Differential viability of allelic isozymes in the marine gastropod Cerithium scabridum exposed to the environmental stress of nonionic detergent and crude oil-surfactant mixtures

Genetica ◽  
1988 ◽  
Vol 78 (3) ◽  
pp. 205-213 ◽  
Author(s):  
E. Nevo ◽  
B. Lavie
Keyword(s):  
Environmental Stress ◽  
Crude Oil ◽  
Surfactant Mixtures ◽  
Marine Gastropod ◽  
Nonionic Detergent ◽  
Differential Viability ◽  
Allelic Isozymes

Low Interfacial Tensions Involving Mixtures of Surfactants

1977 ◽  
Vol 17 (02) ◽  
pp. 122-128 ◽  
Author(s):  
W.H. Wade ◽  
J.C. Morgan ◽  
J.K. Jacobson ◽  
R.S. Schechter
Keyword(s):  
Interfacial Tension ◽  
Crude Oil ◽  
Surfactant Concentration ◽  
Electrolyte Concentration ◽  
Hydrocarbon Mixture ◽  
Surfactant Mixtures ◽  
Interfacial Tensions ◽  
System Variables ◽  
Low Tension ◽  
Scaling Rule

Abstract The interfacial tension of surfactant mixtures with hydrocarbons obeys a simple scaling rule. Many apparently inert surfactants give low tensions when in mixtures; the scaling rule still applies to these mixtures. The influence of surfactant structure and molecular weight on low-tension behavior is examined, and the application of these results to the optimization of surfactant flooding systems is discussed. Introduction It has been shown that the interfacial-tension behavior of a given crude oil with a surfactant solution of the sulfonate type may be modeled by replacing the crude oil with one particular alkane. The number of carbon atoms in the alkane is referred to as the equivalent alkane carbon number (EACN) of the crude oil, and this EACN is independent of the surfactant used (at fixed standard conditions). This equivalency of a crude oil and an alkane is a result of the simple averaging behavior of hydrocarbons when mixed. Any hydrocarbon may be assigned an EACN value. For instance, when homologous series of alkyl benzenes and alkanes are run against the petroleum sulfonate TRS 10-80 at 2 gm/liter of surfactant with 10 gm/liter NaCl present, heptyl benzene and heptane, respectively, give minimum interfacial tensions, a. The EACN of heptyl benzene is 7, since it is equivalent to heptane. A simple averaging rule will give the EACN of a hydrocarbon mixture : (1) where x is the mole fraction of the ith component. Thus, an equimolar mixture of undecane (EACN 11) and heptyl benzene (EACN 7) has an EACN of 9. If a surfactant gives a low (minimum) sigma against nonane (EACN 9), it will also give a low sigma against the above mixture. Eq. 1 implies that a crude oil, which is a multicomponent hydrocarbon mixture, may be assigned an EACN. This has been verified experimentally. For example, Big Muddy field crude oil has an EACN of 8.5. Therefore, any surfactant phase giving a minimum tension against an equimolar mixture of octane and nonane gives a low tension against Big Muddy crude. All crude oils rested to date have EACN's ranging from 6 to 9. For a given surfactant, the alkane of minimum tension (min) may be affected by the electrolyte concentration or type, the temperature, the surfactant concentration, or the presence of a cosurfactant. These system variables may be adjusted until the nmin for a surfactant matches exactly the EACN of a crude oil. For any particular surfactant, many different combinations of variables will give the same n min value; therefore, there are many possible systems, each with n = EACN, available for crude oil recovery. In practice, however, the system variables may be manipulated to a limited extent only. The temperature of an oil field is fixed, and the surfactant concentration is limited by considerations of solubility and expense. The electrolyte concentration and type is partly determined by oilfield conditions and is limited by the effect on surfactant solubility. These limitations mean that many of the surfactants presently available on a large enough scale for use in low-tension flooding will not give minimum tensions in the range required (n of 6 to 9). This paper shows how minimal sigma's in the required range may be found for some of these "off-scale" surfactants when they are used in surfactant mixtures. The hypothesis tested here is that surfactant mixtures average in a manner analogous to the averaging of hydrocarbons in the oil phase. It will be shown that each surfactant component may be assigned an n value and that the alkane of minimum tension of a mixture of surfactants, (n), is then given by (2) where x is now the mole fraction of the ith component of the surfactant mixture. This greatly extends the number of surfactants that may be considered as candidates for use in low interfacial-tension flooding. SPEJ P. 122

scholarly journals Effects of Surfactant Mixtures, Including Corexit 9527, on Bacterial Oxidation of Acetate and Alkanes in Crude Oil

1999 ◽  
Vol 65 (4) ◽  
pp. 1658-1661 ◽  
Author(s):  
Per Bruheim ◽  
Harald Bredholt ◽  
Kjell Eimhjellen
Keyword(s):  
Crude Oil ◽  
Oxidation Rate ◽  
Acinetobacter Calcoaceticus ◽  
Alkane Oxidation ◽  
Uptake System ◽  
Surfactant Mixtures ◽  
Bacterial Oxidation ◽  
Acetate Uptake ◽  
Negative Effect ◽  
Span 80

ABSTRACT Mixtures of nonionic and anionic surfactants, including Corexit 9527, were tested to determine their effects on bacterial oxidation of acetate and alkanes in crude oil by cells pregrown on these substrates. Corexit 9527 inhibited oxidation of the alkanes in crude oil byAcinetobacter calcoaceticus ATCC 31012, while Span 80, a Corexit 9527 constituent, markedly increased the oil oxidation rate. Another Corexit 9527 constituent, the negatively charged dioctyl sulfosuccinate (AOT), strongly reduced the oxidation rate. The combination of Span 80 and AOT increased the rate, but not as much as Span 80 alone increased it, which tentatively explained the negative effect of Corexit 9527. The results of acetate uptake and oxidation experiments indicated that the nonionic surfactants interacted with the acetate uptake system while the anionic surfactant interacted with the oxidation system of the bacteria. The overall effect of Corexit 9527 on alkane oxidation by A. calcoaceticus ATCC 31012 thus seems to be the sum of the independent effects of the individual surfactants in the surfactant mixture. When Rhodococcus sp. strain 094 was used, the alkane oxidation rate decreased to almost zero in the presence of a mixture of Tergitol 15-S-7 and AOT even though the Tergitol 15-S-7 surfactant increased the alkane oxidation rate and AOT did not affect it. This indicated that there was synergism between the two surfactants rather than an additive effect like that observed forA. calcoaceticus ATCC 31012.

Oil-Recovery Surfactant Formulation Development Using Surface Design Experiments

1982 ◽  
Vol 22 (02) ◽  
pp. 237-244 ◽  
Author(s):  
W. Gerbacia ◽  
T.J. McMillen
Keyword(s):  
Crude Oil ◽  
Aqueous Phase ◽  
Oil Recovery ◽  
Weight Ratio ◽  
Equivalent Weight ◽  
Formulation Development ◽  
Surfactant Mixtures ◽  
Surface Design ◽  
Oil Displacement ◽  
Surface Active

Abstract Experiments were conducted to study the effects of three surfactant flooding variables on oil recovery and interfacial tension (IFT). The variables studied were the fraction of high-equivalent-weight sulfonate, the cosurfactant hydrophile-lipophile balance (HLB), and the weight ratio of cosurfactant to sulfonate. We then evaluated the data statistically, obtaining optimal formulations for this data space. From trends observed in the investigation, a high crude-oil recovery formulation was developed for this crude-oil/brine system. All three variables had a significant effect on oil displacement. The high-equivalent-weight sulfonate was detrimental to recovery of the crude oil used in this investigation. Systems with low measured interfacial tensions did not produce the highest recoveries. This is explained by extraneous dominating effects. Introduction We undertook this investigation to evaluate the effects of three controlled variables on the recovery of a California crude oil by surfactant dispersions. Additional goals were to develop an acceptable qualitative relationship between these variables and the uncontrolled variables of displacement efficiency (ED) and IFT. The controlled variables werethe fraction of high-equivalent-weight sulfonate in the surfactant mixture (F512),the cosurfactant HLB, andthe weight ratio of cosurfactant to surfactant (R). The properties of oil/aqueous sulfonate solution interfaces are affected by the equivalent weight of the sulfonate. The characteristics of these interfaces are important in achieving high oil-displacement efficiencies. For a homologous series, surfactant partitioning among the aqueous phase, the oil phase, and the interface changes as the equivalent-weight range of the sulfonate varies. Low-equivalent-weight sulfonates partition preferentially to the aqueous phase. However as the hydrophobic part of the sulfonate molecule is increased in site (in relation to the hydrophilic pan) partitioning shirts increasingly to the interface, and eventually to the oil phase. The surfactant is most surface-active during the intermediate stages. This is one reason for the IFT minima often observed after changes in HLB of the surfactant, or in the properties of the oil or water. All these variables can affect partitioning. The interfacial and bulk properties of surfactant mixtures are modified by cosurfactants. These are surface-active chemicals that usually are present in smaller amounts than the primary surfactant(s). Typically, cosurfactants are less surface-active than the primary surfactant. In many cases, changes in the cosurfactant/surfactant ratio can alter the colloidal properties of surfactant dispersions drastically. IFT is also sensitive to this ratio. For this reason, we examined the ratio rather than the cosurfactant concentration. The uncontrolled variables measured were ED and IFT. The literature states that these should be related, but the question remains as to which IFT should be measured: the equilibrium value, some time- or concentration-dependent function, or some other function? Gal and Sandvik used the IFT's of the effluent fluids. Healy et al. used equilibrium measurements of influent fluids. We used equilibrium values for the fluids before flooding, as did Healy et al. As will be seen, these proved unsatisfactory. A rotatable-response surface design was used to define the selected combinations of controlled variables. Our rationale for using statistically designed experiments is to simplify data analysis and to isolate variable effects. In this way, we can observe trends that may lead to high-displacement formulations. SPEJ P. 237^

Phase behavior of cationic and anionic surfactants at low concentrations

1992 ◽  
Vol 50 (1) ◽  
pp. 694-695
Author(s):  
E. Naranjo
Keyword(s):  
Phase Behavior ◽  
Structural Characterization ◽  
Dynamic Systems ◽  
Anionic Surfactants ◽  
Intermolecular Forces ◽  
Stable Form ◽  
Surfactant Mixtures ◽  
Low Concentrations ◽  
Cationic And Anionic Surfactants ◽  
General Method

Equilibrium vesicles, those which are the stable form of aggregation and form spontaneously on mixing surfactant with water, have never been demonstrated in single component bilayers and only rarely in lipid or surfactant mixtures. Designing a simple and general method for producing spontaneous and stable vesicles depends on a better understanding of the thermodynamics of aggregation, the interplay of intermolecular forces in surfactants, and an efficient way of doing structural characterization in dynamic systems.

A comparison of the Stroop Test to other tasks for studies of environmental stress.

1981 ◽  
Author(s):  
Mary M. Harbeson ◽  
Robert S. Kennedy ◽  
Alvah C. Bittner
Keyword(s):  
Environmental Stress ◽  
Stroop Test
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