aggregates containing j alcohol molecules is denoted by Njao-... 

Levent Yuksel, Group VP-Care Surfactants Alcohols... 

A qualitative evidence of the above are the data reported in [52]. It has been established that there is a correlation between the calculated rate of internal diffusion foam collapse and the experimentally determined rate. To obtain a stable foam from poor surfactants (alcohols, acids, etc.) under these conditions is hardly possible because of either insufficient dynamic elasticity of foam films or the lack of equilibrium elasticity (for films from insoluble surfactants). Furthermore, the n barrier for films from acid or alcohol solutions is low and the typical capillary pressures for a real foam are sufficient to induce disturbance of the film equilibrium and, respectively, foam collapse. 

The results showed distinct and regular changes for the aqueous solubility region in pentanol surfactant mixtures. With increased electrolyte content, the "minimum amount of water for solubility was enhanced, the solubility limit towards the pentanol water axis was shifted to higher soap concentrations, and the "maximum solubility of the aqueous sodium chloride solution was obtained for higher surfactant alcohol ratios (Figure 2). 

The shift of the solubility limit against the pentanol water axis (Figure 2, left) towards higher concentration of soap with an added electrolyte is mainly related to the solubility of the water in pentanol. The solubility of the aqueous solution in pentanol is reduced with increasing sodium chloride concentration this fact accounts for the lowering of solubility at low surfactant alcohol ratios. 

The results showing augmentation of the surfactant alcohol ratio for maximum aqueous solubility with added electrolytes are not amenable to a similarly simple explanation, and the influence of the presence of electrolytes must be discussed against the relative stability of the inverse micelles and of the lyotropic liquid crystalline phase with which the inverse micellar solution is in equilibrium (7). 

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