IL-based Surfactants Research Articles

Efficiency of ionic liquid/polymer flooding combined with smart water injection on oil recovery through secondary and tertiary patterns using Iranian carbonate rock

The current investigation utilizes direct injection of modified smart water (SW) after oil flooding stage (secondary oil recovery process) instead of injecting the solution after water flooding (tertiary oil flooding). Before performing these types of core flooding experiments, viscosity, interfacial tension (IFT), and wettability alteration besides the effect of ionic liquids (ILs) on the IFT reduction are investigated at the presence of hydrolyzed polyacrylamide (HPAM) dissolved in SW. The results show the oil recovery of 63.5% by injecting SW/polymer while individual injection of water leading the oil recovery of 23.9% based on original oil in place (OOIP). Besides, further core-flooding experiments reveal that injecting SW/polymer solution modified by IL-based surfactants (SWPIL) enhances the recovery to 69.8 and 73.9% based on OOIP for 1-dodecyl-3-methylimidazolium chloride ([C12mim][Cl])) and 1-octadecyl-3-methylimidazolium chloride ([C18mim][Cl])) during the secondary stage. Finally, performing core-flooding experiments with a soaking time of 21 days reveal 87.0 and 89.3% of ultimate oil recovery which can be correlated to IFT reduction while the remained portions (13 and 10.7%) belong to the wettability alteration effect.

Biocompatible magnetite nanoparticles coated with ionic liquid-based surfactant as a hydrophilic sorbent for dispersive solid phase microextraction of cephalosporins prior to their quantitation by HPTLC

Extraction of highly hydrophilic compounds from biological fluids including urine or plasma samples is a dilemma due to high hydrophilicity of the matrix itself. The main aim of the current work is to explore the competence of ionic liquid (IL)-based surfactant-coated mineral oxide nanoparticles (NPs) in dispersive solid-phase microextraction (d-SPME) of highly hydrophilic analytes taking cefoperazone (CPZ) as a model analyte for the study. The IL-based surfactant coated Fe3O4 NPs is utilized as an innovative adsorbent for the separation and pre-concentration of CPZ after intramuscular injection (I.M) in rabbits. The utilized magnetite NPs were synthesized via simple and reliable co-precipitation procedure, which doesn’t require any air-free environment and depends on a single iron (III) salt. Characterization of the as-synthesized NPs was achieved by X-ray powder diffraction (XRD), Fourier transform infrared (FT-IR) and energy dispersive X-ray (EDX). Surface area measurements show that Fe3O4 NPs have large surface area of 75 m2 g−1. The developed approach utilizes the unique properties of the IL-based surfactant including multiple polar interaction types provided by the polar head in addition to merits of Fe3O4 nanoparticles, which include large adsorptive capacity and magnetic properties, to improve separation, save time, and achieve satisfactory recovery. Comprehensive study was developed for the factors, that affect the adsorption capacity such as pH, NPs amount, IL-based surfactant concentration, ionic strength, adsorption time, and desorption conditions. Moreover, the adsorption data was fitted to Langmuir and second-order kinetic models as reflected by the reasonable determination coefficients of 0.9319 and 0.9726, respectively. Under the optimized conditions, the developed approach achieves good correlation coefficient of 0.9975, and 0.9981 over linearity range of 0.7–12.0 and 4.0–50.0 µg mL−1 for both CPZ standard solutions and spiked rabbit plasma, respectively. It also provides good sensitivity expressed by the low values of limit of detection (LOD) of 0.2 and 1.2 µg mL−1 and limit of quantitation (LOQ) of 0.7 and 4.0 µg mL−1 for both the standard solutions and spiked plasma, respectively. The developed approach was also applied successfully for monitoring CPZ in rabbit plasma samples with satisfactory recovery % (83–110). In addition, a detailed pharmacokinetic study is performed where pharmacokinetic parameters of CPZ in rabbit plasma samples were calculated.

Synthesis and determination of Surface tension of 1-butyl-3-methylimidazolium lauroyl sarcosinate IL and Tween 80

Ionic liquids (ILs) have unique physicochemical properties. ILs with long carbon chains are called surface-active ILs, and they have surfactant properties. In this study, we synthesize (1-butyl-3-methylimidazolium lauroyl sarcosinate) [BMIM] [Lausar] IL that have surfactant properties. Nuclear magnetic resonance spectroscopy (NMR) was used to confirm the chemical structure of the synthesized IL. The surface tension of [BMIM] [Lausar] was determined that it was almost 37.1mN/m. Tween 80 is the most famous commercial surfactant, and we also determine the surface tension of Tween 80. Afterword, we make the binary mixture of Tween 80 and IL-based surfactants. Based on our results, we can conclude that Tween 80 and [BMIM] [Lausar] both reduced surface tension and have excellent surface properties when combining and can be used as surfactants in many sectors.

Evaluation of Structurally Different Ionic Liquid-Based Surfactants in a Green Microwave-Assisted Extraction for the Flavonoids Profile Determination of Mangifera sp. and Passiflora sp. Leaves from Canary Islands.

Aqueous solutions of ionic liquids (ILs) with surface active properties were used as extraction solvents, taking advantage of their impressive solvation properties, in a green microwave-assisted solid-liquid extraction method (IL-MA-SLE) for the extraction of flavonoids from passion fruit and mango leaves. The extraction method was combined with high-performance liquid chromatography and photodiode-array detection (HPLC-PDA) and optimized by response surface methodology using the Box-Behnken experimental design. Under optimum conditions, the extraction efficiency of six structurally different IL-based surfactants was evaluated. Thus, imidazolium-, guanidinium- and pyridinium-type ILs with different tailorable characteristics, such as side chain length and multicationic core, were assessed. The decylguanidinium chloride ([C10Gu+][Cl–]) IL-based surfactant was selected as key material given its superior performance and its low cytotoxicity, for the determination of flavonoids of several samples of Passiflora sp. and Mangifera sp. leaves from the Canary Islands, and using as target analytes: rutin, quercetin and apigenin. The analysis of 50 mg of plant material only required 525 µL of the low cytotoxic IL-based surfactant solution at 930 mM, 10.5 min of microwave irradiation at 30 °C and 50 W, which involves a simpler, faster, more efficient and greener method in comparison with other strategies reported in the literature for obtaining bioactive compounds profiles from plants.

Sustainable Micro-Scale Extraction of Bioactive Phenolic Compounds from Vitis vinifera Leaves with Ionic Liquid-Based Surfactants.

This paper proposes a new sustainable and simple strategy for the micro-scale extraction of phenolic compounds from grapevine leaves with analytical purpose. The method is based on a microwave-assisted solid-liquid extraction approach (MA-SLE), using an aqueous solution of an ionic liquid (IL)-based surfactant as extraction phase. The method does not require organic solvents, nor any clean-up step, apart from filtration prior to the injection in the analytical system. Two IL-based surfactants were evaluated, and the method was optimized by using experimental designs, resulting in the use of small amounts of sample (100 mg) and extraction phase (2.25 mL), low concentrations of the selected 1-hexadecyl-3-butyl imidazolium bromide IL (0.1 mM), and 30 min of extraction time. The proposed methodology was applied for the determination of the polyphenolic pattern of six different varieties of Vitis vinifera leaves from the Canary Islands, using high-performance liquid chromatography and photodiode array detection for the quantification of the compounds. The proposed MA-SLE approach was greener, simpler, and more effective than other methods, while the results from the analysis of the leaves samples demonstrate that these by-products can be exploited as a source of natural compounds for many applications.

Guanidinium ionic liquid-based surfactants as low cytotoxic extractants: Analytical performance in an in-situ dispersive liquid–liquid microextraction method for determining personal care products

The IL-based surfactant octylguanidinium chloride (C8Gu-Cl) was designed and synthetized with the purpose of obtaining a less harmful surfactant: containing guanidinium as core cation and a relatively short alkyl chain. Its interfacial and aggregation behavior was evaluated through conductivity and fluorescence measurements, presenting a critical micelle concentration value of 42.5 and 44.6mmolL−1, respectively. Cytotoxicity studies were carried out with C8Gu-Cl and other IL-based and conventional surfactants, specifically the analogue 1-octyl-3-methylimidazolium chloride (C8MIm-Cl), and other imidazolium- (C16MIm-Br) and pyridinium- (C16Py-Cl) based surfactants, together with the conventional cationic CTAB and the conventional anionic SDS. From these studies, C8Gu-Cl was the only one to achieve the classification of low cytotoxicity. An in situ dispersive liquid–liquid microextraction (DLLME) method based on transforming the water-soluble C8Gu-Cl IL-based surfactant into a water-insoluble IL microdroplet via a simple metathesis reaction was then selected as the extraction/preconcentration method for a group of 6 personal care products (PCPs) present in cosmetic samples. The method was carried out in combination with high-performance liquid chromatography (HPLC) and diode array detection (DAD). The method was properly optimized, requiring the use of only 30μL of C8Gu-Cl for 10mL of aqueous sample with a NaCl content of 8% (w/v) to adjust the ionic strength and pH value of 5. The metathesis reaction required the addition of the anion exchange reagent (bis[(trifluoromethyl)sulfonyl]imide − 1:1 molar ratio), followed by vortex and centrifugation, and dilution of the final microdroplet up to 60μL with acetonitrile before the injection in the HPLC-DAD system. The optimum in situ DLLME-HPLC-DAD method takes ∼10min for the extraction step and ∼22min for the chromatographic separation, with analytical features of low detection limits: down to 0.4μgL−1; high reproducibility: with RSD values lower than 10% (intra-day) and 16% (inter-day) for a spiked level of 15μgL−1; and an average enrichment factor of 89. The requirement of low volumes (30μL) of a low cytotoxic IL-based surfactant allows the method to be considered less harmful than other common analytical microextraction approaches.

Ionic liquids in enhancing the sensitivity of capillary electrophoresis: Off-line and on-line sample preconcentration techniques.

The popularity of ionic liquids (ILs) has grown during the last decade in enhancing the sensitivity of CE through different off-line or on-line sample preconcentration techniques. Water-insoluble ILs were commonly used in IL-based liquid phase microextraction, in all its variants, as off-line sample preconcentration techniques combined with CE. Water-soluble ILs were rarely used in IL-based aqueous two phase system (IL-ATPS) as an off-line sample preconcentration approach combined with CE in spite of IL-ATPS predicted features such as more compatibility with CE sample injection due to its relatively low viscosity and more compatibility with CE running buffers avoid, in some cases, anion exchange precipitation. Therefore, the attentions for the key parameters affecting the performance of IL-ATPSs were generally presented and discussed. On-line CE preconcentration techniques containing IL-based surfactants at nonmicellar or micellar concentrations have become another interesting area to improve CE sensitivity and it is likely to remain a focus of the field in the endeavor because of their numerous to create rapid, simple and sensitive systems. In this article, significant contributions of ILs in enhancing the sensitivity of CE are described, and a specific overview of the relevant examples of their applications is also given.

Ionic liquids versus ionic liquid-based surfactants in dispersive liquid–liquid microextraction for determining copper in water by flame atomic absorption spectrometry

ABSTRACTThis work compares the performance of dispersive liquid–liquid method (DLLME) as a prior step for determining copper by flame atomic absorption spectrometry (FAAS), when using the ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate (C4MIm-PF6) or the IL-based surfactant 1-hexadecyl-3-butylimidazolium bromide (C16C4Im-Br) as extractant solvents. For the water-insoluble C4MIm-PF6, the most conventional DLLME mode using acetonitrile as dispersive solvent was employed. For the water-soluble C16C4Im-Br, the in situ DLLME mode with lithium bis[(trifluoromethane)sulfonyl]imide (Li-NTf2) as metathesis reagent was employed. In both approaches, some effective parameters such as volumes of extractant and dispersive solvents, concentration of complexing agent, pH of sample solution, salting-out effect and final diluting solvent to ensure compatibility with FAAS, were properly optimised. The optimum conditions for the IL-DLLME method using C4MIm-PF6 were: 100 μL of neat C4MIm-PF6, 1 mL of acetonitrile, 10 mL of water, no control of pH for environmental waters, NaCl content of 23 g L−1, diethyl dithiocarbamate (DDTC) as complexing agent at 10 mg L−1 and final dilution of the micro-droplet with acetonitrile up to 70 µL. The optimum conditions for the in situ IL-DLLME method using C16C4Im-Br were: 0.8 mL of acetonitrile, 10 mL of water containing C16C4Im-Br at 25.2 mmol L−1, final dilution step of the micro-droplet with 200 µL of acetonitrile and remaining conditions as those of C4MIm-PF6. The analytical performance of both methods was similar, being slightly better for the IL-DLLME method using C4MIm-PF6, with limits of detection (LOD) of 3.3 µg L−1 (versus 5.1 µg L−1 when using C16C4Im-Br), precision values as intraday relative standard deviation (RSD in %) lower than 8.8% (being of 10% for the C16C4Im-Br method) and an enrichment factor of 54 (being 27 when using C16C4Im-Br). The DLLME-FAAS method with C4MIm-PF6 was used in the analysis of environmental waters with successful performance, with relative recoveries of 110% and 105%, and interday precision with RSD values of 21% and 7.4% for spiked levels of 60 and 160 µg L−1, respectively. The results obtained when analysing an urban wastewater sample coming from an inter-laboratory exercise was comparable to those obtained for other 93 laboratories. The method was also valid for the determination of Cu2+ in presence of foreign ions commonly found in natural waters.

Double salts of ionic-liquid-based surfactants in microextraction: application of their mixed hemimicelles as novel sorbents in magnetic-assisted micro-dispersive solid-phase extraction for the determination of phenols.

The use of mixed hemimicelles of ionic liquid (IL)-based surfactants in a magnetic-based micro-dispersive solid-phase extraction (m-μdSPE) approach is described. Not only is the symmetric monocationic IL-based surfactant 1,3-didodecylimidazolium bromide (C12C12Im-Br) studied for first time in m-μdSPE, but double-salt (DS) IL (DSIL)-based surfactants are also examined. Nine DSIL-based surfactants were formed by combination of C12C12Im-Br with other IL-based surfactants, including nonsymmetric monocationic and dicationic ILs combined at three different molar fractions. The analytical application was focused on the determination of a group of eight phenols, including bisphenolA, in water samples. The best results were obtained with the DSIL formed by C12C12Im-Br (molar fraction 0.5) and 1-hexadecyl-3-methylimidazolium bromide (C16MIm-Br), after proper optimization of the overall method in combination with high-performance liquid chromatography (HPLC) and diode-array detection (DAD). The optimum conditions for 100mL of water samples require a small amount (10mg) of Fe3O4 magnetic nanoparticles, a low content (5.0mg of C12C12Im-Br and 3.9mg of C16MIm-Br) of the selected DSIL, pH11, a sonication time of 2.5min, and an equilibration time of 5min with the aid of NdFeB magnets, followed by elution of phenols, evaporation, and reconstitution with 0.5mL of acetonitrile. The overall m-μdSPE-HPLC-DAD method is characterized for limits of detection down to 1.3μg · L(-1), intraday relative standard deviations lower than 13% (n = 3), and interday relative standard deviations lower than 17% (n = 9), with a spiking level of 15μg · L(-1); with enrichment factors between 15.7 and 141, and average relative recoveries of 99.9%.

Interfacial and aggregation behavior of dicationic and tricationic ionic liquid-based surfactants in aqueous solution

The interfacial and aggregation behavior of three dicationic and two tricationic ionic liquid-based (IL) surfactants in aqueous solutions have been carried out. The studied dicationic IL-based surfactants were 1,12-di(3-butylimidazolium)dodecane bromide ((C4Im)2C12-2Br), 1,12-di(3-decylimidazolium)dodecane bromide ((C10Im)2C12-2Br), and 1,12-di(3-hexadecylimidazolium)dodecane bromide ((C16Im)2C12-2Br). Two classes of trigonal tricationic surfactants containing triethylamine (Am) and 1,3,5-trimethylbenzene (Bn) cores were synthesized for first time and characterized, specifically, 3,3′,3″-octyl-1,1′,1″-(2-ethylamino) imidazolium bromide ((C8Im)3Am-3Br), and 3,3′,3″-octyl-1,1′,1″-(1,3,5)tris(methylene) benzene imidazolium bromide ((C8Im)3Bn-3Br). The critical micelle concentration (CMC) values and other aggregation parameters, including adsorption efficiency (pC20), surface tension at the CMC (γcmc), degree of dissociation (α), and the degree of counterion binding in the micelle (β) were obtained using a variety of techniques including surface tension, conductivity, and fluorescence measurements. For the first time, the aggregation numbers (Nagg) were also obtained for this group of surfactants. A study into the influence of acetonitrile on the stability and aggregation behavior of dicationic and tricationic IL-based surfactants was also undertaken. The CMC values of the dicationic surfactants clearly decrease as a function of the side chain, when the same linker is maintained. The CMC values of the tricationic surfactants were lower than analogous linear trimeric surfactants. For the novel tricationic surfactants, the effect of sodium salts (C6H5COONa, NaBr, and NaI) on the surface activity was also investigated. It was also observed that the surface activity parameters (pC20 and CMC/C20) of tricationic surfactants increased significantly in the presence of added electrolytes.

An in-situ extraction–preconcentration method using ionic liquid-based surfactants for the determination of organic contaminants contained in marine sediments

The determination of a group of organic contaminants from marine sediments samples including three polycyclic aromatic hydrocarbons, five alkylphenols (i.e., bisphenol-A or nonylphenol) and one paraben has been carried out using an extraction/preconcentration strategy with ionic liquid-based surfactants and high-performance liquid chromatography (HPLC) with diode array detection (DAD). Sediments are first extracted using two IL-based surfactants, specifically 1-hexadecyl-3-methyl imidazolium bromide (C16MIm–Br) and 1-hexadecyl-3-butyl imidazolium bromide (C16C4Im–Br), as the extraction media in a microwave-assisted extraction (MAE) procedure, followed by a novel in situ preconcentration method. The optimized MAE method requires 0.1g of sediment and 5mL of 40mM C16MIm–Br IL solution. The extracts are then centrifuged and filtered. The subsequent preconcentration in situ approach consists of the insolubilization of an IL-based surfactant formed by a metathesis reaction using the anion-exchange reagent lithium bis[(trifluoromethane)sulfonyl]imide (LiNTf2), which produces an analyte enriched IL microdroplet. The optimized in situ approach utilizes 4mL of the filtered extract, which are mixed with acetonitrile and 92μL of LiNTf2 solution (0.5gmL−1), heated, vortexed and centrifuged. The formed IL microdroplet is then simply diluted with acetonitrile (∼100μL) and injected in the chromatograph without any further clean-up steps. The overall extraction/preconcentration method requires approximately 25min in spite of dealing with complex solid samples, is nearly free of organic solvent (requires ∼900μL of acetonitrile per sample), and produces high preconcentration factors and quantification limits down to 0.04mgkg−1 using HPLC–DAD.

Ionic Liquid-Based Surfactants in Separation Science

A group of nearly forty-eight (48) of surfactants based on ionic liquids (ILs) has been described. The physicochemical and interfacial behavior for several of these IL-based surfactants has been reported since 2004. This review attempts to summarize the important applications that IL-based surfactants have had in analytical chemistry and separation science. Thus, they have been successfully used as extractant systems as substitutes to conventional organic solvents in extraction schemes, or by modifying the chemical structure of conventional extractant sorbents. The analytical performance of these novel IL-based surfactants has been shown to be better than conventional solvents and even better than conventional cationic surfactants. IL-based surfactants have also been used as mobile phase and stationary phase modifiers in high-performance liquid chromatography (HPLC), as modifiers of the electrokinetic chromatographic (EKC) medium, or as the micellar component in capillary electrophoresis (CE). Thus, IL-based surfactant methods constitute a promising and developing area within separation science.

A novel in situ preconcentration method with ionic liquid-based surfactants resulting in enhanced sensitivity for the extraction of polycyclic aromatic hydrocarbons from toasted cereals

A preconcentration procedure utilizing IL-based surfactants it is described for the first time. The procedure is based on transforming a water-soluble IL-based surfactant, 1-hexadecyl-3-butylimidazolium bromide (C16C4Im-Br), into a water-insoluble IL, 1-hexadecyl-3-butylimidazolium bis[(trifluoromethane)sulfonyl]imide (C16C4Im-NTf2), via a simple metathesis reaction. The preconcentration procedure is used in combination with a micellar microwave-assisted extraction (MMAE) method for the analysis of sixteen polycyclic aromatic hydrocarbons (PAHs) from toasted cereals. The obtained microdroplet of C16C4Im-NTf2 containing the extracted PAHs is then diluted with acetonitrile and injected into a high-performance liquid chromatograph (HPLC) employing UV–vis and fluorescence detection. This in situ preconcentration step highly improves the sensitivity of the MMAE despite the complexity of the solid matrix. The developed in situ preconcentration method exhibited almost quantitative extraction efficiencies (80–95% in average) for the PAHs studied, and good precision values (lower than 14%). The overall MMAE+in situ preconcentration method presented limits of detection down to 0.03μgkg−1.

Aqueous Dispersion, Surface Thiolation, and Direct Self-Assembly of Carbon Nanotubes on Gold

We report the efficient aqueous dispersion of pristine HiPco single-walled carbon nanotubes (SWNTs) with ionic liquid (IL)-based surfactants 1-dodecyl-3-methylimidazolium bromide (1) and 1-(12-mercaptododecyl)-3-methylimidazolium bromide (2), the thiolation of nanotube sidewalls with 2, and the controlled self-assembly of positively charged SWNT-1,2 composites on gold. Optical absorption spectra and resonance Raman (RR) data of obtained aqueous SWNT-1,2 dispersions are consistent with debundled and noncovalently functionalized nanotubes whose electronic properties have not been disturbed. Additionally, the dispersion of pristine nanotube material with surfactants 1 and 2 leads to a high degree of purification from carbonaceous particles. The chiralities of the 14 smallest semiconducting HiPco SWNTs in resonance with Raman excitation at 1064 nm (1.165 eV) were determined in SWNT-2 aqueous dispersion using UV-vis-NIR and RR spectra. X-ray photoelectron spectroscopy (XPS) and surface-enhanced resonance Raman scattering (SERRS) spectroscopy of SWNT-2 submonolayers on gold verified the encapsulation of individualized SWNTs with IL surfactants, the cleavage of S-S disulfide bonds formed in aqueous SWNT-2 suspensions, and the direct chemisorption of the SWNT-2 composite on bare gold via the Au-S bond. Aqueous dispersions of SWNTs with IL-based surfactants add biofunctionality to carbon nanotubes by imparting the positive surface charge necessary for interactions with cell membranes. Our technique, which purifies pristine nanotube material and produces water-soluble, positively charged nanotubes with pendent surface-active thiol groups, may also be translated to other carbon nanotubes and carbon nanostructures. Self-assembled, positively charged submonolayers of SWNTs can be further used for applications in cell biology and sensor technology.