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In order to solve the problem that the influence of reservoir characteristics on the test results of air foam flooding, the mechanism of rhythmicity, heterogeneity and channeling of reservoir was studied by means of reservoir numerical simulation. The results show that: (1) in positive prosody reservoir, the recovery efficiency of the air foam flooding test is the most significant. (2) when the permeability difference of the reservoir is between 4 and 30, the effect of air foam flooding is better. (3) foam has a certain blocking effect on channeling channel, but when the permeability of channeling channel is greater than 3000 mD, the blocking effect is limited. It has important guiding significance for improving the effect of foam assisted deaeration air flooding test and promoting its application.

The micellization behavior of the ternary mixture of an amphoteric sodium 3-(N-dodecyl ethylenediamino)-2-hydropropyl sulfonate (C12AS) with two nonionic surfactants, octylphenol polyoxyethylene ether (OP-n, where n is the number of hydrophilic unit oxyethylene glycol ethers, n = 4, 7, 10), was investigated using both the tensiometry and the 1H NMR technique. Also, the effect of the addition of nonionic surfactant with a longer or shorter hydrophilic chain, e.g., OP-10 or OP-4, on the micellization of the binary mixture of C12AS/OP-7 with a maximum synergism was probed. Based on the regular solution theory, thermodynamic models were adopted to obtain the composition, activity coefficient of mixed micelle and some thermodynamic parameters. The addition of OP-10 or OP-4 into the binary mixture of C12AS/OP-7 induces the change in the mixed critical micelle concentration, which can be explained by the change in the composition of mixed micelle and the effect of hydrophilic chain. Thermodynamic data show that the addition of OP-10 or OP-4 results in the change from the enthalpy overwhelming process of micellization to the entropy-driven process. The chemical shift of proton in the terminal hydroxy group of OP-n in binary or ternary surfactant mixture is also adopted to describe the obtained results. The findings will help with understanding the interaction behavior between molecules in the multicomponent mixture, especially, the effect of the addition of homologues or other components on the properties of surfactant formulation.

The micellization behavior of the mixed system of amphoteric sodium 3-(N-dodecyl ethylenediamino)-2-hydropropyl sulfonate (C12AS) and cationic octadecyltrimethyl ammonium bromide (OTAB) in ...

A systematic investigation of the effect of isopropanol (IPA) on the micellization of binary mixtures of an amphoteric surfactant, sodium 3-(N-dodecyl ethylenediamino)-2-hydroxypropyl sulfonate (C12AS), with a nonionic surfactant, octylphenol polyoxyethylene ether having seven oxyethylene glycol ether (OP-7), the interaction between them, and thermodynamic parameters was performed in the water-IPA mixed solvent media (the concentration of IPA in bulk solution is within the range of 0 to 100 g/L) at 25 ± 0.2 °C. The values of critical micelle concentration (cmc) of individual surfactants and their mixtures were determined by both the tensiometry and the UV–vis spectrometry. According to the pseudophase separation and other theromdynamic models (including Clint's model, Rubingh's model, Maeda's model, etc.), molar fractions of components and activity coefficients in mixed micelle, interaction parameters between two surfactants, and thermodynamic parameters were calculated from the corresponding relationships. The variation of the cmc and the micellization parameters with the concentration of IPA can be explained by the structure-breaking ability of IPA and the change in the conformation of C12AS. The synergistic effect between two surfactants can be observed and has a strong dependence on the concentration of IPA. Thermodynamic data show that the micellization for the C12AS/OP-7 mixture is a entropy-driven spontaneous process. The addition of IPA is a disadvantage to the formation of mixed micelle. In comparison with the case in aqueous solution without IPA, the presence of IPA causes a remarkable contribution of entropy to the process of micellization and the contribution increases with the concentration of IPA.

The interaction behavior and the process of mixed micellization for binary mixtures of an amino sulfonate amphoteric surfactant sodium 3-(N-dodecyl ethylenediamino)-2-hydropropyl sulfonate (C12AS) and a cationic surfactant octadecyltrimethylammonium bromide (OTAB) in aqueous solution of NaCl (0.250 M) at 313.15 K were investigated using both the tensiometry and the UV–vis spectrometry using pyrene as a probe. The mixed critical micelle concentration (cmc) of the C12AS/OTAB mixtures were determined by two techniques. Based on regular solution theory, pseudophase separation model, Clint’s model, Rosen’s model, and Rubingh’s model, some parameters (including the ideal mixed cmc, the compositions in mixed micelle, the interaction parameters between two surfactants, the activity coefficients in mixed micelle, some thermodynamic parameters, etc.) were evaluated and calculated. The deviation of mixed cmc from its ideal value indicates a nonideal mixing between two surfactants. In comparison with those in aqueous...

The micellization behaviors of binary mixtures constituted by an amphoteric surfactant, sodium 3-(N-dodecyl ethylenediamino)-2-hydropropyl sulfonate, and a nonionic surfactant octylphenol polyoxyethylene ether (10), OP-10, in aqueous solutions containing seven inorganic salts were investigated. The values of mixed critical micelle concentration (cmcM) were determined by both the tensiometry and the UV–vis spectroscopy method using pyrene as a probe. The dependence of cmcM on inorganic salt was established. According to different theoretical models, the components in mixed micelle, interaction parameters between two surfactants, etc. were obtained. Upon adding inorganic salt, the component in real mixed micelle is inferior to the ideal case, indicating nonideal mixing. Different inorganic salts result in the variation of component in mixed micelle. For all mixed surfactant systems, a negative interaction parameter between surfactants shows synergistic effect. Thermodynamic parameters show that the process ...

The interaction mechanism of multiple quaternary ammonium salts (MQAS) with bovine serum albumin (BSA) was examined by the fluorescence quenching method and circular dichroism (CD) spectra. Moreover, the effects of MQAS on the dynamic properties of BSA adsorption layers at different pH values were investigated using dilational interfacial rheology. Results show that the quenching constants increase with an increase in pH values and decrease with an increase in the experiment temperature at pH 5.3. The quenching mechanism is static quenching, and the electrostatic force dominates the interaction between MQAS and BSA at pH 5.3. Due to three positive head groups, MQAS can significantly affect the dynamic interfacial activity of BSA molecules at a relatively low concentration. At pH 4.3, the electrostatic repulsion is unfavorable for the formation of MQAS/BSA complexes. Consequently, MQAS molecules will replace BSA molecules from the interface by competitive adsorption. At the pH value above the isoelectric point of BSA, the electrostatic attraction is better for the formation of MQAS/BSA complexes, which exhibit a rapid adsorption rate and an enhanced interfacial activity. Moreover, the kinetic dependencies of interfacial dilational elasticity for the MQAS/BSA mixtures become nonmonotonous. The appearance of the maximum interfacial elasticity values can be attributed to the formation of tails and loops, which suggests that the addition of MQAS destroys the secondary and tertiary structure of protein in the bulk phase. In addition, the effects of MQAS on the secondary structure of protein were demonstrated by CD spectra.

In aqueous solutions containing isopropanol (IPA), within the range of 0–100 g/L, the micellization behaviors of binary surfactant mixtures of amphoteric sodium 3-( N -dodecyl ethylenediamino)-2-hydropropyl sulfonate (C12AS) and cationic octadecyltrimethyl ammonium bromide (OTAB) were investigated by three techniques including tensiometry, conductometry and isothermal titration microcalorimetry (ITC). Based on extant theories and models (such as, the regular solution theory, the pseudophase separation model, the Rubingh’s model, etc.), the effects of IPA on the molar fraction of components in mixed micelles, the interaction parameters between the two surfactants, and associated thermodynamic parameters have been discussed. The addition of cosolvent IPA results in a change in the conformation of C12AS, as well as affecting the interaction behavior between the two surfactants and a decrease in the hydrophobic effect. The synergistic effects between the two surfactants varies partly with the concentration of IPA. The observations can be used to explain the cause for the abnormal dependence of the molar fraction of components in mixed micelles and the interaction parameters on the concentration of the cosolvent IPA. Thermodynamic parameters further show the effect of IPA on the entropy-driven process of micellization.

The effect of isopropanol (IPA) on the micellization behavior of binary surfactant mixtures of an amphoteric sodium 3-( N -dodecyl ethylenediamino)-2-hydropropyl sulfonate (C12AS) with an anionic sodium dodecylbenzene sulfonate (SDBS) was investigated in the water–IPA mixed solvent media (the concentration of IPA in bulk solution varies within the range of 0–100 g/L). The values of critical micelle concentration ( cmc ) of individual surfactants and their mixtures were determined by both the conductometry and the UV–vis spectrometry. Based on the regular solution theory, pseudophase separation model, and some thermodynamic models, the effect of IPA on the micellization parameters and the thermodynamic parameters was theoretically discussed. The addition of IPA in aqueous solution not only changes the polar of solution but also influences the solvation of ionic surfactant, consequently resulting in the change in the mixed cmc values and the molar fraction of components in mixed micelle. The synergistic effect between two surfactants may be decreased with increasing IPA. Thermodynamic data show that the presence of IPA may be not an advantage to the spontaneous process of micellization, and influences the contribution of entropy in the process of micellization. Specially, these cases can be obviously observed at a high concentration of IPA in aqueous solution. These results help us to understand the advantage and the disadvantage of the effect of cosolvent (specially IPA) on the micellization of mixed surfactants and to design the surfactant formulas relative to cosolvent.

The effect of different valent inorganic cations and the hydrophilic group of surfactant on the micellization behavior of binary surfactant mixtures constituted by an amphoteric surfactant, sodium 3-(N-dodecyl ethylenediamino)-2-hydropropyl sulfonate (C12AS), and three nonionic surfactants octylphenol polyoxyethylene ether (OP-n) with different numbers of oxyethylene glycol ethers (n), namely, OP-10, OP-7, and OP-4 was investigated in aqueous solution. These inorganic cations include Na+, K+, Mg2+, Ca2+, Ba2+, Al3+ and Fe3+. Both the tensiometry and the UV–vis spectrophotometry using pyrene as a probe were adopted to determine the critical micelle concentrations (cmc) of individual or mixed surfactants. Interaction parameters between two surfactants and other parameters were obtained based on the regular solution theory, the pseudophase separation model, Rubingh's model, etc. Thermodynamic parameters including Gibbs energy of micellization and thermodynamic stability were also calculated by both the equation proposed by Molyneux et al. and Maeda's treatment, respectively. The effect of different valent cations on both the mixed cmc of surfactant mixtures and the molar fraction of C12AS in mixed micelle (X1) can be explained theoretically by the salting-out effect, electrostatic interaction and steric effect. For three binary surfactant mixtures, the chain length of hydrophilic group of surfactant results in different micellization behaviors. On adding salts, the interaction parameters show that there exists a synergistic effect between two surfactants, and the effect increases with increasing the ratio of valence (Z) and atom radius (R) of cation, especially, for the C12AS/OP-4 mixture. With increasing the Z/R value of cation, a deviation of X1 from the ideal value shows a divergence for three binary surfactant mixtures because of different hydrophilicities of surfactant. Thermodynamic parameters indicate that the addition of cations with a large Z/R value can be contributive more effectively to the formation of stable mixed micelle than the case in the presence of cations with a small Z/R value.

In aqueous solution at 40 °C, the micellization behavior of the binary mixtures constituted by an amphoteric sodium n-dodecyl diamine sulfonate and a cationic octadecyltrimethyl ammonium bromide has been investigated by the tensiometric technology. The values of critical micelle concentration (cmc) were determined by surface tension measurement of aqueous solution. The experimental data were analyzed according to various mixing thermodynamic models within the framework of the pseudophase separation model. The values of mixed cmc have been predicted successfully by both the Rubingh’s and Rodenas’s treatments. Various parameters like the mixed cmc, interaction parameters between surfactants (β12), the compositions and activity coefficients in mixed micelles as well as thermodynamic properties have been determined using Lang, Rubingh, Rodenas, and Rosen approach. Over the entire composition range investigated, the mixed micelle formation, non-ideal or ideal mixing, and synergistic effect or antagonism are explained by the electrostatic interaction between ionic headgroups of surfactants and the steric effect of surfactant. Thermodynamic parameters favor the process of micellization which is found to be entropy-driven.

A surface properties of a sulfobetaine–type zwitterionic gemini surfactant with the structure of 1,2-bis [N-methyl-N-(3-sulfopropyl) -dodecylammonium] ethane betaine (ZGS12), were investigated in aqueous solution . The critical micelle concentration (CMC) of the gemini surfactant at different temperatures and mixed micelle properties of ZGS12 and sodium dodecyl benzene sulfonate (SDBS) were investigated. The results show that cmc of the gemini surfactant (ZGS12) decreases with raising temperature, Gibbs free energy changes and entropy changes are negative and postive, respectively, indicating the formation of micelle is spontaneous and driven mainly by entropy. According to the theory of regular solution , interaction parameters between the zwitterionic gemini surfactant ZGS12 and the anionic surfactant SDBS indicate strong attractive interaction and great degree of synergism in micelle formation due to weakening of the electrostatic head group repulsion.

A novel ultraviolet absorption spectrometry method was developed for the quantitative determination of HABS by adding β-cyclodextrin with the molar ratio of 1:1 in strong interference aqueous solution. The results indicated that the effect of several common interfering flooding agents (SAS, OP-10, HPAM) on the determination of HABS could be greatly reduced in β- cyclodextrin aqueous solution. Thus, the determination errors of the determined HABS were less than 2.0% under strong inter- ference, and the detection limit (S/N==3) of the method could be also as high was 8.3-9.1 x 10(-4) mg · L(-1). Various characterization results including 1H-NMR, TG-DSC and FTIR showed the interaction between β-cyclodextrin and HABS. The results of H-NMR analysis showed that HABS molecule could enter into the interior of the cavity of β-cyclodextrin molecule. TG-DSC analysis exhibited that the stable inclusion of β-cyclodextrin and HABS could be automatically formed. The interactions between the functional groups of β-cyclodextrin and HABS were showed by FTIR analysis, which also exhibited that the stable inclusion could be formed by HABS entering from the narrow or the broad mouth of the β-cyclodextrin. The interference of the UV spectrum of HABS could be reduced by β-cyclodextrin since the interaction between β-cyclodextrin due to the interaction between β-cyclodextrin and HABS in the inclusion complex.