Synergistic anionic/zwitterionic mixed surfactant system with high emulsification efficiency for enhanced oil recovery in low permeability reservoirs

Emulsification is one of the important mechanisms of surfactant flooding. To improve oil recovery for low permeability reservoirs, a highly efficient emulsification oil flooding system consisting of anionic surfactant sodium alkyl glucosyl hydroxypropyl sulfonate(APGSHS) and zwitterionic surfactant octadecyl betaine(BS-18) is proposed. The performance of APGSHS/BS-18 mixed surfactant system was evaluated in terms of interfacial tension, emulsification capability, emulsion size and distribution, wettability alteration, temperature-resistance and salt-resistance. The emulsification speed was used to evaluate the emulsification ability of surfactant systems, and the results show that mixed surfactant systems can completely emulsify the crude oil into emulsions droplets even under low energy conditions. Meanwhile,the system exhibits good temperature and salt resistance. Finally, the best oil recovery of 25.45% is achieved for low permeability core by the mixed surfactant system with a total concentration of 0.3 wt%while the molar ratio of APGSHS:BS-18 is 4:6. The current study indicates that the anionic/zwitterionic mixed surfactant system can improve the oil flooding efficiency and is potential candidate for application in low permeability reservoirs.

Partitioning of biomaterials in aqueous two-phase systems of mixed cationic-anionic surfactants

In a previous paper, we have showed that, when aqueous solutions of cationicand anionic surfactants at certain concentrations were mixed, the solution separatedspontaneously into two immiscible phases (aqueous two-phases), one phase was rich,and the other was poor in the mixed surfactants. A clear interfacial boundary existsbetween two phases.

Separation of Biphenyl Nitrile Compounds by Microemulsion Electrokinetic Chromatography with Mixed Surfactants

A mixture of nine biphenyl nitrile compounds with high hydrophobicity and similar structures was successfully separated by microemulsion electrokinetic chromatography (MEEKC) within 30 min. The buffer system contained 100 mmol/L sodium dodecyl sulfate (SDS), 80 mmol/L sodium cholate (SC), 0.81% heptane, 7.5% n-butanol, 10% acetonitrile and 10 mmol/L borate. The addition of SC, organic modifiers, sample preparation and temperature all showed remarkable effect on the separation. Meanwhile, the MEEKC method was briefly compared with micellar electrokinetic chromatography (MEKC) method.

Vesicle Formation from Equimolar Cationic-anionic Surfactant Mixture in Non-aqueous Media

Unilamellar vesicles from the mixtures of 1:1 sodium 10-undecenoate and trimethyl[2-(10-undecenoyloxy)ethyl]ammonium iodide in the mixed solvents of ethanol and heptane can be formed spontaneously or by sonication. They can exist in the variation of concentrations and volume ratios of ethanol to heptane, which indicates to some extent the high capability of vesicle formation in such mixed systems.

Sensitizing Effect of Mixed Surfactants on the Colouration of Scandium(Ⅲ)with Phenylfluorone or Its Derivatives

In the presence of mixed micelle of a cationic and a nonionic surfactants,the reaction of scandium(Ⅲ) with phenylfluorone or its derivatives results in a very sensitive colouration:furthermore this chromophoric system tolerates the existence of a considerable amount of masking agents,so that many interfering ions can be masked and its selectivity would be further improved.After studying the optimum conditions and main charac- ters of some similar systems,the system of Sc(Ⅲ)—Orthonitrophenyuorone—Cetyltrimethylammonium Bromide(CTMAB)—Triton X-200 is chosen for the spectrophotometric determination of microamount of scandium.The proposed method shows not only high sensitivity(with a molar absorptivity of 2.12×1~sL mol^(-1)·cm^(-1))and selectivity,but also high tolerance of chromophoric conditions.Beer's law is obeyed over a range of 0～6.0 μg Sc/25ml.If the dual-wavelength method is applied,a much higher molar absorptivity o|' 3.04×10~5L·mol^(-1)·cm^(-1)than those of other systems ever reported in the literatures can be attained:more- over.its linear range is extended to 0～8.0 μg Sc/25ml and its reproducibility is also improved.

Temperature-resistant and salt-tolerant mixed surfactant system for EOR in the Tahe Oilfield

A new temperature-resistant and salt-tolerant mixed surfactant system(referred to as the SS system)for enhancing oil recovery at the Tahe Oilfield(Xinjiang,China)was evaluated.Based on the analysis of the crude oil,the formation water and rock components in the Tahe Oilfield,the long-term thermal stability,salt tolerance and the ability to change the wettability,interfacial activity and oil washing efficiency of the mixed surfactant system were studied.The system contains the anionic surfactant SDB and another cationic surfactant SDY.When the total mass concentration of the SS solution is 0.15 wt%,m(SDB)/m(SDY)ratio is 1 to 1,and excellent efficiencies are achieved for oil washing for five kinds of Tahe Oilfield crude oils(more than 60%).In addition,after adding cationic surfactant,the adsorption capacity of the surfactant is further reduced,reaching 0.261 mg/g.The oil displacement experiments indicate that under a temperature of 150°C and a salinity of 24.6×104 mg/L,the SS system enhances the oil recovery by over 10%after water flooding.The SS anionic–cationic surfactant system is first presented in the open literature that can be successfully applied to obtain predictions of Tahe Oilfield carbonate reservoirs with a high temperature and high salinity.

Study on aqueous two-phase systems of the mixture SDS/CTAB surfactants

The phenomenon of two dilute aqueous phases composed of sodium dodecylsulfate(SDS) and cetyl trimethyl ammonium bromide(CTAB) was investigated under various conditions such as concentrations and molar ratios of the two surfactants, the addition of sodium chloride and temperature. Vesicles formation was found in the both phases by TEM image.

An Experimental Study on Alkaline/Surfactant/Polymer Flooding Systems Using Natural Mixed Carboxylate

Orthogonal-test-design method has been used to determine the optimal formula by phase behavior and interfacial tension studies, respectively. The effect of each component of two alkaline/surfactant/polymer flooding systems on interfacial tension is discussed, in which a low-price natural mixed carboxylate (SDC) is used as the major surfactant. The results indicate that the optimal composition is SDC (0.5%), alkaline NaHCO3/Na2CO3 with mass ratio of 1 (1.0%), and hydrolyzed polyacrylamide(0.1%). In the coreflood experiment, their oil recovery is increased by about 25.2% and 26.8% original oil in place, respectively.

Interaction of nonionic surfactant AEO_9 with ionic surfactants

The interaction in two mixtures of a nonionic surfactant AEO9 (C12H25O(CH2CH2O)9H) and different ionic surfactants was investigated. The two mixtures were AEO9/sodium dodecyl sulfate (SDS) and AEO9/cetyltrimethylammonium bromide (CTAB) at molar fraction of AEO9, A EO9 α =0.5. The surface properties of the surfactants, critical micelle concentration (CMC), effectiveness of surface tension reduction (γCMC), maximum surface excess concentration (Γmax) and minimum area per molecule at the air/solution interface (Amin) were determined for both individual surfactants and their mixtures. The significant deviations from ideal behavior (attractive interactions) of the nonionic/ionic surfactant mixtures were determined. Mixtures of both AEO9/SDS and AEO9/CTAB exhibited synergism in surface tension reduction efficiency and mixed micelle formation, but neither exhibited synergism in surface tension reduction effectiveness.

Mixed Monolayers of Tween-80 and Oleic Acid at Air/Water Interface

Polyoxyethylene sorbitan monooleate(Tween-80) and oleic acid(OA) with different molar ratios were mixed and spread at air/water interface on subphases with varied pH values by using a Langmuir trough to investigate the laws governing the performance of the two components.The surface excess free energy(△G_M^(exc)) of mixed monolayers with various mixed molar ratios at different pH values under the surface pressure of 10 mN/m was analyzed,for the compatibility evaluation of mixtures in the monolayer.The results indicated that Tween-80 and OA could be miscible in thermodynamics under almost all the conditions in the experiments,except when the molar ratios of OA were more than 0.5 on the alkaline subphase at pH 9.5.The better thermodynamic compatibility between OA and Tween-80 occurred as the surface pressure was 10 mN/m,when the molar ratios of OA were 0.7 and 0.1 respectively in our experiments.

Experimental Study of Surface and Solution Properties of Gemini -conventional Surfactant Mixtures on Solubilization of Polycyclic Aromatic Hydrocarbon

Experimental data are presented on the enhanced solubilities of fluorene (FLR) resulting from solubilization in aqueous solutions of two conventional surfactants: cationic cetyltrimethylammonium bromide (CTAB) , anionic sodium dodecyl sulfate (SDS), nonioinic polyethylene glycol dodecyl ether (Brij35) and a cationic gemini bis (hexadecyldimethylammonium) pentane dibromide (G5). The critical micellar concentration of surfactants was determined by surface tension measurements and aqueous solubilities of fluorene compound in surfactant solutions were measured spectrophotometrically. Solubilization of PAH compound commenced at the surfactant critical micelle concentration and was proportional to the concentration of surfactant in micelle. The results of the mixed systems were analyzed with the help of regular solution theory, in which the deviation of CMCexp values for mixed surfactant systems from CMCideal was measured by evaluating the interaction parameter, βm. Negative values of βm were observed in all equimolar binary systems which show synergism in the mixed micelle. Attraction force between two oppositely charged head groups lead the strongest synergism effect between cationic gemini and anionic conventional surfactant. In addition to molar solubilization ratio (MSR) solubilization efficiency is also quantified in terms of micelle-water partition coefficient (Km).

Interaction of antipsychotic drug with novel surfactants: Micellization and binding studies

The interaction of cationic gemini surfactants(alkanediyl-α,ω-bis(alkyl dimethylammonium bromide)) with an antipsychotic drug(chlorpromazine hydrochloride(CPZ)) has been investigated. Various micellar and interfacial parameters have been deliberated by surface tension measurement to report the nature of interactions between drug and novel surfactant mixtures. The behavior of mixed systems, their compositions and activities of components have been analyzed in the light of Rubingh's theory. The results indicate synergism in the binary mixtures.The binding study between CPZ and surfactants has been done by spectroscopic techniques such as UV–visible and fluorescence. The results are discussed in the light of the use of gemini surfactants as promising drug delivery agents for phenothiazine drugs, and hence, improve their bioavailability.

添加剂改性固态胺吸附剂用于碳捕集的研究进展

固态胺是固体吸附CO_(2)捕集技术路线中的研究热点,是烟气碳捕集和直接空气碳捕集技术中最有应用前景的吸附剂材料,近年来受到广泛关注。目前,固态胺吸附剂的吸脱附性能以及热化学稳定性仍有较大提升空间。本文综述了近年来表面活性剂、胺类和无机物类,以及环氧化物、螯合剂和含硫化合物等添加剂对固态胺吸附剂吸附能力增强和热化学稳定性提升的研究成果。在此基础上,进一步介绍了不同种类添加剂对固态胺吸附剂的改性机理,总结了在不同碳捕集工况下添加剂对固态胺吸附剂的改性特点。尽管现有研究已经取得了一些进展,但添加剂改性固态胺吸附剂仍然面临挑战,尤其是目前尚未能充分实现增强固态胺吸附剂的吸附能力和热化学稳定性的双重目标。此外,鉴于不同碳捕集工况下气体成分显著不同,未来研究需要更加明晰不同碳捕集工况下添加剂对固态胺吸附剂吸脱附热力学、动力学以及热化学稳定性的影响,并根据具体碳捕集工况有针对性地设计添加剂改性方案。

表面活性泡沫沥青发泡工艺及流变特性研究

温拌沥青技术可降低沥青混合料生产和施工温度,在节能减碳方面极具应用潜力。泡沫温拌沥青技术成本较低,虽存在改性沥青发泡效果不理想、温拌效果不显著等问题,但具有潜在的推广应用前景。表面活性剂兼具“沥青润滑剂”和“泡沫稳定剂”的作用效能,为改善泡沫温拌沥青发泡特性和温拌效果提供了可能。基于此,本研究采用不同质量分数的表面活性剂水溶液,在不同发泡温度下制备了表面活性泡沫沥青(SAFB6,SAFB8,SAFB10),利用发泡试验、动态剪切流变试验以及弯曲梁流变试验测试了沥青的发泡特性、高温性能、抗疲劳性能和低温性能,并借助傅里叶红外光谱试验分析了作用机理,揭示了表面活性剂与发泡过程对泡沫温拌沥青性能的协同提升作用。试验结果表明:表面活性剂对SBS改性沥青的发泡特性有明显的协同作用,特别是半衰期,最大可达69 s;SAFB沥青最佳发泡条件为发泡温度170℃,表面活性剂含量8%;SAFB沥青制备过程中没有发生复杂的化学反应,但是发泡过程导致SBS改性沥青发生了一定程度的氧化作用;表面活性剂和发泡工艺的协同效应提高了SBS改性沥青的高温性能和抗疲劳性能,而低温抗裂性能与SBS改性沥青相当。总体而言,表面活性剂与发泡技术相结合是可行的,提高了SBS改性沥青的发泡效果和路用性能。

Synthesis of nanoiron by microemulsion with Span/Tween as mixed surfactants for reduction of nitrate in water

Denitrification of nitrate in groundwater using iron nanoparticles has received increasing interest in recent years.In order to fabricate iron nanoparticles with homoge-neously spherical shape and narrow size distribution,a simple and“green”method was developed to synthesize iron nano-particles.The conventional microemulsion methods were modified by applying Span 80 and Tween 60 as mixed sur-factants.The maximum content of water in the Water-in-oil(W/O)microemulsion and its appropriate forming conditions were found,and then the microemulsion system consisting of saturated Fe^(2+)solution was used to synthesizeα-Fe ultrafine particles by redox reaction.The nanoparticles were characterized by using powder X-ray diffraction(XRD)and transmission electron microscopy(TEM).The results show that the average diameter of the particle is about 80-90 nm.The chemical activity of the obtained iron nanoparticles was studied by the denitrification experiment of nitrate.The results show that under the experimental conditions,iron removed most of the 80 mg/L nitrate within 30 min.The mass balance of nitrate reduction with nanoscale Fe indicates that endproducts are mainly ammonia.Two possible reaction pathways for nitrate reduction by nanoscale iron particles have been proposed in this work.

Removal of Ni（ll） ions from wastewater by micellar enhanced ultrafiltration using mixed surfactants

Ni（II） ions were removed from aqueous waste using micellar enhanced ultrafiltration （MEUF） with a mixture of surfactants. The surfactant mixture was the nonionic surfactant Tween 80 （TW80） mixed with the anionic surfactant sodium dodecyl sulfate （SDS） in different molar ratios ranging from 0.1-1.5. The opera- tional variables of the MEUF process such as pH, applied pressure, surfactant to metal ion ratio and nonionic to ionic surfactant molar ratio （α） were evaluated. Rejection of Ni and TW80 was 99% and 98% respectively whereas that for SDS was 65%. The flux and all resistances （fouling resistance, resistance due to concentration polarization） were measured and calculated for entire range of α respectively. A calculated flux was found to be declined with time, which was mainly attributed to concentration polarization rather than resistance from membrane fouling.

Injection of biosurfactant and chemical surfactant following hot water injection to enhance heavy oil recovery

This study investigates the potential of enhancing oil recovery from a Middle East heavy oil field via hot water injection followed by injection of a chemical surfactant and/or a biosurfactant produced by a Bacillus subtilis strain which was isolated from oil-contaminated soil.The results reveal that the biosurfactant and the chemical surfactant reduced the residual oil saturation after a hot water flood.Moreover,it was found that the performance of the biosurfactant increased by mixing it with the chemical surfactant.It is expected that the structure of the biosurfactant used in this study was changed when mixed with the chemical surfactant as a probable synergetic effect of biosurfactant-chemical surfactants was observed on enhancing oil recovery,when used as a mixture,rather than alone.This work proved that it is more feasible to inject the biosurfactant as a blend with the chemical surfactant,at the tertiary recovery stage.This might be attributed to the fact that in the secondary mode,improvement of the macroscopic sweep efficiency is important,whereas in the tertiary recovery mode,the microscopic sweep efficiency matters mainly and it is improved by the biosurfactantchemical surfactant mixture.Also as evidenced by this study,the biosurfactant worked better than the chemical surfactant in reducing the residual heavy oil saturation after a hot water flood.

Synthesis of Iron Nanoparticles by Thermal Decomposition of Diironnonacarbonyl in Ionic Liquid and Their Potential Use as Nanotracers for Mixer Studies in Liquids Feeds

Iron nanoparticles with dynamic light scattering median diameter around 10 nm have been prepared by thermal decomposition under a nitrogen atmosphere from diironnonacarbonyl (DINC) dissolved in n-butyl-3-methylimidazolium tetrafluoroborate (BMIMBF). The effect of temperature changes in the range of 170°C - 200°C and changes in concentration of DINC in BMIMBF in the range of 0.1% - 0.9% on the properties of obtained iron nanoparticles has been investigated. The stable dispersion of iron nanoparticle in ethanol has been prepared after separation of nanoparticles from ionic liquid by centrifugation following by their re-dispersion in ethanol. The possibility of quantitative analysis of iron content in ethanol dispersion by deposition of ferromagnetic nanoparticles on the surface of plastic-protected neodymium magnet, dissolution of iron in hydrochloric acid and addition of ammonium thiocyanate solution following by spectrophotometric determination of iron cations at wavelength of 490 nm has been investigated. The feasibility of using the same approach in case of addition of ethanol dispersion of iron nanoparticles to the liquid animal feeds for evaluation of efficiency of their mixing has been discussed.

耐温抗高钙镁油藏驱油表面活性剂复配体系的研究

针对现有复合驱技术对地层原油黏度高于120 mPa·s、地层水钙镁离子含量超过1000 mg/L的油藏普遍存在驱油效果不理想的问题,优选了非离子表面活性剂月桂酸二乙醇酰胺和阴离子表面活性剂十二烷基磺酸钠进行复配,考察了复配表面活性剂的油水界面张力、接触角、对原油的乳化力、对油砂的洗油能力等性能,实验结果表明,当m(月桂酸二乙醇酰胺)∶m(十二烷基磺酸钠)=5.3时,复配表面活性剂在高温、高矿化度、高钙镁含量条件下,均具有较低的油水界面张力,同时具有较好的润湿性能和对油砂较高的洗油能力。

二元混合表面活性剂对纳米流体热物性影响

采用两步法制备了添加二元混合表面活性剂的氧化锌纳米流体,纳米颗粒的体积浓度为0.398%~2.292%。XRD、TEM对氧化锌纳米粒子进行表征,吸光度法和沉降法分析了纳米流体稳定性,之后研究15~55℃时,制备流体的导热与黏度,并与添加单一表面活性剂的纳米流体进行对比。实验结果显示,添加SDS/CTAB纳米流体稳定性更优。纳米流体导热系数随温度及纳米粒子体积浓度的增加而增大,55℃,2.292%的纳米流体热导率增强最大,提高了38%,且热导率增强作用明显优于单一表面活性剂的添加。纳米流体黏度随温度及纳米粒子体积浓度的增加而逐渐降低,在55℃,2.292%时拥有最小黏度0.645 mPa·s。与单一表面活性剂相比,SDS/CTAB的添加能有效降低纳米流体黏度,对减小纳米流体黏度有积极作用。