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Sun L.,Working Station for Postdoctoral Scientific Research in Shengli Oilfield | Spildo K.,University of Bergen | Djurhuus K.,University of Bergen | Skauge A.,University of Bergen
Journal of Dispersion Science and Technology | Year: 2014

A laboratory selection of salinity for a low salinity water-low salinity surfactant (LS-LSS) process is presented in this paper with systematical investigation on surfactant phase behavior, interfacial tension (IFT), and dynamic retention in porous media with IOS2024 and isoamyl alcohol (IAA) as surfactant system. The results show that 0.4 wt% IOS2024 with 1 wt% IAA can provide ultra-low IFT of 10-3 mN/m at around 3000-4000 mg/L total dissolved solids, but at that salinity range the surfactant retention is very high. The search for an optimum surfactant formulation has to consider solution properties and retention in addition to the low IFT. The salinity for a LS-LSS process should thus not be focused on either optimal salinity or ultra-low IFT, but instead the best choice could be a compromise between the properties in question. The three-phase region, where ultra-low IFT are found, is also associated with high retention values. However, we show that as salinity is increased from a two-phase region with oil solubilized in a water continuous microemulsion, there is a region close to the three-phase boundary which has potential. This region does not give ultra-low, but fairly low (10-2 mN/m in this case) interfacial tensions, and also significantly lower retention. © 2014 Copyright Taylor & Francis Group, LLC.

Wang R.,Shandong University | Wang X.,Shandong University | Wang R.,China Research Institute of Daily Chemical Industry | Zheng Y.,Shandong University | And 3 more authors.
Journal of Physical Chemistry B | Year: 2013

The physicochemical properties of the mixed zwitterionic surface activity ionic liquid/anionic surfactant (N-alkyl-N′-carboxymethyl imidazolium inner salts/sodium dodecyl sulfate, [N-C12, N′-CO 2-Im]/SDS) at various molar ratios (R1 = C[N-C12,N′-CO2-Im]/(C[N-C12,N′-CO 2-Im]+ CSDS) were investigated by surface tension and steady-state fluorescence measurements. The results show that the mixed [N-C12, N′-CO2-Im]/SDS system has a much lower cmc value and higher surface activity than individual surfactant. Compared with the mixed zwitterionic betaine surfactant/SDS system, the mixture studied exhibits a stronger synergism, i.e., more negative interaction parameters (βm and βσ). Through addition of NaCl, the wormlike micelles (WMs) could be formed in a [N-C12, N′-CO2-Im]/SDS system. Steady and dynamic rheology was employed to characterize the WMs with different surfactant ratio (R1), NaCl concentration, and temperature. An optimal composition, viz., CT = 60 mM, R1 = 0.45, and CNaCl = 0.10 M, was detected to form the strongest and longest wormlike micelles. Compared with the WMs formed by a traditional zwitterionic C12 betaine/anionic surfactant mixture (e.g., laurylamidopropyl betaine/SDS), the WMs studied have a stronger network structure, which is expected to have potential applications in some fields, such as in nanomaterials synthesis, personal care products, and flooding liquid for tertiary oil recovery. © 2013 American Chemical Society.

Wang X.,Shandong University | Liu J.,Liaocheng University | Yu L.,Shandong University | Jiao J.,Shandong University | And 2 more authors.
Journal of Colloid and Interface Science | Year: 2013

A novel class of zwitterionic surface active ionic liquids (SAILs), N-alkyl-N'-carboxymethyl imidazolium inner salts ([NC n, N'CO 2Im], n=10, 12, 14), was synthesized. Their aggregation behavior in aqueous solution was investigated by surface tension, isothermal titration calorimetry, and steady-state fluorescence. Compared with the reported imidazolium-based cationic SAILs, 1-alkyl-3-methylimidazolium bromide ([C nmim]Br) and zwitterionic betaine surfactants, (C nH 2n+1N(CH 3) 2CH 2COO -), [NC n, N'CO 2Im] exhibits significantly lower critical micelle concentration (cmc) and surface tension at cmc (γ cmc) values. It is attributed to the incorporation of a deprotonated carboxylic group into the head group, which weakens the electrostatic repulsion between head groups and favors micellization. The micellar aggregation number of [NC n, N'CO 2Im] is larger than that of [C nmim]Br, while less than that of C nH 2n+1N(CH 3) 2CH 2COO -. Similar to the traditional zwitterionic surfactants, the surface activity and adsorption properties of [NC 12, N'CO 2Im] at air/water interface have a slight variation with temperature, pH, and ionic strength. This indicates that the present zwitterionic SAILs display the aggregation behavior much similar to zwitterionic surfactants, distinctly different from imidazolium-based cationic SAILs. Sets in low sensitivity to the environmental conditions, superior surface activity and unique physicochemical properties of ionic liquids, [NC n, N'CO 2Im] can be exploited for utilizing as a potential substitute for conventional surfactants in certain fields. © 2012 Elsevier Inc.

Zhao Y.,Shandong University | Du W.,Shandong University | Sun L.,Working Station for Postdoctoral Scientific Research in Shengli Oilfield | Yu L.,Shandong University | And 2 more authors.
Colloid and Polymer Science | Year: 2013

Calcium carbonate (CaCO3) nanocrystals with controllable polymorph and morphology have been successfully synthesized with the aid of an effective control agent, a halogen-free, low-cost ionic liquid surfactant, 1-butyl-3-methylimidazolium dodecylsulfate ([C4mim][C 12SO4]) in a supersaturated aqueous solution. For the first time, facile preparation of pure lens-like vaterite, sheet-like calcite, and peanut-like aragonite was all achieved in the [C4mim][C 12SO4] aqueous solution through changing the concentration, temperature, and initial pH value and adding magnesium ions. Washed by water and ethanol, all the aggregates were free of [C 4mim][C12SO4] and can be stable at least 1 month in air. The crystal form of the aggregates changed from pure calcite to pure vaterite at room temperature only through increasing [C4mim] [C12SO4] concentration. Formation of the ordered CaCO 3 structures is mainly ascribed to the aggregation of the primary nanoparticles whose formation mechanism is related to the change of supersaturation. This study can provide a facile and environment-friendly method to fabricate CaCO3 crystal aggregates with various morphologies and polymorphs and can be used for large-scale industrial production and biomimetic synthesis. © 2013 Springer-Verlag Berlin Heidelberg.

Jiao J.,Shandong University | Zhang Y.,Shandong University | Fang L.,Shandong University | Yu L.,Shandong University | And 3 more authors.
Journal of Colloid and Interface Science | Year: 2013

Effect of three inorganic electrolytes (LiCl, NaCl, and MgCl2) and four organic electrolytes, viz. tetraalkylammonium bromides ((CH3)4NBr, (C2H5)4NBr, (C3H7)4NBr, and (C4H9)4NBr) on the aggregation behavior of the anionic halogen-free surface active ionic liquid, 1-butyl-3-methylimidazolium dodecylsulfate ([C4mim][C12SO4]), in aqueous solution was studied by surface tension, steady-state fluorescence quenching, and dynamic light scattering measurements. The results show that all the electrolytes investigated have a salting-out effect, which promotes aggregate formation of [C4mim][C12SO4]. The stronger hydrophobicity of organic electrolytes is crucial for the superior influence on the surface activity of [C4mim][C12SO4]. However, the stabilization energy results obtained by quantum chemical calculations prove that although the promoting effect of organic cations (tetraalkylammonium cations) on the micellization process of [C4mim][C12SO4] is powerful, they mainly act as counterions. For a given electrolyte (i.e., NaCl), critical micelle concentration of [C4mim][C12SO4] decreases with increasing electrolyte concentration. The average aggregation number and aggregate size of [C4mim][C12SO4] were shown to change slightly in the presence of various electrolytes, except for MgCl2. Anyway, hydrophobicity together with bulkiness and hydration ability of cations of the added electrolytes are suggested to play important roles in modifying the aggregation behavior of [C4mim][C12SO4] in aqueous solution. © 2013 Elsevier Inc.

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