Alkane carbon number

From the retention of the alkanes in n-octane extrapolated to an alkane carbon number of 3... 

The assessment of surfactant structures and optimal mixtures for potential use in tertiary flooding strategies in North Sea fields has been examined from fundamental investigations using pure oils. The present study furthermore addresses the physico-chemical problems associated with reservoir oils and how the phase performance of these systems may be correlated with model oils, including the use of toluene and cyclohexane in stock tank oils to produce synthetic live reservoir crudes. Any dependence of surfactant molecular structure on the observed phase properties of proposed oils of equivalent alkane carbon number (EACN) would render simulated live oils as unrepresentative. 

Figure 6. Variation of phase inversion temperature with equivalent alkane carbon number...

It is worth noting that if the two surfactants which are mixed do not share the same value of k, as for instance an alkylbenzene sulfonate (k = 0.16) and an alkylsuhate (k = 0.10), then Eqs. 10-12 have to be divided by k to be expressed in ACN units which have the same meaning in all cases, whatever the k s [33]. The value a/k has been called EPACNUS (Extrapolated Preferred Alkane Carbon Number at Unit Sahnity and no-alcohol), since it is the value of ACN when the conditions S = 1 wt % NaCl,/(A) = 0 and T = 25 °C are satisfied. If the optimiun formulation is determined experimentally, not from the occurrence of three-phase behavior but from the minimum of interfacial tension, as is often the case at low surfactant concentration or when the oil phase is not transparent, it is called EACNmin or Umin [17,34,35]. 

It is worth noting here that this difference between the interface and in the bulk is not specific to surfactant mixtures. While oil mixtures of very similar substances, such as n-alkanes, exhibit a linear mixing rule written in terms of equivalent alkane carbon number or EACN [62-64], mixtures of oils containing substances with very different polarities behave in a non-ideal way and exhibit a segregation near the interface, which results in an accumulation most polar oil components close to the interface [65]. 

Without changing the tuning of the instrument, a compound X is now injected onto the column. The new chromatogram obtained allows the calculation of the Kovats retention index of X on the specific column used. This index is obtained by multiplying the equivalent alkane carbon number that has the same retention time as X by 100. 

In binary systems of a light gas and members of the n-alkane homologuous series in almost all cases type II phase behaviour is found for the lower members of the n-alkane series. With increasing carbon number type IV phase behaviour is found followed by type HI phase behaviour at high carbon numbers. Systems of CO2 + n-alkanes show type II phase behaviour for n-alkane carbon numbers 12, type IV phase behaviour for =13 and type HI phase behaviour for n S14 [11, 12]. This transition from type II to type HI phase behaviour via type IV phase behaviour seems to be the rule, allthough in most binary families type IV phase behaviour is only found at broken values of n in so-called quasi-binary systems [13, 14]. 

Key words hydrophobic oils equivalent alkane carbon number (EACN) surfactant-enhanced remediation... 

Oil contaminants can range in both viscosity and molecular weight. The purpose of this work was to find optimal surfactant formulations to extract low viscosity ( ( 100 cp), high molecular weight (hydrophobic) oils. In surfactant formulation it is common to define the oil molecular weight (hydrophobicity) by virtue of its equivalent alkane carbon number (EACN) aka, how many carbons would there be in an alkane oil of equivalent behavior. Thus, since some crude oils behave similarly to hexane, and since hexane has an alkane carbon number of 6, these crude oils also have an... 

The mixing of a synthetic surfactant and a petroleum soap can be explained in terms of surfactant mixing rules proposed by Wade et al. in 1977 (53). These rules are based on previous studies (54) of the equivalent alkane carbon number (EACN) concept, which show that hydrocarbon behavior toward surfactants is additive and weighted by mole fraction according to the formula ... 

ACN Alkane Carbon Number, see Equivalent Alkane Carbon Number. 

Equivalent Alkane Carbon Number (EACN) Each surfactant or surfactant mixture in a reference series will produce a minimum interfacial tension (IFT) for a different n-alkane. For any crude oil or oil component, a minimum IFT will be observed against one of the reference surfactants. The EACN for the crude oil refers to the n-alkane that would yield minimum... 

Alkane carbon number, equivalent (EACN) definition, 392 equation, 282... 

Figure 2 Isobaric heat capacities (al) and pressure effects on the isobaric heat capacities (a2)for m-cresol. Typical W-shaped excess molar heat capacities (b) at 298.15 K of f 1,4-dioxane-hn-alkanesjmixtures numbers refer to the n-alkane carbon numbers...

It has been established that the behavior of a hydrocarbon in microemulsion formulations can be characterized by its Equivalent Alkane Carbon Number (EACN) (22). This is the number of methylene and methyl carbons making up the molecule. The EACN for MMA should be two and has been determined as such in this laboratory. It is interesting that this correlation seems to apply also to the measured free energies of transfer. This suggests that this previously empirical correlation has a theoretical basis in thermodynamics. Further, in the Li phase, up to a MMA concentration of at least 0.5 M, the free energy of transfer is constant, indicating that the micelle structure is probably not too much different from that at very low MMA concentrations. 

Figure 2. GC-FID chromatograms of reference petroleum products. Numbers indicate n-alkane carbon number represented by the adjacent chromatographic peak. I.S. indicates the position of the internal standeurd (5,a-androstane) chromatographic peak.

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