Diesel Oil Removal by Froth Flotation Under Low Interfacial Tension Conditions II: Continuous Mode of Operation

Abstract

The objective of this study was to investigate the relationship between interfacial tension (IFT) and foam characteristics and the efficiency of diesel oil removal from water in a continuous froth flotation column. The effects of operational parameters, including surfactant concentration, salinity, oil-to-water ratio, foam height, air flow rate, and hydraulic retention time (HRT) on the oil removal were investigated in the continuous mode of a froth flotation operation and compared to batch operation results. Unlike the batch system, for the continuous system used in the present study, having only branched alcohol propoxylate sulfate sodium salt surfactant (C_14–15(PO)₅SO₄Na) and NaCl present in the solution yielded such poor foam characteristics that a stable froth which overflowed the flotation column could not be produced, so the addition of sodium dodecyl sulfate (SDS) as a froth promoter was used to improve the foam stability. Unlike the batch froth flotation system with only C_14–15(PO)₅SO₄Na, the continuous froth flotation with the mixture of C_14–15(PO)₅SO₄Na and SDS, it was not possible to find a SDS and a NaCl concentration at which both ultralow IFT and good foaming were both achieved. Foam formation, stability, and production rate were found to be crucial parameters to the froth flotation efficiency. The continuous froth flotation system offers a high diesel oil removal of 96% in the single stage unit. Demonstration of efficient operation in the continuous mode in this work is important to the practical application of froth flotation in large scale processing.     

Microemulsion formation and detergency with oily soils: III. Performance and mechanisms

The objective of this study was to investigate the correlation between oily soil removal efficiency and low oil-water interfacial tension (IFT) generated by microemulsion formation. A mixture of sodium dioctyl sulfosuccinate, alkyl diphenyl oxide disulfonate, and sorbitan monooleate was selected as a detergent formulation to evaluate detergency performance for two highly hydrophobic oils: hexadecane and motor oil. The maximum detergency corresponds to formation of a Winsor Type III microemulsion as well as to the supersolubilization region, which is a Winsor Type I microemulsion close to the Winsor Type III region. In addition, the oil removal in the rinse step is almost as high as that in the wash step for both regions. We propose the following mechanism to explain these results: During the wash step, the contact angle of the oil on the fabric surface is progressively increased, resulting in the detachment of the oil droplets. However, owing to the very low IFT, the spreading effect is dominant, thereby causing incomplete oil removal. During the subsequent rinse step, the IFT increases, passing through a composition at which the rollup mechanism causes additional oil removal. These results demonstrate that microemulsion formation and the resulting IFT reduction are important mechanisms in oily soil detergency.     

Enhanced triolein removal using microemulsions formulated with mixed surfactants

In previous work, a microemulsion-based formulation approach yielded excellent laundry detergency with hydrophobic oily soils hexadecane and motor oil. In this work, the same approach is used in detergency of triolein, which is a model triglyceride, some of the most difficult oils to be removed from fabric. The linker concept was applied in formulation of the microemulsion system. Three different surfactants were used: (i) dihexyl sulfosuccinate, an ionic surfactant with a moderate hydrophile-lipophile balance (HLB); (ii) secondary alcohol ethoxylate, a lipophilic nonionic surfactant with a very low HLB; and (iii) alkyl diphenyl oxide disulfonate (ADPODS), a hydrophilic anionic surfactant with a very high HLB. The phase behavior and interfacial tension (IFT) of the surfactant systems were determined with different concentrations of ADPODS. The results indicate that as the HLB of the system increases, a higher salinity is required to shift the phase transition from Winsor Type I to Type III to Type II. The three formulations at different salinities were used in detergency experiments to remove triolein from polyester/cotton sample fabric. The results showed that there were two peaks of maximum detergency in the range of salinity from 0.1% to 10% NaCl. The higher the hydrophilicity of the system, the higher the salinity required for maximum detergency. The results of the dynamic IFT and the detergency performance from two rinsing methods lead to the hypothesis that one of these maxima in detergency results from a spreading or wetting effect. The other maximum in detergency is believed to be related to ultralow IFT associated with oil/water middle-phase microemulsion formation. Triolein removal exceeding 80% was attained, validating the microemulsion approach to detergency.     

Remediation of diesel oil contaminated sand by micro-emulsion

Micro-emulsion has unique advantages in repairing diesel oil contaminated sand due to its low interfacial tension and strong solubility. By Winsor phase diagram, it was found that with the increase of salinity, the phase of microemulsion transformed from Winsor Ⅰ to Winsor Ⅲ to Winsor Ⅱ. Under cryogenic electron microscope, it was observed that Winsor Ⅰ was O/W type, Winsor Ⅱ was W/O type, and Winsor Ⅲ type was bi-continuous type. The effect of inorganic salts, alcohol and temperature on the oil removal rate of diesel oil contaminated sand was investigated by static recovery of micro-emulsion precursor. The results showed that for the anionic microemulsion system, with the increase of salinity and alcohols, the oil yield of the upper phase increased first and then decreased, and the two components had a certain compensation effect. For non-ionic micro-emulsion system, with the increase of temperature, the oil yield in the upper phase rose first and then decreased. At the same time, the influence of leaching conditions on oil removal rate was investigated by one-dimensional sand column leaching experiment. It was found that for diesel oil contaminated sand with 15% oil content, when the formulation was 2.00 wt% SDBS, 4.05 wt% n-butanol and 0.40 wt% sodium chloride, the optimum leaching conditions were leaching rate of 4 ml·min~(-1) and leaching amount of 400 ml. Under such conditions, the oil removal rate was up to 82.84%, that is, the oil content of the sand was reduced to 2.57%. Moreover, the micro-emulsion has good cyclicity, and it can still achieve high oil yield after six cycles.     

Microemulsion formation and detergency with oily soils: II. Detergency formulation and performance

In part I of this series (J. Surfact. Deterg. 6, 191–203, 2003), the mixed surfactant system of sodium dioctyl sulfosuccinate (AOT), alkyl diphenyl oxide disulfonate (ADPODS) and sorbitan monooleate (Span 80) was shown to form Winsor type I and type III microemulsions with hexadecane and motor oil. In addition, high solubilization and low interfacial tension were obtained between the oils and surfactant solutions both in the supersolubilization region (Winsor type I system close to type III system) and at optimal conditions in a type III system. In the present study, this mixed surfactant system was applied to remove oily soil from fabric (a polyester/cotton blend), and detergency results were correlated to phase behavior. Dynamic interfacial tensions were also measured between the oils and washing solutions. In the supersolubilization and in the middle-phase regions (type III), much better detergency performance was found for both hexadecane and motor oil removal than that with a commercial liquid detergent product. In addition, the detergency performance of our system at low temperature (25°C) was close to that obtained at high temperature (55°C), consistent with the temperature robustness of the microemulsion phase behavior of this system.     

Preparation and Performance Evaluation of Fatty Amine Polyoxyethylene Ether Diethyl Disulfonate for Enhanced Oil Recovery in High‐Temperature and High‐Salinity Reservoirs

To enhance oil recovery in high‐temperature and high‐salinity reservoirs, a novel fatty amine polyoxyethylene ether diethyl disulfonate (FPDD) surfactant with excellent interfacial properties was synthesized. The interfacial tension (IFT) and contact angle at high temperature and high salinity were systematically investigated using an interface tension meter and a contact angle meter. According to the experimental results, the IFT between crude oil and high‐salinity brine water could reach an ultra‐low value of 10^?3 mN m^?1 without the aid of extra alkali at 90°C after aging. The FPDD surfactant has strong wettability alternation ability that shifts wettability from oil‐wet to water‐wet. The FPDD surfactant with a high concentration also has good emulsion ability under high‐temperature and high‐salinity conditions. Through this research work, we expect to fill the lack of surfactants for high‐temperature and high‐salinity reservoirs and broaden its great potential application area in enhanced oil recovery.     

Alcohol-free diphenyl oxide disulfonate middle-phase microemulsion systems

Diphenyl oxide disulfonate (DPDS) surfactants were successfully used to formulate Winsor Type III middlephase microemulsion systems with tetrachloroethylene (PCE) and decane. To our knowledge this is the first time that monochain DPDS surfactant phenyloxide monohexadecyl disulfonate surfactant (C16MADS) and commercially available DOWFAX 8390 were found to form middle-phase microemulsion systems with oils. Hydrophobic dioctyl sodium sulfosuccinate (Aerosol OT) was also used as a cosurfactant to lower the systems' hydropholic-liphophilic balance. Two organic acids (hydrophobic octanoic acid and hydrophilic l-tartaric acid) were used in place of the alcohol to formulate middle-phase microemulsion. The middle-phase microemulsion systems dramatically increased organic solubility when compared to micellar DPDS surfactant systems. Winsor Type I systems near the Type I–III boundary produced “super” solubilization for hydrophobic oils. Findings from this study enable us to improve DPDS solubilization enhancement of hydrophobic compounds.     

Phase Behavior of Non-Ionic Surfactant-Medium Chain Triglyceride-Water Microemulsion Systems

Microemulsion systems have garnered tremendous interest in the pharmaceutical sector for a variety of drug delivery applications. Non-ionic surfactants are often the preferred surfactant class given their uncharged nature, enhanced oral safety profile, and generally regarded as safe status as compared to other surfactant classes (Myers, Surfactant science and technology, 2005, p. 29), (Malmsten, Handbook of microemulsion science and technology, 1999, p. 755), (Grove & Mullertz, Chapter 5-liquid self-microemulsifying drug delivery systems, 2007), (Liu et al., Water-insoluble drug formulation, 2008), (Hauss, Advanced Drug Delivery Reviews, 2007, 59, pp. 667–676), (Balazs, Solubility, delivery and ADME problems of drugs and drug-candidates, 2011, p. 68). In this work, the phase behavior and microemulsion formation potential of four commonly used non-ionic surfactants, PEG-40 hydrogenated castor oil, Poloxamer 188, Polysorbate 80, and d -α-tocopherol polyethylene glycol succinate were studied via ternary phase diagram (TPD) mapping using a medium chain triglyceride, Miglyol 812. Results indicated notable differences in phase behavior despite similarities in hydrophilic–lipophilic balance value (13–15). All surfactants produced Winsor Type I, oil-in-water microemulsions at water concentrations above 40% wt/wt. Winsor Type II water-in-oil microemulsions were difficult to obtain even at high oil concentrations of ≥70% wt/wt. Winsor III microemulsions, though rare, were generally obtained in the middle regions of the TPD between 10% and 30% wt/wt water while Winsor IV microemulsions dominated at high surfactant concentrations of ≥45% wt/wt. Opaque emulsion areas were particularly notable in wax state surfactants. Polysorbate 80 and PEG-40 hydrogenated castor oil demonstrated a high degree of synergism as well as the largest oil-in-water (o/w) and water-in-oil (w/o) microemulsion formation potential rendering them suitable for a number of enteral and parenteral applications.     

Removal of motor oil by continuous multistage froth flotation: Effect of operational parameters

A continuous multistage froth flotation column was employed to remove motor oil from water at a low concentration (500 mg/L) using an extended surfactant – branched alcohol propoxylate sulphate sodium salt (C_14-15–8PO–SO₄–Na) – as a frother. The highest separation efficiency (97% motor oil removal with the enrichment ratio of 16 for motor oil) was obtained at a foam height of 60 cm, an air flow rate of 40 L/min, a feed flow rate of 60 mL/min, a surfactant concentration of 0.3% (w/v), and an NaCl concentration of 1.5% (w/v). The process performance increased with increasing tray number but beyond 4 trays, the system could only offer lower concentrations of motor oil and surfactant in the effluent.     

Microemulsion phase behavior of anionic-cationic surfactant mixtures: Effect of tail branching

This research evaluated middle-phase microemulsion formation by varying the mole ratio of anionic and cationic surfactants in mixtures with four different oils (trichloroethylene, n-hexane, limonene, and n-hexadecane). Mixtures of a double-tailed anionic surfactant (sodium dihexyl sulfosuccinate, SDHS) and an unbalanced-tail (i.e., doubletailed with tails of different length) cationic surfactant (benzethonium chloride, BCl) were able to form microemulsions without alcohol addition. The amount of NaCl required to form the middle-phase microemulsion decreased dramatically as an equimolar anionic-cationic surfactant mixture was approached. Although the mixture of anionic and cationic surfactants demonstrated a higher critical microemulsion concentration (cμc) compared to the anionic surfactant alone, the Winsor Type IV single-phase microemulsion started at lower surfactant concentrations for the anionic-cationic mixture than for the anionic surfactant alone. Under optimum middlephase microemulsion conditions, mixed anionic-cationic surfactant systems solubilized more oil than the anionic surfactant alone. Pretreatment detergency studies were conducted to test the capacity of these mixed surfactant systems to remove oil form fabrics. It was found that anionic-rich mixed surfactant formulations yielded the largest oil removal, followed by cationic-rich systems.     

无机盐对十六烷基三甲基溴化铵（CTAB）微乳液相行为的影响

微乳液通常由水、油、盐、表面活性剂及助剂组成,各组分对微乳液体系的相行为及增溶情况都有影响。本文利用Winsor相图和ε-β鱼状相图来研究无机盐种类、浓度对十六烷基三甲基溴化铵（CTAB）型微乳液相行为的影响。研究发现,随着无机盐浓度或醇量增加,微乳液都会发生从WinsorⅠ→WinsorⅢ→WinsorⅡ的相转变,但具有不同阳离子或阴离子的无机盐对微乳液体系相行为的影响不同。无机盐在微乳液体系中主要与表面活性剂的反离子发生作用,对阳离子表面活性剂配成的微乳液体系,无机盐阴离子的作用比较强,且价态越高,离子半径越大,对微乳液相态的影响越大。通过对不同无机盐条件下的界面组成及增溶参数分析可知：无机盐种类的改变对鱼头、鱼尾点表面活性剂含量及醇在界面层中的分布影响较小;无机盐中阴离子改变对微乳液增溶能力影响较大,阳离子的改变对微乳液增溶能力影响较小。     

Experimental Investigation into the Screening of New Surfactant Flowback Aids and Statistical Interpretation of Their Imbibing Capacity for Selected Core Substrates

Spontaneous imbibition is a pervasive part of many natural and industrial processes. As an inherent feature of fluid transport in porous media, it is a driver for oil recovery. Understanding spontaneous imbibition and leveraging surface science is fundamental for fluid recovery; specifically, the role of the surfactant in the imbibition processes and the potential to alter capillarity and wettability of reservoir rock. Surfactant success relies on the understanding of the factors governing the interfacial phenomena among crude oil, and formation properties under reservoir conditions. Developing a methodology coupling chemical performance with analytical techniques, and statistical interpretation of core/surfactant/oil interactions, can help establish workflows to advance new chemistries and enhance oil recovery. This article discusses a study of flowback aids formulated as microemulsions corresponding to the thermodynamically stable Winsor Type IV solutions. Neat formulated microemulsions, when dosed at field treatment concentrations, provide either oil-in-water droplet microemulsions or nanoemulsions. The solvency potential was measured, and the Kauri-butanol (Kb) value was determined. Parameters such as critical micelle concentration (CMC) and interfacial tension (IFT) were determined to characterize microemulsion solutions. These systems were tested using either in the column flow test with formation material sieved to match mineral grain size, or sandstone cores of various permeabilities. The results indicate that surfactant-based flow-enhancing aids are desirable for improved oil recovery when compared to the control fluid. The statistical analysis of core-fluid interaction includes an ANOVA followed by assumption evaluations and model interpretation, which demonstrates that the core permeability term, followed by the surfactant term, has the highest contribution whereas oil has no statistical significance to the model.     

磺基甜菜碱型两性离子表面活性剂的相行为研究

采用自制的4种磺基甜菜碱,运用多种方法对4种磺基甜菜碱/短链醇/正癸烷/NaCl/水形成的微乳液体系相行为进行了研究,并考察了温度、磺基甜菜碱的分子结构、短链醇浓度及其分子结构等对微乳液相行为的影响。实验表明:温度越高,中相微乳液形成的中相体积越大;SB9体系形成中相微乳液时,所需要的最小w(醇)为2%,最大醇宽为12%;SB12体系形成中相微乳液时所需要的最小w(醇)为4%,最大醇宽8%;随着磺基甜菜碱烷基碳数的增加,微乳区面积增大,增溶能力降低;最佳增容参数SP*和表面活性剂在油相和水相的平均溶解度SO.W均随短链醇碳链的增加而增加;平衡界面膜上的表面活性剂和醇在整个微乳液体系中所占的质量分数C S,C A,短链醇平衡界面膜所占的质量比AS,短链醇在油水相中的平均溶解度AO.W,均随短链醇碳链的增加而减小;w(醇)的增加使得微乳液体系发生由WinsorⅠ→WinsorⅢ→WinsorⅡ型的相态变化。     

Characterizations of surfactant synthesized from Jatropha oil and its application in enhanced oil recovery

Surfactants are frequently used in chemical enhanced oil recovery (EOR) as it reduces the interfacial tension (IFT) to an ultra‐low value and also alter the wettability of oil‐wet rock, which are important mechanisms for EOR. However, most of the commercial surfactants used in chemical EOR are very expensive. In view of that an attempt has been made to synthesis an anionic surfactant from non‐edible Jatropha oil for its application in EOR. Synthesized surfactant was characterized by FTIR, NMR, dynamic light scattering, thermogravimeter analyser, FESEM, and EDX analysis. Thermal degradability study of the surfactant shows no significant loss till the conventional reservoir temperature. The ability of the surfactant for its use in chemical EOR has been tested by measuring its physicochemical properties, viz., reduction of surface tension, IFT and wettability alteration. The surfactant solution shows a surface tension value of 31.6 mN/m at its critical micelle concentration (CMC). An ultra‐low IFT of 0.0917 mN/m is obtained at CMC of surfactant solution, which is further reduced to 0.00108 mN/m at optimum salinity. The synthesized surfactant alters the oil‐wet quartz surface to water‐wet which favors enhanced recovery of oil. Flooding experiments were conducted with surfactant slugs with different concentrations. Encouraging results with additional recovery more than 25% of original oil in place above the conventional water flooding have been observed. © 2017 American Institute of Chemical Engineers AIChE J, 63: 2731–2741, 2017     

Correlation between Detergency of Different Oily and Solid Non-Particulate Soils and Hydrophilic–Lipophilic Deviation

This research examined the correlation between the detergency of soils with varying equivalent alkane carbon numbers (EACN) and hydrophilic–lipophilic deviation (HLD) values. The detergency of oily soils with EACN ranging from 5.2 to 16.6 was evaluated using C₁₀-4PO-SO₄Na as a primary surfactant system and a 1:1 binary mixture of C₁₀-4PO-SO₄Na and AOT as a confirmatory surfactant system (with 65/35 polyester/cotton at 25°C). These surfactant systems were characterized using HLD concepts which showed that C₁₀-4PO-SO₄Na was more hydrophilic (had a higher negative Cc value) than that of the mixed surfactant system. Detergency of the selected soils was evaluated at different salinities corresponding to HLD ranging from negative to positive values. The results showed that detergency of all soils increased with increasing salinity (starting with an HLD = −3.0 (Winsor Type I microemulsion)), reached the maximum at widely different optimum salinity (S*) but at an identical HLD value of zero (optimum Type III), and then decreased with further increasing salt levels corresponding to positive HLD values (Type II). The preferred HLD range from −3.0 to 0.0 showed detergency levels exceeding 80% removal with interfacial tension values (IFT) below 1 mN m⁻¹ for all oily soils studied. Detergency of octadecane (EACN = 18, solid at 25°C) was further conducted and demonstrated that performing detergency at HLD = −3.0 to 0.0 likewise revealed superior soil removal (over 80%) versus systems with HLD values outside this range. Thus, this work highlighted the utility of using the HLD approach in designing surfactant formulations for detergency of soils with widely varying EACN.     

Microemulsion Formation and Detergency with Oily Soil: V. Effects of Water Hardness and Builder

In this study, the impact of water hardness and builder on the phase diagrams of motor oil microemulsions and the detergency of oil removal from a polyester/cotton blend was investigated. Water hardness and builder were found to have insignificant effects on the microemulsion phase diagram with motor oil. A mixed surfactant system of two parts C_14–15(PO)₃SO₄Na, and 98 parts C_12–14H_25–29O(EO)₅H of the total actives at 4% salinity was used to study the effect of water hardness and builders sodium tripolyphosphate (STPP) or ethylenediaminetetraacetic acid (EDTA) on detergency at 30 °C at a total active concentration of 0.3%. This formulation is in the Winsor Type III microemulsion regime. The microemulsion-based formulation resulted in better detergency than a leading commercial liquid laundry detergent at all concentrations up to 0.5% actives. The microemulsion-based formulation showed a plateau in detergency at >80% oil removal above 0.1% actives. The total oil removal decreased with increasing water hardness while the interfacial tension increased. When hard water was used in laundering, the total oil removal improved with increasing concentrations of STPP or EDTA up to stoichiometric levels, with STPP being slightly more effective than EDTA on a molar basis. Even high builder concentration could not improve hard water detergency to that of soft water. A significant fraction of oil removal occurred in the rinse steps vs. the wash step. Increasing water hardness reduced this fractional oil removal in the rinse steps, but it was still over half of total oil removal at 1,000 ppm water hardness.

Formation and Phase Behavior of Winsor Type III <Emphasis Type="Italic">Jatropha curcas</Emphasis>-Based Microemulsion Systems

The formation and phase behavior of Jatropha curcas-based microemulsion systems, which could potentially be used in enhanced oil recovery applications, has been investigated. Winsor type III microemulsions were obtained by adding n-octane to Winsor type I microemulsion systems prepared using various concentrations of alkyl polyglucoside (APG). To optimize the formulation of type III microemulsion systems, five different types of co-surfactants, i.e. normal butyl alcohol (NBA), isobutyl alcohol, isopropyl alcohol, fatty acid alcohol C8 (FAC8) and fatty acid alcohol C8/C10 (FAC8/C10) were used. The microemulsion phase behavior was determined along with particle size distributions by dynamic light scattering measurements. Results show that the optimum Winston type III system can be achieved by mixing 3 wt% of NBA, 1 wt% APG and 3 wt% NaCl. At the optimum formulation, the IFT reached a minimum value (0.016 mN/m) and formed very small emulsion droplets with a narrow particle size distribution.     

Enhancing solubilization in microemulsions—State of the art and current trends

Along a formulation scan, solubilization is maximal when a bicontinuous microemulsion is in equilibrium with both oil and water excess phases in a so-called Winsor III system. The logical way to enhance solubilization is to increase the interaction of the surfactant for both the oil and water phases, which can be easily attained by increasing the size of both the head and tail groups. However, this approach is limited by solubility constraints. Additional solubilization enhancement can be attained by introducing a molecule(s) that bridge the bulk phase and the adsorbed surfactant layer; this can be accomplished by using the so-called lipophilic and hydrophilic “linker effect” or by using block copolymer additives. In either case, the goal is to modify an extended zone in the oil and water domains close to their boundary. The intramolecular grafting of a linker group between the hydrophilic and lipophilic moieties in a surfactant results in a so-called “extended” surfactant structure, which produces enhanced solubilization, as does the surfactant/linker combination, but with the added benefit that the self-contained extended surfactant structure does not undergo selective partitioning. We conclude that an improvement in solubilization is directly related to the presence of a smooth, blurred, and expanded transition across the interfacial region from polar to apolar bulk phases.     

Removal of Emulsified Oil from Water by Coagulation and Foam Separation

Abstract

A new method of emulsified oil separation for oily wastewater incorporating simple operation and shortened treatment time is necessary for improved wastewater treatment in some manufacturing plants. In the present study, the removal of emulsified oil from water by coagulation and foam separation using poly aluminum chloride (PAC) and milk casein was examined. By adding casein before the foam separation process, the oil removal was dramatically improved. By using surfactant (LAS) as a frother, the dosage of casein was drastically reduced. Furthermore, for processing actual oily water, LAS was unnecessary because a sufficient amount of surfactants for foaming was included in the wastewater. For treatment of the actual oily wastewater collected from a steel manufacturing plant, the optimum condition for PAC and casein was 30 mg‐Al/L and 10 mg/L, respectively, and the oil concentration decreased from 170 mg/L to 2.2 mg/L. After examining several types of oily wastewater, 96–99% of oil removal efficiency was obtained by adjusting the dosages of PAC and casein. Coagulation and foam separation using casein has shown a high potential as an alternative method to dissolved air flotation (DAF) for processing emulsified oil water.     

Interfacial Tensions of Ethoxylated Fatty Acid Methyl Ester Solutions Against Crude Oil

The dynamic interfacial tension (IFT) of ethoxylated fatty acid methyl ester solutions against n‐alkanes, kerosene, and diluted heavy oil have been investigated by spinning drop interfacial tensiometry. The influences of ethylene oxide (EO) groups and alkyl chain length on IFT were investigated. The experiment results show that the water solubility decreases with an increase in alkyl chain length or a decrease in EO groups. The ability to lower the interfacial tension against hydrocarbons improves with both increasing alkyl chain length and EO group at the best hydrophilic‐lipophilic balance, which can be attributed to the enhancement of the interfacial hydrophobic interactions and the rearrangement of interfacial surfactant molecules. The mixed adsorption of surfactant molecules and surface‐active components may reduce IFT to a lower value. C₁₈=E₃ shows the best synergism with surface‐active components. However, the IFT values against pure crude oil are obviously higher than those against hydrocarbons, which may be caused by the nature of heavy oil.