Surfactant from crude oils

Coadsorption of surfactant and oil on the solid may enhance surfactant adsorption by reducing electrostatic repulsion between surfactant head-groups in the adsorbed layer (23, 24) or may decrease surfactant adsorption by reducing the packing density of surfactant molecules in the adsorbed layer or by occupation of some of the adsorption sites on the solid surface by oil (23, 25). Furthermore, natural surfactants from crude oil may occupy some of the adsorption sites and thus act as sacrificial adsor-... 

With chemical treatment, the natural surfactants in crude oil can be activated [1384]. This method has been shown to be effective for highly viscous crude oil from the Orinoco Belt that has been traditionally transported either by heating or diluting. The precursors to the surfactants are preferably the carboxylic acids that occur in the crude oil. The activation occurs by adding an aqueous buffer solution [1382,1383]. The buffer additive is either sodium hydroxide in combination with sodium bicarbonate or sodium silicate. Water-soluble amines also have been found to be suitable [1506]. 

Surfactants can be produced from both petrochemical resources and/or renewable, mostly oleochemical, feedstocks. Crude oil and natural gas make up the first class while palm oil (+kernel oil), tallow and coconut oil are the most relevant representatives of the group of renewable resources. Though the worldwide supplies of crude oil and natural gas are limited—estimated in 1996 at 131 X 1091 and 77 X 109 m3, respectively [28]—it is not expected that this will cause concern in the coming decades or even until the next century. In this respect it should be stressed that surfactant products only represent 1.5% of all petrochemical uses. Regarding the petrochemically derived raw materials, the main starting products comprise ethylene, n-paraffins and benzene obtained from crude oil by industrial processes such as distillation, cracking and adsorption/desorption. The primary products are subsequently converted to a series of intermediates like a-olefins, oxo-alcohols, primary alcohols, ethylene oxide and alkyl benzenes, which are then further modified to yield the desired surfactants. 

Fordedal and Sjoblom used dielectric spectroscopy to study several real erode oil emulsions and model systems stabilized with either separated asphaltenes and resins from crude oil or by commercial surfactants (55). Emulsions could be stabilized by the asphaltene fraction alone, but not by the resin fraction alone. A study of a combination of mixtures shows an important interaction between emulsifying components. F0rdedal et al. used dielectric spectroscopy to study model emulsions stabilized by asphaltenes extracted from crude oils (56). Analysis showed that the choice of organic solvent and the amount of asphaltenes, as well as the interaction between these variables, were the most significant parameters for determining the stability of the emulsions. 

FIGURE 1.5 Intermediates and feedstocks for the production of anionic and nonionic surfactants derived from crude oil and natural gas. 

By contrast, the specific components of crude oil that have been most closely associated with foam behavior reveal radically different chemistry to these simple hydrocarbon chain surfactants. As exemplified by the work of Poindexter et al. [4, 20], those components can be listed as asphaltenes, resins, and waxes. Of these, arguably asphaltenes are the most important. These components are derivatives of polycyclic aromatics, which are distinguished from other crude oil components by insolubility in short-chain n-alkanes such as n-heptane. They are, however, soluble in toluene. Resins are soluble in short-chain alkanes and are therefore usually extracted from crude oil by adsorption onto silica from solution. Both asphaltenes and resins can even each be present in crude oil at concentrations in excess of 15 wt.%. Such extremely high concentrations usually lead to crude oils of high density and high viscosity—so-called heavy crudes (see, e.g., reference [4]). 

The isolation of natural surfactants, using various methods such as separation by emulsification (Acevedo et al, 1992), chromatographic methods (Ramljak et al, 1977, Acevedo et al, 1999 Borges, 2009) has been reported. In this research, a modified chromatographic procedure, based on the proposed by Ramljak in 1977, has been used to isolate natural surfactants in crude oil and thus adapt to the properties of Venezuelan extraheavy crude oil from the Orinoco oil belt, followed by structural characterization of these surfactants, especially those derived from the acid. As mentioned above these natural surfactants play an important role in the stabihty of emulsions, there is great interest in... 

One of the most interesting opportunity fuels related to petroleum coke is Orimulsion , a highly volatile product produced from Venezuelan crude oil. Orimulsion is a fuel used as a substitute for heavy oil in large utility and industrial boilers. It is conq>rised of 70 percent bitumen from the Orinoco belt in Venezuela, and 30 percent water. A surfactant, or stabilizing agent, is used as well. Mti ly the product Orimulsion 100 was marketed this product has been enhanced and a new formulation, Orimulsion 400 is being produced. The new formulation involves a different surfactant and the exclusion of magnesium nitrate from the product [56-58]. Orimulsion, like petroleum coke and the heavy oils and pitches previously discussed, is derived from crude oil and related products. 

Tests were performed at 75°C using a University of Texas Model 500 spinning drop tensiometer. Active surfactant concentration in the aqueous phase prior to oil addition was 0.50% wt. The Kem River crude oil was from the Patricia Lease. The pH of the deionized water surfactant solutions was 8. The pH of the aqueous NaCl surfactant solutions was 9.5 unless otherwise noted. values represent the average deviation of two or three measurements at different times (0.75-1 h apart). D.I., deionized. 

Water-in-oil macroemulsions have been proposed as a method for producing viscous drive fluids that can maintain effective mobility control while displacing moderately viscous oils. For example, the use of water-in-oil and oil-in-water macroemulsions have been evaluated as drive fluids to improve oil recovery of viscous oils. Such emulsions have been created by addition of sodium hydroxide to acidic crude oils from Canada and Venezuela. In this study, the emulsions were stabilized by soap films created by saponification of acidic hydrocarbon components in the crude oil by sodium hydroxide. These soap films reduced the oil/water interfacial tension, acting as surfactants to stabilize the water-in-oil emulsion. It is well known, therefore, that the stability of such emulsions substantially depends on the use of sodium hydroxide (i.e., caustic) for producing a soap film to reduce the oil/water interfacial tension. 

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... 

Self-generated surfactants (produced from fossil fuels by a chem-ical/physical process) or natural surfactants (exiting in fossil fuels) are derived from the inherent organic acids and replaceable acidic protons which are present in crude oils or bitumens (e.g., mercaptans). Yen and Farmanian (2) isolated native petroleum fractions that form surfactants and contain hydrogen dispiacable components including one, two, three, or four of die following types ... 

The point at which, supposedly, 50% of the acid species is transformed in salt corresponds to the half-neutrahzation, i.e., when half the alkahne required to reach the equivalence point has been added. This position corresponds to a buffer zone in which the variation of pH is small with respect to the amoimt of added neutralization solution (Fig. 14 left plot). Hence, in this region a very slight variation of pH can produce a very large variation of neutralization (Fig. 14 right plot), i.e., a considerable alteration of the relative proportion of AH and A . Far away from this pH, the opposite occurs. Consequently, the pH could be used to carry out a formulation scan, but the scale is far from hnear and the variation of pH does not render the variation of the characteristic parameter of the actual surfactant mixture that is at interface [77,78]. The appropriate understanding of the behavior of this kind of acid-salt mixture is particularly important in enhanced oil recovery by alkaline flooding [79,80] and emulsification processes that make use of the acids contained in the crude oils [81-83]. 

In aqueous surfactant solutions, either by circumstance or design, non—surface active organic species may be present. Examples are oil recovery, where crude oil is present, or micellar—enhanced ultrafiltration, where micelles are being used to effect a separation of dissolved organic pollutants from water. The ability of mixed micelles to solubilize organic solutes has received relatively little study. In addition, the solubilization of these compounds by micelles may change the monomer—micelle equilibrium compositions. 

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