Novel Surfactant for the Reduction of CO2/Brine Interfacial Tension

The synthesis of novel CO₂ philic surfactant using maleic anhydride and dipropylene tertiary butyl alcohol is reported. The synthesis involved the esterification of maleic anhydride to produce bis(2-(2-(tert-butoxy)propoxy)propyl) maleate and subsequent sulfonation of the esterified product. Para toluene sulfonic acid was employed as catalyst for the esterification reaction. The esterification reaction was optimized for the maximum yield of 98% of bis(2-(2-(tert-butoxy)propoxy)propyl) maleate. The esterification reaction kinetics employing heterogeneous catalyst were also studied. Although this is a bimolecular reaction, a first order reaction kinetics with respect to acid has been observed. The activation energy was found to be 58.71 kJ/mol. The diester was followed by the sulfonation process and a yield of 85% of surfactant was achieved. The synthesized surfactant successfully lowered down the IFT between CO_2/brine to 1.93 mN/m. This surfactant has a great potential to be used for CO₂-EOR applications.     

Synthesis of a New CO2 Philic Surfactant for Enhanced Oil Recovery Applications

The synthesis of CO₂ philic surfactant using maleic anhydride and 4-tert-butylbenzyl alcohol is reported. We reacted maleic anhydride with 4-tert-butylbenzyl alcohol to form bis(4-(tert-butyl)benzyl) fumarate and sulfonated the produced diester. The esterification reaction was optimized for a maximum yield of 98% of bis(4-(tert-butyl)benzyl) fumarate. First-order reaction kinetics with respect to acid was observed. The activation energy was found to be 55.62 kJ/mol. The sulfonated product of diester was obtained by the sulfonation reaction and the yield of 82% of surfactant was achieved. The in-house developed surfactant effectively lowered down the IFT between CO_2/brine to 4.2 mN/m. This surfactant is targeted for CO₂-EOR applications.     

阴阳离子表面活性剂体系超低油水界面张力的应用

通过阴阳离子表面活性剂复配,在实际油水体系中获得了超低界面张力.通过在阴离子表面活性剂分子结构中加入乙氧基(EO)链段,以及采用阴阳离子加非离子型表面活性剂的三组分策略,有效解决了混合表面活性剂在水溶液中溶解度问题.进而研究了阳离子表面活性剂结构、非离子表面活性剂结构、三者组分配比、表面活性剂总浓度等因素对油水界面张力的影响,从而在胜利油田多个实际油水体系中获得了较大比例范围和较低浓度区域的油水超低界面张力,部分体系甚至达到了10-4 mN·m-1.由于阴阳离子表面活性剂间强烈的静电吸引作用,相关体系具有很好的抗吸附能力.经过石英砂48 h吸附后,体系仍然具有很好的超低界面张力.     

ASP复合驱油体系瞬时界面张力的研究

以胜利油田孤岛试验区原油为油相,用正交试验筛选了碱/天然混合羧酸盐/聚合物驱油体系,讨论了各组分对ASP复合驱油体系油水瞬时界面张力的影响,并探讨了各组分间的相互作用机理及其在油水界面的吸附机理。     

Modeling Interfacial Tension of n-Alkane/Water-Salt System Using Artificial Neural Networks

In this paper, a feed forward neural network is built and trained using experimental data reported in the literature to model interfacial tension of n-alkane/water-salt systems. Temperature, pressure, molecular weight of n-alkane, and ionic strength of electrolyte solution are used as input to the neural network. The model succeeded to predict interfacial tension of liquid n-alkane/water system with or without the presence of electrolyte and yielded average absolute deviation of 0.58% over all data points. The performance of the model is analyzed and compared against the performance of the other alternative models. It was found out that the proposed model outperforms the other alternatives.     

表面活性剂溶液动态表面张力及吸附动力学研究

本文简介了动态表面张力的定义、测定方法及吸附动力学,对非离子、阴离子、阳离子及两性表面活性剂溶液动态表面张力的研究情况进行了总结,重点讨论了浓度、温度、添加剂及化学结构因素对动态表面张力的影响.     

Investigation Static/Dynamic Surface and Interfacial Tension of Some Synthesized Polymeric Surfactants to Enhance the Egyptian Jet Fuel A1 Atomization

In the present work some exthoxylated polyalkylphenol surfactants have different alkyl chains (nonyl and dodecyl) were synthesized. The static surface tension for these surfactants in water and jet fuel A1 was measured and the critical micelle concentration (CMC) for each surfactant was determined. The data show the general trend of decreasing the CMC against the molecular weight of the synthesized polymeric surfactants. The HLB of these surfactants was also calculated. The dynamic surface tension for the synthesized surfactants was measured at CMC. The dynamic interfacial tension for these surfactants with jet fuel A1 at CMC was also measured using the spinning drop technique. The results showed that the effect of the synthesized surfactants on deceasing the time of droplet maturation was significant remarked. The decrease of this time leads to enhance of jet fuel atomization.     

Interfacial Tension of Polyethylene Glycol/Potassium Phosphate Aqueous Two-Phase Systems

Abstract

The interfacial tension of Polyethylene glycol (PEG)/potassium phosphate two-phase systems was measured by the rotating drop method. The interfacial tension was as low as 0.001 dyne/cm and increased with increases in the total concentrations of both PEG and potassium phosphate in two-phase systems. The increase in the interfacial tension was a function of the concentration differences of PEG and potassium phosphate between the top and the bottom phases which was confirmed by the tie line analysis. The interfacial tension was affected also by the molecular weigth of PEG. At low PEG molecular weights, the increase in the molecular weight greatly increased the interfacial tension, but at high molecular weights, the interfacial tension varied less with the molecular weight.     

DTAB降低饱和烷烃与水的界面张力的研究

判断一种表面活性剂降低油-水界面张力性能的优劣,就需要对界面张力进行准确有效的测量。文章就不同浓度的十二烷基三甲基溴化铵(DTAB)水溶液分别与正庚烷(n-Heptane)和正十六烷(n-Hexadecane)之间的界面张力进行定量的测量,分别得到了在30℃下水-正庚烷和水-正十六烷体系的界面张力随DTAB浓度变化的曲线。结果表明,在DTAB浓度达到其所在体系中的CMC值时,水-正庚烷体系界面张力小于水-十六烷体系界面张力。DTAB具有较强的抗矿盐能力,界面张力随温度升高有所下降。     

阴阳离子表面活性剂混合体系在克拉玛依油田中获得超低界面张力

利用阴阳离子表面活性剂复配技术,在克拉玛依油田实际油水体系中获得了超低界面张力.通过添加非离子保护剂的第三组分,阴阳离子表面活性剂混合体系在克拉玛依油田回注水体系中的溶解度大大提高.确定了相关体系能够获得超低界面张力的表面活性剂的浓度和混合的比例范围,在克拉玛依油田的多个实际油水体系中获得了具有较大复配比例和较低表面活性剂浓度的实际配方,其中部分体系油水界面张力可接近10-4mN·m-1.同时,这类阴阳离子表面活性剂混合体系具有很好的抗吸附能力,在石英砂吸附72 h后体系依然呈现优良的超低界面张力.     

Kinetics and Equilibria of Synthesized Anionic Surfactant onto Berea Sandstone

We present static adsorption studies of anionic surfactants on crushed Berea sandstone. The maximum adsorption density was 0.9604 mg/g. The kinetics of adsorption process was modeled using pseudo-first-order and pseudo-second-order rate equations at 25°C and 70°C. The equilibrium adsorption process was validated using Langmuir and Freundlich adsorption models. In addition, the effects of different parameters that govern the effectiveness of these surfactants such as pH and temperature were also investigated. The kinetic study results show that the surfactant adsorption is a time dependent process. The apparent rate constant of adsorption process determined by the first-order kinetic model at 25°C and 70°C were 0.11768 and ?0.04513, respectively. The rate constant for pseudo-second-order kinetic model was 0.0086 at 25°C and 0.0101 at 70°C. The adsorption of anionic surfactant followed pseudo-second-order kinetic model. The Freundlich and Langmuir model constant were 1.6509 × 10^?4 and ?9.775 × 10^?5, respectively. The equilibrium results showed that the adsorption of anionic surfactant onto Berea sandstone was well described by Langmuir adsorption model. It was concluded that anionic surfactants performed better at higher pH and temperature.      

The Interfacial Tension and Alkane Carbon Number (nmin) of Alkyl Benzene Sulfonates in Relation to Enhanced Oil Recovery. Part I: Effect of Surfactant Molecular Weight/Temperature and Electrolyte on nmin

Twelve anionic monoisomeric surfactants based on the alkyl benzene sulfonic acid were prepared. In two sets of experiments, the (n_min) values were determined at 28 and 70°C for them. The n-hydrocarbon scans (n-C₅ to n-C₁₈) against the interfacial tension were used to determine the (n_min) values. The factors affecting (n_min) such as; molecular weight, branching of side chain, temperature and electrolyte addition were investigated. From the obtained results, it was found that the surfactants which has the highest molecular (8φ C₁₅ ABS) gave (n_min) equal 8, so it can be used in the enhanced oil recovery(EOR) without additives (the suitable (n_min) for EOR between 7-9). Otherwise, the lowest molecular weight surfactant (7φ C₁₃ ABS) gave (n_min) equal 5 without addition of alcohols or electrolyte. This case needs some additives to adjust the (n_min) in the range of 7 to 9. By investigation the factors affecting (n_min), it was found that the side chain of alkyl benzene shifted the (n_min) to the highest values. The increasing of temperature decreased the (n_min) values. Also, it was found that the (n_min) increased to high value by adding the electrolytes and alcohols. The mixture between surfactants with and without side chain shifted the (n_min) to the highest value. Using these parameters, the alkane carbon number (n_min) can be used to select the suitable solvent during the preparation of emulsion to get the minimum interfacial tension at which the maximum emulsion stability should be obtained and also to select the surfactant for EOR.     

OCS表面活性剂在弱碱、无碱条件下的界面张力性能研究

研究了OCS表面活性剂中试产品在弱碱NaCO33及无碱条件下应用于不同油田原油的油-水界面张力特性。结果表明：对于大庆采油四厂原油，当表活剂浓度为0．1％-0．3％，Na2CO3浓度为0．6％-1．2％时，油-水界面张力可达到超低(-l0^-3mN／m数量级)；对于大庆采油二厂原油，当表面活性剂浓度为0．1％-0．3％，Na2CO3浓度为0．8％-1．4％时，油-水界面张力可达到超低；对于华北油田古-联原油，当表面活性剂浓度为0．2％，NaCO3浓度为0．6％-1．2％时，油-水界面张力可达到超低；对于胜利油田孤东采油厂原油，当表面活性剂浓度为0．2％，NaCO3浓度为0．8％-1．4％时，油-水界面张力可达到超低。在无碱条件下，对于大港油田枣园1256断块原油，当OCS表面活性剂浓度达到0．1％时，油-水界面张力即可达到超低；对于江苏油田原油，当OCS表面活性剂浓度在0．1％以上时，油-水界面张力均可以达到10^-2mN／m数量级。聚丙烯酰胺聚合物的加入对油-水超低界面张力的形成和稳定具有促进作用。     

新型三硅氧烷表面活性剂的合成与界面性能

低聚乙二醇单甲醚和环氧氯丙烷在相转移催化剂(P.T.C)存在下合成出低聚乙二醇甲醚缩水甘油醚, 然后与氨丙基三硅氧烷进行开环反应, 合成出了新型的三硅氧烷表面活性剂Me₃SiOSiMeROSiMe₃ [R＝(CH₂)₃N(CH₂CH(OH)CH₂- (OCH₂CH₂)_xOCH₃)₂, x＝1, 2]. 通过¹H NMR确证了这些目标产物的结构, 并且通过测定其水溶液的平衡表面张力研究了其表面活性. 在浓度约为10^－4 mol•L^－1时可以将水的表面张力降低至约21～22 mN•m^－1.     

Water-Diesel Microemulsions Stabilized by an Anionic Extended Surfactant and a Cationic Hydrotrope

Alcohol-free microemulsions were formulated using mixtures of extended surfactant (C_12-14-PO₁₄-EO₂SO₄Na), sodium dodecyl benzene sulfonic acid and cationic hydrotropes with equal amounts of water and diesel. The cationic hydrotropes had short hydrocarbon or propylene oxide chain. The formulation included sodium carbonate to convert naphthenic acids in diesel to soaps. The phase behavior at ambient temperature of oil-free mixtures as a function of NaCl concentration was investigated. Visual inspection as well as cross polarizers were used to detect anisotropy. The microemulsion fish phase diagram and solubilization ratios for diesel and brine in the middle phases were determined. The minimum surfactant concentration needed to initiate middle phase formation was 0.10 wt%.

Salinity scans revealed that optimal salinity can be adjusted according to the hydrophilic/lipophilic nature of the hydrotrope used. Interfacial tension measurements using a spinning drop tensiometer showed a minimum value of 0.0015 mN/m between middle phase microemulsion and excess brine and a value of 0.032 mN/m between diesel and brine.     

Effect of Aqueous Phase pH on the Dynamic Interfacial Tension of Acidic Crude Oils and Myristic Acid in Dodecane

The time dependence of the interfacial tension between water–acidic crude oil and water–synthetic oil was investigated for aqueous phase pHs ranging from 2 to 9 using the du Noüy ring method at 20°C. Myristic acid in dodecane was selected as a model (synthetic oil) for acidic crude oil containing indigenous surfactants, and the similarities and differences between the dynamic interfacial tension behaviours of the natural and synthetic crude oil systems were compared. The initial interfacial tension and the relaxation of the interfacial tension are sensitive to the aqueous phase pH for both systems. The adsorption kinetics of the indigenous surfactants and myristic acid could be well fitted with the monoexponential model, and the time constants obtained in this manner indicates that reorganization of the indigenous surfactants and myristic acid at the w/o interface are pH dependent. The experimental results also indicate that indigenous surfactants in acidic crude oil and myristic acid in dodecane have similar film formation behaviours at the w/o interface for the range of pHs investigated.     

Interfacial tension of alkylglucosides in different APG/oil/water systems

The interfacial performance of pure alkylglucosides (C₈G₁, C₁₀G₁ and C₁₂G₁) and of technical grade alkylpolyglucoside (APG) surfactants was investigated in three different water/oil systems (decane, isopropylmyristate and 2-octyldodecanol). From the dependence of the interfacial tension on the surfactant concentration below the CMC the cross-sectional area of the molecules at the decane/water interface was estimated. The plateau values of the interfacial tension at the CMC _c are independent of temperature and almost independent of added electrolyte in the decane/water system. The ability of the surfactants to lower the oil/water interfacial tension is most pronounced for the nonpolar oil. The partition coefficient of the surfactant between oil and water phase (k _c) was estimated from the CMC and the observed break point of the interfacial tension after equilibration of the two phases. In decane/water,k _c is nearly zero for all surfactants studied. For the polar oils,k _c increases with the chain length of the surfactant up tok _c10 for C₁₂G₁ in octyldodecanol/water. The values of _c in the different oil/water systems appear to be correlated withk _c and exhibit a minimum neark _c=1.     

Study on the Interfacial Tensions Between Oils and Alkylbenzene Sulfonate Gemini Surfactant Solutions

Interfacial tensions (IFT) of five alkylbenzene sulfonate Gemini surfactants Ia, Ib, Ic, Id, and Ie at different oils/water systems were measured by a spinning drop interfacial tensiometer. And critical micelle concentration (CMC), the interfacial tension at CMC (γ_CMC), maximum interfacial excess concentration (Γ _max) and the surface area per molecule (A_min) were calculated. The results indicated that the CMC values determined with interfacial tension method were lower than those determined with surface tension method. And γ_CMC for Ie is larger than that for Ia, Ib, Ic, and Id. In addition, the effects of temperature and hydrophobic chains on dynamic IFT were also studied. With the increment of temperature, dynamic IFT is easier to reach a stable value. However, with the increment of hydrophobic chains, dynamic IFT is more difficult to reach a stable value. Each Gemini surfactant produces a minimum IFT when measured against a different n-alkane.     

An Artificial Electrode/Electrolyte Interface for CO2 Electroreduction by Cation Surfactant Self-Assembly

In this work, an artificial electrode/electrolyte (E/E) interface, made by coating the electrode surface with a quaternary ammonium cation (R₄N⁺) surfactant, was successfully developed, leading to a change in the CO₂ reduction reaction (CO₂RR) pathway. This artificial E/E interface, with high CO₂ permeability, promotes CO₂ transportation and hydrogenation, as well as suppresses the hydrogen evolution reaction (HER). Linear and branched surfactants facilitated formic acid and CO production, respectively. Molecular dynamics simulations show that the artificial interface provided a facile CO₂ diffusion pathway. Moreover, density-functional theory (DFT) calculations revealed the stabilization of the key intermediate, OCHO*, through interactions with R₄N⁺. This strategy might also be applicable to other electrocatalytic reactions where gas consumption is involved.     

Ultra-Low Interfacial Tension Between Heavy Oil and Betaine-Type Amphoteric Surfactants

Betaine surfactants with lipophilic groups of different lengths were synthesized in this research and the dynamic interfacial tension (IFT) between solutions of these surfactants and three kinds of crude oil from Shengli Oilfield are measured. The results indicated that, for Gudao and Gudong heavy oil, cetyl dimethyl hydroxyl sulfobetaine (SBET-16) was the most efficient in lowering the IFT in the case of no alkalis, while for Shengtuo heavy oil, cetyl dimethyl carboxymethyl betaine (CBET-16) was best. SBET-16 with the concentration of 0.003–0.1% and 0.005–0.1% can reduce the oil/water IFT to ultra-low for Gudao and Gudong oil respectively, CBET-16 with the concentration of 0.005–0.1% can lower the oil/water IFT to ultra-low for Shengtuo oil. These results showed that for different oils, an oil displacement agent with high capacity to lower the oil/water interfacial tension may be obtained only by changing the molecular structure of betaine surfactant. This study can be used to guide the design of surfactants for alkaline-free combination flooding.