Critical Micelle Concentration Of Surfactant Research Articles

Engineering a Surfactant Trap via Postassembly Modification of an Imine Cage.

Imine self-assembly stands as a potent strategy for the preparation of molecular organic cages. However, challenges persist, such as water insolubility and limited recognition properties due to constraints in the application of specific components during the self-assembly process. In this study, we addressed these limitations by initially employing a locking strategy, followed by a postassembly modification. This sequential approach enables precise control over both the solubility and host-guest properties of an imine-based cage. The resulting structure demonstrates water solubility and exhibits an exceptional capacity to selectively interact with anionic surfactants, inducing their precipitation. Remarkably, each cage precipitates 24 equiv of anionic surfactants even at concentrations much lower than the surfactant's critical micelle concentration (CMC), ensuring their complete removal. Molecular simulations elucidate how anionic surfactants specifically interact with the cage to facilitate aggregation below the surfactant CMC and induce precipitation as a micellar cross-linker. This innovative class of cages paves the way for the advancement of materials tailored for environmental remediation.

Predicting the Temperature Dependence of Surfactant CMCs Using Graph Neural Networks.

The critical micelle concentration (CMC) of surfactant molecules is an essential property for surfactant applications in the industry. Recently, classical quantitative structure-property relationship (QSPR) and graph neural networks (GNNs), a deep learning technique, have been successfully applied to predict the CMC of surfactants at room temperature. However, these models have not yet considered the temperature dependence of the CMC, which is highly relevant to practical applications. We herein develop a GNN model for the temperature-dependent CMC prediction of surfactants. We collected about 1400 data points from public sources for all surfactant classes, i.e., ionic, nonionic, and zwitterionic, at multiple temperatures. We test the predictive quality of the model for the following scenarios: (i) when CMC data for surfactants are present in the training of the model in at least one different temperature and (ii) CMC data for surfactants are not present in the training, i.e., generalizing to unseen surfactants. In both test scenarios, our model exhibits a high predictive performance of R2 ≥ 0.95 on test data. We also find that the model performance varies with the surfactant class. Finally, we evaluate the model for sugar-based surfactants with complex molecular structures, as these represent a more sustainable alternative to synthetic surfactants and are therefore of great interest for future applications in the personal and home care industries.

Experimental and data-driven analysis for predicting nanofluid performance in improving foam stability and reducing mobility at critical micelle concentration

Application of surfactant-based foam flooding is an effective approach to reduce mobility and control early breakthrough. Despite the proper performance of surfactant-based foams in decreasing the channeling of the flooded gas and water, high pressure, high temperature, and high salinity of the reservoirs put some limitations on the foam flooding efficiency. Nanoparticles are used to improve the quality of the foams, enhance stability, and transcend the limitations. Although there are many benefits of using nanoparticles in foam flooding, their performance at surfactant critical micelle concentration (CMC) is not fully investigated and the optimum nanoparticle concentration is not specified. In this study, an experimental investigation using nanosilica with surfactants at CMC to improve the stability (half-life) and mobility reduction factor (MRF) has been conducted. Furthermore, data from the literature were collected and analyzed to evaluate the change in MRF and stability for a nanofluid-based foam at CMC. Both experimental results and literature data showed that application of nanofluid-based foam is a successful approach to develop a more stable foam with lower mobility. Nanoparticle (NP) concentration is the dominant parameter at different salinities and temperatures that affects foam flow through porous media. The range of 0.2–0.4 wt% is the optimum nanoparticle concentration to develop a strong foam with acceptable performance in controlling mobility.

Interaction of sodium dodecyl sulfate and cetyl trimethyl ammonium bromide surfactants with amantadine drug in aqueous solution: Conductometric and molecular dynamics studies

In the present work, the interaction of sodium dodecyl sulfate and cetyl trimethyl ammonium bromide surfactants with amantadine drug in aqueous solutions was studied using conductometric measurements and molecular dynamic simulation. Conductometric data were used to determine the critical micelle concentration (CMC) values of surfactants on various amantadine aqueous solutions at T= (300.2, 310.2 and 320.2) K and 0.1 MPa. The effect of amantadine concentration (m = 0.0005, 0.0010, 0.0015 and 0.002 mol.kg−1) on CMC of sodium dodecyl sulfate and cetyl trimethyl ammonium bromide surfactants was investigated. It was observed the CMC value of sodium dodecyl sulfate surfactant increases with increasing of amantadine concentration whereas the CMC values of cetyl trimethyl ammonium bromide surfactant decrease with increasing of amantadine concentration at the same temperature. Then, the thermodynamic properties such as standard Gibbs free energy, enthalpy, and entropy for micellization in aqueous solutions were determined. In addition, molecular dynamic simulation was carried out to understand the interaction sodium dodecyl sulfate and cetyl trimethyl ammonium bromide surfactants with amantadine at the molecular level and microscopic interactions. The root-mean-square deviations and electrostatic, hydrogen binding and hydrophobic interactions were determined by MD simulations. It was seen, the electrostatic and hydrogen bonding interactions play a crucial role in sodium dodecyl sulfate and amantadine aqueous system. The obtained results showed the simulation and experimental data are in agreement with each other.

Synergistic effects between a non-ionic and an anionic surfactant on the micellization process and the adsorption at liquid/air surfaces.

Predicting the behaviour of solutions with surfactants of significantly different critical micelle concentration (CMC) values remains a challenge. The study of the molecular interactions within micelles and interfaces in surfactant combinations used in everyday products is essential to understand these complex systems. In this work, the equilibrium and dynamic surface tension in the presence of mixed non-ionic (tristyrylphenol ethoxylates) and anionic (sodium benzene sulfonate with alkyl chain lengths of C10-C13) surfactants, commonly encountered as delivery systems in agrochemicals, were studied and their CMC values were determined. For the surfactant mixtures, four molar ratios were examined: nEOT/nNaDDBS = 0.01, 0.1, 1, 4 and two different cases were analysed, the premixed and the add one by one surfactant. The surface tension for single surfactants stabilised quickly, while the mixtures needed a long time to reach equilibrium; up to 15 h for the premixed mixtures and 40 min when surfactants were added one by one. The CMC values for the nEOT/nNaDDBS = 0.01, 0.1 premixed surfactant mixtures were found to be in between the CMC values of the single surfactants, but those for the nEOT/nNaDDBS = 1 and 4 mixtures were lower than the CMCs of both single surfactants. Calculations based on the regular solution theory suggested that there are attractive forces in the mixed micelles and at the interface layers, while the supramolecular assemblies in the bulk (i.e., micelles) and at interfaces (surfactant films) are preferentially enriched in EOT.

Exploring the effects of interactions between nonylphenol ethoxylate and ionic surfactants on interfacial and foaming properties

Nonylphenol ethoxylate (NPE-9) is a widely recognized non-ionic surfactant that finds extensive applications in various industries, including detergency, emulsification, and agriculture. Combining NPE-9 with an ionic surfactant reflects an inexpensive and highly promising approach for enhancing the efficacy of NPE-9. This study explores the molecular interactions between NPE-9 and ionic surfactants (SDS and CTAB) and examines the impact of these interactions on interfacial properties and foaming. The micellization parameters, including the critical micelle concentration (CMC), degree of counterion binding (β), degree of counterion dissociation (α), and change in free energy of micellization (ΔGmic), were investigated for sodium dodecyl sulfate (SDS) and cetyltrimethylammonium bromide (CTAB) in the presence and absence of NPE-9, using conductometric measurements. The combined effect of NPE-9 and an ionic surfactant resulted in a synergistic interaction, reducing the CMC of the ionic surfactant, and promoting the formation of micelles. The interaction between NPE-9 and ionic surfactants at the air/water interface was investigated using surface tension measurements. The interfacial properties improved through the competitive adsorption and synergistic effect observed between NPE-9 and an ionic surfactant. In this context, the surface tension data of NPE-9 is utilized to calculate interfacial parameters, including maximum surface excess concentration (Γmax), minimum area per molecule (Amin), and surface effectiveness (π). Adding SDS and CTAB to NPE-9 solutions resulted in a notable enhancement in foamability and foam stability. The utilization of various techniques consistently produced improvements in the interfacial and foaming properties of NPE-9.

Carbon quantum dots as fluorescent probes in the measurement of the critical micelle concentration of surfactants

The critical micelle concentration (CMC) is one main parameter of surfactants, so an accurate, rapid, and convenient method for CMC determination is of great significance for surfactant applications. In this paper, three samples of carbon quantum dots (CQDs) with different fluorescence properties were developed as fluorescent probes for the CMC determination of CTAB, SDS, Triton X-100, perfluoro OBS and Pluronics® P-123. The fluorescence excitation and emission spectra of a constant amount of the CQDs in different concentrations of the surfactant solution were recorded, and then the CMC values of the surfactant were deduced from the fluorescence intensity change and the Stokes shift variation. The obtained CMC data using three samples of the CQDs agree well with those in the published literature. It is also demonstrated that in the micellization process the interaction between the CQDs and the surfactant molecules is complicated, because the fluorescence properties of the CQDs are found to be related to the characteristics of the CQDs, the head group type of ionic surfactants, the chemical structure between the hydrophobic and hydrophilic segment, and the chemical nature of the hydrophobic chains of the surfactants. So, the CQDs are demonstrated to be located at the palisade layer in the surfactant micelles due to the surface-attached polar groups on the CQDs although the CQDs are mainly hydrophobic as fluorescent probes. The fluorescent CQDs are considered to be new choices of the fluorescent probes in the facile CMC measurement of the surfactants.

Synthesis and surface activity of novel amino acid surfactants

AbstractAmino acid surfactants (AASs) based on environmentally friendly biomasses have the characteristics of renewable, easy biodegradation, antibacterial and low toxicity, and have been widely used in daily chemicals, pharmaceuticals, and other fields. This study concerned the use of octanal and amino acids as raw materials. In addition, seven types of amino acid‐based surfactants, through Collins reagents, Wittig‐Hornor reaction, and aza‐Micheal addition reaction, and amino acid head groups were connected with the alkyl chain by the CN bond. The structures were confirmed by infrared spectroscopy (FT‐IR) and nuclear magnetic resonance spectroscopy (1HNMR). Its surface activity and adsorption properties are evaluated. The physical properties of amino acid‐based surfactants were tested by surface tension and dynamic contact angle. The results demonstrated that histidine‐based amino acid surfactant (C8His) has the lowest critical micelle concentration (CMC) and surface tension at CMC (γCMC), 0.39 mmol L−1 and 28.79 mN L−1, respectively. Amino acid residues contribute to reducing the critical micelle concentration of surfactant. The interfacial adsorption of glycine‐based amino acid surfactant (C8Gly) significantly improved with the increase in temperature, so the surface tension decreased significantly. In addition, sodium chloride could effectively enhance the interfacial adsorption, and the gas–liquid interfacial tension and contact angle of AASs decrease.

Facile determination of surfactant critical micelle concentration through dried drop “coffee-ring” image analysis

Surfactants serve a myriad uses as key components of household cleaning, personal care, and cosmetics products, and they are important too in the food, textiles, plastics, oil, agrochemical, and pharmaceutical industries. The majority of those currently in use, however, are fossil fuel-derived and are environmentally unfriendly and/or bio-incompatibly toxic/irritant. There are significant efforts thus now expended in the search for alternatives that are generally “greener”. The concentration at which such compounds self-assemble to form micelles – their so-called critical micelle concentration – is one of their key physicochemical characteristics, and the experimental determination of this is central to their development both as analytical tools and as commercial materials. In the following report a methodology is presented that provides for a fast, non-expensive, and potentially high throughput means to determine surfactant critical micelle concentration, utilizing a simple dried drop “coffee-ring” image analysis.

Effect of hydrophobic chain length on the properties of polycarboxylate polymeric surfactants

In this work, a series of polycarboxylate polymeric surfactants were designed and synthesized from acrylate monomers with different alkyl chain lengths (alkyl chain lengths of 1, 4, 6, 12, 18), epoxy succinic acid (ESA), acrylic acid (AA) and 2-acrylamide-2-methylpropane sulfonic acid (AMPS). Their structures were confirmed by FT-IR, 1H NMR and GPC. A series of surfactant parameters, including critical micelle concentration (CMC), minimum surface tension, surface tension reduction at critical micelle concentration (Πcmc), surface tension reduction efficiency (pC20), etc, were obtained by surface activity test. The results showed that with the increase of the alkyl chain length of acrylate, surface tension and CMC of polycarboxylate polymeric surfactants gradually decreased. When the alkyl chain length of acrylate monomer was 12, the surface tension of polycarboxylate polymeric surfactants was the lowest, which was 32.6 mN/m. The results of TG, DLS and TEM showed that with the increased of the alkyl chain length of the acrylate, the micellar size of polycarboxylate polymeric surfactants decreased regularly. Meanwhile, the foaming, wetting and emulsifying properties of polycarboxylate polymeric surfactants were positively correlated with the alkyl chain length of the acrylate. The dispersing ability of polycarboxylate polymeric surfactants for calcium carbonate was 101.5 mg/g, which can dispersed Fe2O3 fouling to less than 1 μm under the condition of 0.6 g/L.

Structure-based modeling of critical micelle concentration (CMC) of anionic surfactants in brine using intelligent methods

Critical micelle concentration (CMC) is one of the main physico-chemical properties of surface-active agents, also known as surfactants, with diverse theoretical and industrial applications. It is influenced by basic parameters such as temperature, pH, salinity, and the chemical structure of surfactants. Most studies have only estimated CMC at fixed conditions based on the surfactant’s chemical parameters. In the present study, we aimed to develop a set of novel and applicable models for estimating CMC of well-known anionic surfactants by considering both the molecular properties of surfactants and basic affecting factors such as salinity, pH, and temperature as modeling parameters. We employed the quantitative-structural property relationship technique to employ the molecular parameters of surfactant ions. We collected 488 CMC values from literature for 111 sodium-based anionic surfactants, including sulfate types, sulfonate, benzene sulfonate, sulfosuccinate, and polyoxyethylene sulfate. We computed 1410 optimized molecular descriptors for each surfactant using Dragon software to be utilized in the modelling processes. The enhanced replacement method was used for selecting the most effective descriptors for the CMC. A multivariate linear model and two non-linear models are the outputs of the present study. The non-linear models were produced using two robust machine learning approaches, stochastic gradient boosting (SGB) trees and genetic programming (GP). Statistical assessment showed highly applicable and acceptable accuracy of the newly developed models (RSGB2 = 0.999395 and RGP2 = 0.954946). The ultimate results showed the superiority and greater ability of the SGB method for making confident predictions.

Role of Polyanions and Surfactant Head Group in the Formation of Polymer-Colloid Nanocontainers.

This study was aimed at the investigation of the supramolecular systems based on cationic surfactants bearing cyclic head groups (imidazolium and pyrrolidinium) and polyanions (polyacrylic acid (PAA) and human serum albumin (HSA)), and factors governing their structural behavior to create functional nanosystems with controlled properties. Research hypothesis. Mixed PE-surfactant complexes based on oppositely charged species are characterized by multifactor behavior strongly affected by the nature of both components. It was expected that the transition from a single surfactant solution to an admixture with PE might provide synergetic effects on structural characteristics and functional activity. To test this assumption, the concentration thresholds of aggregation, dimensional and charge characteristics, and solubilization capacity of amphiphiles in the presence of PEs have been determined by tensiometry, fluorescence and UV-visible spectroscopy, and dynamic and electrophoretic light scattering. The formation of mixed surfactant-PAA aggregates with a hydrodynamic diameter of 100-180 nm has been shown. Polyanion additives led to a decrease in the critical micelle concentration of surfactants by two orders of magnitude (from 1 mM to 0.01 mM). A gradual increase in the zeta potential of HAS-surfactant systems from negative to positive value indicates that the electrostatic mechanism contributes to the binding of components. Additionally, 3D and conventional fluorescence spectroscopy showed that imidazolium surfactant had little effect on HSA conformation, and component binding occurs due to hydrogen bonding and Van der Waals interactions through the tryptophan amino acid residue of the protein. Surfactant-polyanion nanostructures improve the solubility of lipophilic medicines such as Warfarin, Amphotericin B, and Meloxicam. Surfactant-PE composition demonstrated beneficial solubilization activity and can be recommended for the construction of nanocontainers for hydrophobic drugs, with their efficacy tuned by the variation in surfactant head group and the nature of polyanions.

Micellization thermodynamics as a function of the temperature of a cationic zwitterionic dodecyl phosphocholine and anionic sodium dodecyl sulfate mixed micelles with fluorometry

As fluorescence parameters such as lifetime, quantum yield, anisotropy and polarisation quantum are extremely sensitive to fluorophores’ microenvironmental changes, changes in the properties of the fluorescence probe have been widely used to study hydrophobic interactions in protein and membrane biology. The current study determines the critical micelle concentration (CMC) of mixed micelles of sodium dodecyl sulfate (SDS) and cationic surfactant N-dodecyl phosphocholine (DPC) based on fluorescence intensity measurements. biomolecular structure analysis and dynamics revealed through the measure of changes in the nanosecond time range. As the temperature rises, the onset of micellization tends to occur at higher concentrations. It was measured versus micelle concentration over a temperature range of (288–338) K. The obtained results were used to estimate the micellization thermodynamic parameters. Surfactant CMC drops to a minimum (T = 308 K) and then rises with temperature forming a parabolic curve as a function of temperature, according to experimental data. The CMCs are first correlated by a polynomial equation to determine the enthalpy of micellization. Both Delta {H}_{mathrm{mic}} and Delta {S}_{mathrm{mic}} appear to decrease monotonically as temperature rises. ΔGmic is negative, indicating that the micellization process is exothermic and favorable. The compensation temperature (Tc) ranged from (313–318) K by linear regression over the whole temperature range and for DPC, SDS, and mixed micelles together.

Interfacial Structure and Electrostatics Related to Solute Activity in a Model Anionic-Surfactant/Polymer Self-Assembly.

Polymer/surfactant composites are used in industry as an excipient for water-insoluble solutes. Such enhanced dissolution ability of composite media is related to the spontaneous formation of pre-micellar polymer surfactant aggregates (PS) at a magnitude of order lower than the surfactant critical micelle concentration in water. Combining electrochemical and spectroscopic studies, we investigate the microscopic interfacial structure (i.e., interface electrostatics and surface polarity) of PS formed in composite media. We establish that in a composite system, a mere change in the polymer concentration at a fixed surfactant concentration makes possible to regulate the counter-ion binding ability, surface potential, surface charge density, packing and surface polarity of the PS interface. Our study shows that the higher dissolution of water-insoluble nonionic solutes in composite media is driven by the depressing of surface charge density and polarity of the PS interface. A similar modulation of the PS interface acts as a barrier for the passive relocation of water-soluble charged solutes into the PS pseudo-phase. The time-resolved fluorescence anisotropy study allows us to underline the effect of surface charge modulation on the dynamical aspects of solutes at the PS interface.

Surfactant in a Polyol-CO2 Mixture: Insights from a Classical Density Functional Theory Study.

Silicone-polyether (SPE) surfactants, made of a polydimethyl-siloxane (PDMS) backbone and polyether branches, are commonly used as additives in the production of polymeric foams with improved properties. A key step in the production of polymeric foams is the nucleation of gas bubbles in the polymer matrix upon supersaturation of dissolved gas. However, the role of SPE surfactants in the nucleation of gas bubbles is not well understood. In this study, we use classical density functional theory to investigate the effect of an SPE surfactant on the nucleation of CO2 bubbles in a polyol foam formulation. We find that the addition of an SPE surfactant leads to a ∼3-fold decrease in the polyol-CO2 interfacial tension at the surfactant's critical micelle concentration. Additionally, the surfactant is found to reduce the free energy barrier and affect the minimum free energy pathway (MFEP) associated with CO2 bubble nucleation. In the absence of a surfactant, a CO2-rich bubble nucleates from a homogeneous CO2-supersaturated polyol solution by following an MFEP characterized by a single nucleation barrier. Adding a surfactant results in a two-step nucleation process with reduced free energy barriers. The first barrier corresponds to the formation of a spherical aggregate with a liquid-like CO2 core. This spherical aggregate then grows into a CO2-rich bubble (spherical aggregate with a vapor-like CO2 core) of a critical size representing the second barrier. We hypothesize that the stronger affinity of CO2 for PDMS (than polyether) stabilizes the spherical aggregate with the liquid-like CO2 core, leading to a lower free energy barrier for CO2 bubble nucleation. Stabilization of such an aggregate during the early stages of the nucleation may lead to foams with more, smaller bubbles, which can improve their microstrustural features and insulating abilities.

A Review on Interactions between Amino Acids and Surfactants as Well as Their Impact on Corrosion Inhibition.

Amino acid-surfactant interactions are central to numerous studies because of their increased effectiveness in chemical, biological, household and industrial use. This review will focus on the impact and effect of the physicochemical properties, temperature, pH, and surfactant chain length of the amino acid for detailed exploration of amino acids and surfactants in aqueous medium. The impact of cosolvent on self-aggregation, critical micelle concentration (CMC), and binding affinity with other biomolecules, as well as amino acid-surfactant interactions, are the epicenters. The results show that increasing the temperature causes negative enthalpy for ionic surfactants and micellization, implying that micellization and amino acids are thermodynamically spontaneous and exothermic, accompanied by positive entropy. As these physicochemical studies are additive, the amino acid and ionic surfactant interactions provide clues on protein unfolding and denaturation under different media, which further changes with a change in physiological conditions like pH, cosolvent, chain length, and temperature. On varying the pH, the net charge of the amino acid also changes and, subsequently, the binding efficiency of the amino acids to the surfactants. The presence of cosolvent causes a lowering in the hydrophobic chain, which changes the surfactant's CMC. At a reduced CMC, the hydrophobic characteristic of amino acid-surfactant associations is amplified, leading to rapid denaturation of proteins that act as propulsion under the influence of extended chain surfactants. Amino acids are one of the most intriguing classes of chemicals that produce high inhibitory efficacy. Amino acids are also a component of proteins and therefore, found in a significant part of the human body, further making them a promising candidate as corrosion inhibitors. In this review article, authors have also focused on the collection and investigation for application of amino acid-surfactant interactions in corrosion inhibition. Various predictive studies/in silico studies are also reported by many research groups, such as density functional theory (DFT) calculations and molecular dynamics simulations to obtain tentative electronic, structural, and physiochemical characteristics like energies of the highest occupied molecular orbitals and lowest unoccupied molecular orbitals, binding energy, Gibb's free energy, electronegativity, polarizability, and entropy. In silico studies are helpful for the mechanism predictions of the process occurring on metal surfaces.

Regular solution theory for nonlinear composition dependency of enantioselectivity by mixed micelle

Mixtures of chiral and achiral building blocks of supramolecules exhibit interesting cooperative properties, as indicated by the nonlinear relationship between chiral properties and the mole fraction of chiral building blocks. However, the nonlinear composition dependence of the chiral recognition capability of spherical mixed micelles is poorly understood. This study hypothesized that the phenomenon could be described by the regular solution theory reported to be able to describe critical micelle concentration (CMC) and partition coefficients of the mixed micelle by interaction parameters β and B, respectively. The CMC and mole fraction of chiral surfactant in the mixed micelle were simulated by using the theory of varying β and CMC of the two surfactants. Equations that describe the enantioselectivity are newly derived in this work, and the dependency of the enantioselectivity on B was studied in detail. The regular solution theory was applied to the mixed micellar electrokinetic chromatography (MEKC) for the first time. It was found that the formula can describe the nonlinear composition dependency of the enantioselectivity of the mixed MEKC. The partition coefficient determined by MEKC was in agreement with the β versus B relation, which was previously reported.

Synthesis of Highly Conductive Poly(3-hexylthiophene) by Chemical Oxidative Polymerization Using Surfactant Templates.

Poly(3-hexylthiophene) (P3HT) was systematically synthesized by chemical oxidative polymerization in chloroform with ferric chloride (FeCl3) as the oxidizing agent and various surfactants of the shape templates. The effects of 3HT: FeCl3 mole ratios, polymerization times, and surfactant types and concentrations on the electrical conductivity, particle shape and size were systematically investigated. Furthermore, dodecylbenzenesulfonic acid (DBSA), p-toluenesulfonic acid (PTSA), sodium dodecyl sulfate (SDS), and sodium dioctyl sulfosuccinate (AOT) were utilized as the surfactant templates. The P3HT synthesized with DBSA at 6 CMC, where CMC stands for the Critical Micelle Concentration of surfactant, provided a higher electrical conductivity than those with PTSA, SDS and AOT. The highest electrical conductivity of P3HT using DBSA was 16.21 ± 1.55 S cm−1 in which the P3HT particle shape was spherical with an average size of 1530 ± 227 nm. The thermal analysis indicated that the P3HT synthesized with the surfactants yielded higher stability and char yields than that of P3HT without. The P3HT_DBSA electrical conductivity was further enhanced by de-doping and doping with HClO4. At the 10:1 doping mole ratio, the electrical conductivity of dP3HT_DBSA increased by one order of magnitude relative to P3HT_DBSA prior to the de-doping. The highest electrical conductivity of dP3HT_DBSA obtained was 172 ± 5.21 S cm−1 which is the highest value relative to previously reported.

Performance evaluation of deep eutectic solvent for surfactant polymer flooding

Surfactant polymer (SP) flooding is among the most efficient and widely accepted chemical enhanced oil recovery (EOR) processes which involves slug injection containing a polymer and surfactant. This work is aimed at understanding the effect of different deep eutectic solvents (DESs) as an additive for EOR. For this, two different DES have been synthesized, having different hydrogen bond donors and acceptors and their effect on EOR was investigated. The results show that the addition of DESs as surfactant additives significantly improves flooding performance. The addition of DES1 and DES2 at critical micelle concentration (CMC) reduced the surface tension of water by 47% and 43%, respectively. The interfacial tension was drastically reduced upon the addition of DES. Also, DES molecules were found to affect the micellization concentration of surfactants. The addition of 1000 ppm of DES1 and DES2 reduced the CMC of surfactant by 17% and 9% respectively. In addition, DESs reduced the surfactant adsorption by 34% and 22% for DES1 and DES2, respectively. These results show that prepared DESs are highly efficient and outperformed the conventional [C12mim][Cl] and [C4mim][PF6] ionic liquids. The addition of DESs further enhanced the cumulative oil recovery for surfactant polymer flooding.

Application of a novel natural surfactant extracted from Avena Sativa for enhanced oil recovery during low salinity water flooding: Synergism of natural surfactant with different salts

The use of green, eco-friendly, efficient, and sustainable surfactants for enhanced oil recovery (EOR) is of great importance. In this study, a novel and unique natural surfactant was extracted from Avena Sativa (AS) plant commonly known as oat, to be used for EOR applications. The extracted saponin as a surfactant agent was confirmed using TGA, FESEM, 1H NMR, CHNS, and FT-IR analyses. The physico-chemical characteristics showed that the extracted nonionic surfactant from AS is very efficient and stable to be used for EOR applications. In order to have a better understating of the role of each ion during low salinity (LoSal) water flooding, nine different salts including NaCl, Na2SO4, CaCl2, MgSO4, MgCl2, K2SO2, KCl, NaHCO3, and Na2CO3 with constant ionic strength of 40.517 × 10-3, which is equal to the ionic strength of 2000 ppm diluted seawater (DSW2000) were prepared and tested in this study. The interfacial tension (IFT) measurement results showed that the critical micelle concentration (CMC) value of the natural surfactant is 4000 ppm. The IFT value of the natural surfactant at its CMC point was 6.45 and 3.65 mN/m for deionized water (DIW) and DSW2000, respectively. In addition, the IFT results showed that the CMC value of the natural surfactant was very effective with different salts in the range of LoSal water. Among all the tests performed by various salts, Na2CO3 was the most compatible salt with the natural surfactant in terms of IFT reduction (1.38 mN/m), while MgSO4 salt had the least impact on IFT reduction (6.63 mN/m). Moreover, the contact angle results reduced significantly when the CMC of the natural surfactant was used and reached the point of 38.28°, 55.12°, and 82.60° for Na2CO3, DSW2000, and MgSO4 salts, respectively. Furthermore, the most stable and the least stable emulsion tests were produced when the natural surfactant was mixed with Na2CO3 and MgSO4, respectively. The core flooding results showed that the injection of 5 PVs of the natural surfactant at the CMC point prepared in Na2CO3 as tertiary recovery increased the oil recovery factor (RF) by 28.89%.