Different Types Of Surfactants Research Articles

Formulation development and visualized investigation of temperature-resistant and salt-tolerant surfactant-polymer flooding to enhance oil recovery

As a tertiary oil recovery technique with broad application prospects, surfactant-polymer flooding can significantly improve sweep efficiency and enhance oil recovery, while eliminate the negative effects of alkali thoroughly. However, for most oil reservoirs abroad, belonging to marine carbonate reservoirs with high temperature and high salt content, SP flooding is largely limited. In this paper, the surface (interface) chemical properties of different types of surfactants were evaluated to select a mixed surfactant system with better performance and synergistic effect. And experiments on the physicochemical properties evaluation of polymers were performed to select a more suitable polymer. On this basis, the formulation of the surfactant-polymer binary composite system was optimized and the performance was evaluated. A visualized model was adopted to study the process of SP flooding, which vividly reflected the interaction of chemical agents with crude oil and the migration of chemical agents in porous media, as well as macroscopic and microscopic EOR mechanisms of SP Flooding. The results showed that Hexadecyl dimethyl carboxybetaine (C16HSB), heavy alkyl the linear alkylated diphenylmethane sulfonate (C14-DSDM) and the hydrophobically modified polyacrylamide-based novel functional polymer GT-1 were selected. The optimized formulation of the SP flooding system was selected for 2000 mg/L GT-1 + 3000 mg/L C14-DSDM + 1000 mg/L C16HSB, which showed higher apparent viscosity and lower interfacial tension (7.2 × 10−3 mN/m) under the condition of 70 °C and 9780.5 mg/L formation water salinity. The system showed a certain resistance to temperature and salt, and stability under the conditions of temperature below 80 °C and salinity below 40000 mg/L and an EOR value of 31.2% in the visualized displacement experiment. Surfactants in the SP flooding system can emulsify the residual oil into spherical and flocculent emulsions, which are then stripped, drawn into filaments, and easily motivated. The retention of more polymer molecules in the throat causes the intermolecular association of polymer molecules to form a denser network structure, which plays an important role in increasing flow resistance and changing the direction of liquid flow, and its viscoelasticity contributes to the discharge of residual oil. Under the synergistic effect of surfactants and polymer, hydrodynamic residual oil, membrane residual oil, and residual oil droplets can be mobilized, thus beneficial to enhance oil recovery.

Significance of surface excess concentration in the kinetics of surfactant-induced pore wetting in membrane distillation

Failure of membrane distillation (MD) due to pore wetting by amphiphilic molecules has recently received growing interests because it is a critical challenge to overcome for MD to be applicable for treating unconventional feed water. Recent MD studies using feed solutions containing surfactants have elucidated fundamental mechanism of wetting and generated practical solutions for wetting mitigation. However, what remains unclear is the impact of surfactant species on pore wetting kinetics. Based on a recently developed kinetic model for surfactant-induced pore wetting in MD, we hypothesize that the surface excess concentration of a surfactant is the most important surfactant property in affecting the pore wetting kinetics. In this study, we performed controlled MD wetting experiments using seven different types of surfactants and measured their respective breakthrough time as a quantitative metric for wetting kinetics. Our experiments reveal a good linear correlation between the surface excess concentration and breakthrough time for most but one tested surfactant. When surface excess concentration and diffusion coefficient are both considered, the model-simulated breakthrough time matches the experimentally measurement remarkably well for all tested surfactants.

Improving Oil Recovery in the Wolfcamp Reservoir by Soaking/Flowback Production Schedule With Surfactant Additives

Summary Improving oil recovery from unconventional liquid reservoirs (ULRs) is a major challenge. We have demonstrated in previous laboratory studies the effect of surfactants on spontaneous imbibition and oil recovery by means of wettability alteration and interfacial-tension (IFT) reduction. Thereby, fracture-treatment performance and consequently oil recovery could be improved by adding surfactants to stimulation fluids when a soaking/flowback production schedule is applied. This study evaluates the ability of different groups of surfactants to improve oil recovery in ULRs by experimentally simulating the fracture treatment to represent surfactant imbibition in a ULR core fracture during soaking and flowback. In addition, we analyze the effects of wettability and IFT alteration as well as surfactant adsorption on the process. A coreflooding system was combined with the computed-tomography (CT) scanner to dynamically visualize the fluid movement as it penetrates the ULR sample in real time as well as compare oil recovery between surfactants and water without additive. Wolfcamp sidewall cores were longitudinally fractured and loaded into an aluminum/carbon-composite core holder. Two different types of surfactants—anionic and nonionic/cationic—as well as water without surfactants were injected through the fractures at reservoir conditions to evaluate their effectiveness in penetrating into the fractures and recovering oil from a ULR core. Then, a soaking/flowback production scheme was used to simulate fracture treatment and flowback. Changes in core wettability and IFT were determined by contact-angle (CA) and pendant-drop methods. Coreflooding results showed that surfactant solutions had higher imbibition and recovered more oil from liquid-rich core compared with water alone. The soaking/flowback production schedule aided by surfactants was able to recover up to 14% of the original oil in place (OOIP), whereas water alone recovered up to 2% of the OOIP. These observations qualitatively agree with wettability- and IFT-alteration measurements. Core wettability shifted from an original oil-wet to a final water-wet state, and surfactants reduced IFT to moderately low values. In addition, surfactants showed adsorption capacity following a Langmuir-type adsorption profile. The results showed that the addition of surfactants to completion fluids and the use of a soaking/flowback production scheme could improve oil recovery by wettability alteration and IFT reduction, maximizing well performance after stimulation. These findings provide an important understanding for designing completion-fluid treatments and flowback schedules for ULRs.

Renewable Surfactants for Biochemical Applications and Nanotechnology

AbstractSurfactants find applications in almost every chemical industry, such as household and industrial cleaning, paper, inks, agrochemicals, and personal care or pharmaceuticals. However, their production and use can have a negative impact on the environment and health. Increasing environmental concerns and the strong interest in renewable resources have led to the development of innovative and environmentally friendly surfactants produced by clean and/or sustainable technologies. The aim of this review is to explore the different types of surfactants and their architectures. Then, it will describe the two categories of renewable surfactants: biosurfactants obtained by fermentation, and bio‐based surfactants containing either a bio‐sourced polar head group or a bio‐sourced hydrophobic tail. Finally, this review will focus on highly specialized applications of surfactants (protein crystallization, transfection, and nanotechnology), which are closely related to the ability of surfactants to organize themselves in supramolecular architectures.

Improved spectrofluorimetric determination of mebendazole, a benzimidazole anthelmintic drug, through complex formation with lanthanum (III); Application to pharmaceutical preparations and human plasma

A, rapid and specific spectrofluorimetric procedure was developed and validated for determination of mebendazole. The reaction of mebendazole with lanthanum (III) ions in aqueous buffered solution (pH 5.5) produced a highly fluorescent stable complex which exhibited an emission at 340 nm (λex 295 nm). Different types of surfactant were examined to enhance the fluorescence of the complex but none of them was effective. Other reaction parameters that affect the formation and stability of the resulting complex were studied and adjusted. The linearity range for the relationship between the fluorescence intensity and the drug concentration was 0.07–0.8 μg mL−1 with a correlation coefficient (r) of 0.9997. The quantitation and detection limits were 0.068 and 0.022 μg mL−1, respectively. The metal was found to react with the drug in the ratio of 2:1 drug to metal with a binding constant of 1.67 × 105. The change in Gibb's free energy for the reaction was −29.8 KJ mol−1, which indicates the high feasibility of the reaction. Some dosage forms and spiked human plasma were analyzed successfully with the developed method with high recovery. The main percentage recovery was in the range of 100.32–100.52% for dosage forms and 94.74–97.31% for spiked plasma. The results of both the reported and proposed methods were statistical compared and the comparison revealed good accuracy and precision of the proposed method.

Adsorption and Photocatalytic Degradation of Anionic and Cationic Surfactants on Nitrogen‐Modified TiO2

AbstractAdsorption and photocatalytic decomposition of anionic and cationic surfactants are presented. Two different types of photocatalysts were studied, commercial TiO2‐P25 (Evonik) with pHpzc = 5.65 and nitrogen‐modified TiO2/N pHpzc = 6.7 (point of zero charge). Two different types of surfactants were used: anionic surfactant NaDBS (sodium dodecylbenzene sulfonate) and cationic surfactant BtCl (benzethonium chloride). Obtained adsorption isotherms of NaDBS and BtCl comply with the conditions of monolayer Langmuir model isotherms. The maximal anionic surfactant adsorption took place at acidic pH and it was higher for TiO2/N (196 mg g−1) than for commercial TiO2‐P25 (140 mg g−1). There was the opposite situation in the case of cationic surfactants, higher adsorption took place at alkaline condition and it was higher for TiO2/N (100 mg g−1) than for commercial TiO2‐P25 (85 mg g−1). Photocatalytic degradation has been found to be more effective in neutral and high than in low pH solutions for both surfactants. It is mainly the difference between charges of the surface of photocatalysts and ionic parts of individual surfactants that determined the effectiveness for each of them.

Mesoscale modeling of emulsification in rotor-stator devices: Part II: A model framework integrating emulsifier adsorption

Precise and rational control of droplet size distribution (DSD) is important in emulsification for target-oriented product design. To develop a complete DSD model, crossing the two mesoscales of two different levels is of great significance, viz., the emulsifier adsorption at interfacial level (Mesoscale 1) and the droplet breakage and coalescence in turbulence in rotor-stator device level (Mesoscale 2). While the first mesoscale can be simulated by coarse-grained molecular dynamic (CGMD), the second has been investigated in computational fluid dynamics and population balance model (CFD-PBM) simulation through the Energy-Minimization Multi-Scale (EMMS) approach in Part I. We then developed a model framework in Part II, coupling CGMD and CFD-PBM simulation through surfactant transport equations in bulk phase and at interface, with source terms taking account of emulsifier adsorption parameters. The parameters including maximal adsorption amount, diffusion coefficient and adsorption/desorption kinetic constants are acquired from CGMD. The coalescence efficiency is then corrected by the interfacial area fraction not occupied by surfactant and fed into the coalescence kernel functions in PBM. Compared to traditional CFD-PBM simulation, the coupled model can greatly improve the simulation of DSD, Sauter mean diameter, median diameter and span for high dispersed phase amount (DPA), and correctly reflect the influence of DPA, surfactant concentration and rotational speed of rotor-stator (RS) devices. While the simulation cases validate and demonstrate the advantage of this new model framework, it is also promising to incorporate different types of surfactant in future.

Selectivity and Reactivity of ZrIV and CeIV Substituted Keggin Type Polyoxometalates Toward Cytochrome c in Surfactant Solutions.

In this paper we investigate the effect of three different types of surfactants, on the hydrolysis of Cytochrome c (Cyt c), a predominantly α helical protein containing a heme group, promoted by [Ce(α PW11O39)2]10- (CeK) and [Zr(α PW11O39)2]10- (ZrK) polyoxometalates. In the presence of SDS, Zw3 12, or CHAPS surfactants, which are commonly used for solubilizing hydrophobic proteins, the specificity of CeK or ZrK toward hydrolysis of Cyt c does not change. However, the hydrolysis rate of Cyt c by CeK was increased in the presence of SDS, but decreased in the presence of CHAPS, and was nearly inhibited in the presence of Zw3 12. The Circular dichroism and Tryptophan fluorescence spectroscopy have shown that the structural changes in Cyt c caused by surfactants are similar to those caused by POMs, hence the same specificity in the absence or presence of surfactants was observed. The results also indicate that for Cyt c hydrolysis to occur, large unfolding of the protein is needed in order to accommodate the POMs. While SDS readily unfolds Cyt c, the protein remains largely folded in the presence of CHAPS and Zw3 12. Addition of POMs to Cyt c solutions in CHAPS results in unfolding of the structure allowing the interaction with POMs to occur and results in protein hydrolysis. Zw3 12, however, locks Cyt c in a conformation that resists unfolding upon addition of POM, and therefore results in nearly complete inhibition of protein hydrolysis.

Enhancement of the imbibition recovery by surfactants in tight oil reservoirs

Hydraulic fracturing technology can significantly increase oil production from tight oil formations, but performance data show that production declines rapidly. In the long term, it is necessary to increase the development efficiency of block matrix, surfactant-aided imbibition is a potential way. The current work aimed to explain comprehensively how surfactants can enhance the imbibition rate. Laboratory experiments were performed to investigate the effects of wettability, interfacial tension (IFT), and relative permeability as the key parameters underlying surfactant solution imbibition. Two different types of surfactants, sodium dodecyl sulfate and polyethylene glycol octylphenol ether, at varied concentrations were tested on reservoir rocks. Experimental results showed that the oil recovery rate increased with increased wettability alteration and IFT and decreased residual oil saturation. A mechanistic simulator developed in previous studies was used to perform parametric analysis after successful laboratory-scale validation. Results were proven by parametric studies. This study, which examined the mechanism and factors influencing surfactant solution imbibition, can improve understanding of surfactant-aided imbibition and surfactant screening.

A systematic evaluation on the performance and mechanism of surfactants as additive of draw solution in forward osmosis

In this study, the performances of six different types of surfactants, each with a series of concentrations around its critical micelle concentration, were systematically tested as additives of draw solution (DS) to improve the performance of DS in forward osmosis. The influence mechanism of surfactants on DS characteristics, membrane fouling and characteristics of ideal surfactants were discussed comprehensively. The six surfactants showed big differences in considering their effects on the characteristics of DS and their performances, which could be explained by the combined effects of thin dense layer formed by surfactant molecules adsorbed on the surface of supporting layer (SL), blocked pores of SL by micelles aggregation, increased viscosity of DS, improved hydrophilicity of membrane SL and ionization of the hydrophilic groups. The nonionic surfactants could significantly reduce the reverse solute flux, accompanied by sharply decreased water flux and heavy membrane fouling. Compared with nonionic surfactants, the anionic surfactants with their Hydrophile-Lipophilic Balance around 10 could significantly reduce the reverse solute flux while with no or low decrease of water flux and reversible membrane fouling. In our work, Sodium dodecyl benzene sulfonate, at 5 mmol/L concentration, had the best performance on the improvement of DS.

Reinforcing Effect of Carbon Nanotubes/Surfactant Dispersions in Portland Cement Pastes

Decoupling the individual effects of multiwalled carbon nanotubes (MWCNTs) and surfactants when used as reinforcement materials in cement-based composites is aimed in this study. Powder MWCNTs were dispersed in deionized water using different types of surfactants as chemical dispersing agents and an ultrasonic tip processor. Cement pastes with carbon nanotubes additions of 0.15% by mass of cement were produced in two steps: first, the MWCNT/surfactant dispersions were combined with the mixing water, and then, cement was added and mixed until a homogeneous paste was obtained. Mechanical properties of the pastes cured at 7 days were measured, and their fracture behavior was characterized using the linear elastic finite element analysis. It was found that the reinforcing effect of MWCNT was masked by the negative effect of surfactants in the cement matrix; nevertheless, nanotubes were capable of increasing both stress and strain capacity of the composite by controlling the crack propagation process at the tip of the crack.

Darifenacin Hydrobromide loaded nanostructured lipid carrier for oral administration

Darifenacin hydrobromide is a selective ?3 receptor antimuscarinic drug and it is used in the management of urinary frequency, urgency, and incontinence in detrusor instability. It slightly soluble in water, undergoes extensive hepatic first-pass metabolism and has short elimination half-life (3–4 hours). Therefore, It has low bioavailability (15.4 % - 18.6 %). Darifenacin hydrobromide loaded NLCs were formulated by emulsification sonication using different ratios of solid lipid to liquid lipid, different types of surfactants, and different concentration of surfactants. Formula sixteen was considered as an optimized formula based on its particle size, PDI, zeta potential and entrapment efficiency. Formula sixteen subjected to further characterization such as DSC, FT – IR, XRD, AFM, and release study. FT-IR and DSC studies showed no interaction between drug and excipients. XRD study showed that drug in amorphous form. AFM study showed discrete lipid nanoparticles with no aggregation. Release study showed burst release in the first hour followed by sustained and controlled release up to 12 hours. The over all study showed the potential of NLC as a carrier for enhancing the bioavailability of darifenacin hydrobromide as compared to the conventional dosage form.
 Key words: Darifenacin hydrobromide, nanostructured lipid carrier, bioavailability.

Separation of oil-in-water emulsions stabilized by different types of surfactants using electrospun fiber membranes

The compositions of oil-in-water emulsions encountered in industrial processes or in the environment vary widely in the nature of surfactants that stabilize them. This variety creates challenges for applications of membrane separation. Electrospun fiber membranes have shown high permeability and improved robustness against fouling in emulsion separation, but the interaction between emulsions and the membrane, and the fouling mechanism, remains unclear. In this paper, electrospun polyamide membranes were challenged by model emulsions of dodecane stabilized by anionic, cationic, non-ionic and zwitterionic surfactants in both dead-end and cross-flow filtration configurations under constant pressure of 2 psi. The membrane was shown to have high oil rejection (92.7 ± 1.5%), sufficient to meet EPA's regulatory limit, when separating emulsions stabilized by anionic surfactant in cross-flow filtration, while maintaining a steady flux of 44.3 ± 2.6 LMH. Analysis of permeate flux and oil rejection revealed that the types of surfactants influenced the membrane fouling in both dead-end and cross-flow systems, but in different ways. Fouling in dead-end filtration was found to be a function of the electrostatic interactions between the oil droplets and the membrane, while fouling in cross-flow filtration was mainly determined by the hydrophilic/hydrophobic interactions due to the adsorption of surfactants at the interfaces. Blocking filtration models are used to corroborate these findings and illustrate the transition between modes of fouling in dead-end filtration. A de-fouling process was found when separating emulsions stabilized by cationic surfactant in dead-end filtration, which was attributed to coalescence of oil droplets at the membrane surface, based on a kinetic model and direct observation. These results indicate that not only membrane-foulant but foulant-foulant interactions can influence the membrane fouling.

Effect of Graphene Flakes Modified by Dispersion in Surfactant Solutions on the Fluorescence Behaviour of Pyridoxine.

The influence of graphene (G) dispersions in different types of surfactants (anionic, non-ionic, and cationic) on the fluorescence of vitamin B6 (pyridoxine) was studied. Scanning electron microscopy (SEM) was used to evaluate the quality of the G dispersions via measuring their flake thickness. The effect of surfactant type and concentration on the fluorescence intensity was analyzed, and fluorescence quenching effects were found for all of the systems. These turn out to be more intense with increasing both surfactant and G concentrations, albeit they do not depend on the G/surfactant weight ratio. For the same G concentration, the magnitude of the quenching follows the order: cationic > non-ionic ≥ anionic. The cationic surfactants, which strongly adsorb onto G via electrostatic attraction, are the most effective dispersing agents and they enable a stronger interaction with the zwitterionic form of the vitamin; the dispersing power improves with increasing the surfactant chain length. The fit of the experimental data to the Stern-Volmer equation suggests either a static or dynamic quenching mechanism for the dispersions in non-ionic surfactants, while those in ionic surfactants show a combined mechanism. The results that were obtained herein have been compared to those that were reported earlier for the quenching of another vitamin, riboflavin, to elucidate how the change in the vitamin structure influences the interactions with G in the surfactant dispersions.

The efficacy of surfactants in stabilizing coating of nano-structured CuO particles onto the surface of cotton fibers and their antimicrobial activity

The efficacy of surfactants in stabilizing CuO-NPs onto the surface of the cotton fibers and their ability to produce homogeneous CuO-coated cotton composite was studied using different types of surfactants. The use of surfactants provides better adhesion of the CuO NPs and consequence, enhanced its coating stability during exploitation. The optical structure and morphology of the coated cotton fabrics were examined by several methods include: X-ray diffraction (XRD), scanning electron microscope (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform spectroscopy (FTIR). The CuO-NPs-coated cotton fabrics have resisted the intensive 10 washing cycles in particular, in presence of SDS (25% loss of CuO) in comparison with TX-100 (66.5% loss of CuO). The CuO-NPs coated cotton materials have also showed an excellent inhibition for the growth of the medically relevant staphylococcus aureus and escherichia coli respectively by 91% and 95% using SDS and HY.

The Stability of Detonation Nanodiamond Hydrosols in the Presence of Salts and Surfactants

The regions of stability and coagulation of hydrosols of oxidized detonation nanodiamonds in the presence of inorganic salts and surfactants of different types have been determined. Concentration Cc of inorganic salts corresponding to the onset of the growth of aggregates in a hydrosol dramatically decreases with an increase in coagulating ion charge z: Cc ~ z−5.3. Anionic and nonionic surfactants stabilize dispersions of nanodiamonds, while additives of cationic and zwitterionic surfactants cause coagulation. The study of the coagulating effect of alkylpyridinium chlorides has shown that the coagulation threshold halves upon elongation of the hydrocarbon chain in a surfactant molecule by a СН2 group.

Morphology and structure of WS2 nanosheets prepared by solvothermal method with surfactants

ABSTRACTIn this work, a modified solvothermal method has been developed to synthesize few layers of tungsten disulfide-nanosheets(WS2-NS). Different types of surfactants were also employed in the modified solvothermal method with respect to the original procedure. As-prepared WS2 samples were characterized by XRD, TEM, and Raman spectrum. The results showed that the obtained WS2-NS were consisted of 1–10 atomic layers. Importantly, the effects of surfactant on the morphology formation of WS2-NS were investigated. A possible growth mechanism is presented to explain the formation of WS2-NS.

Effect of salinity on the IFT between aqueous surfactant solution and crude oil

ABSTRACTThe effect of salts and different surfactants on the equilibrium as well as dynamic interfacial tension (DIFT) between crude oil and water was investigated. Three different types of surfactants with identical hydrophobic chain length C12: Sodium Lauryl Ether Sulphate (SLES), Dodecyl Trimethyl Ammonium Bromide (DTAB), Polyoxyethylene (23) lauryl ether (C12E23) were used in this study. SLES shows better synergism of salt and surfactant mixture amongst the surfactants studied. The order of synergism of salts with the surfactant observed was MgCl2>CaCl2> NaCl. The results obtained from partition coefficient study show that the addition of salts favours the partition of surfactants into the oil phase hence reduce IFT more effectively. DIFT results reveal that, salt accelerates the surfactant migration towards the interface, hence, reducing the t* value.

Comparison on Promotion Effect of Various Types of Surfactants on HCFC-141b Hydrate Induction Time

Cold storage in air conditioning based on refrigerant hydrate is a new-type energy saving technology to reduce initial investment and running cost of air conditioning equipments and improve system stability. Refrigerant hydrate is generated under critical temperature and pressure condition, while surfactant is an effective medium to promote its phase equilibrium. In this paper, in order to research such promotion effect, different type of surfactants with unique mechanism, SDS, Tween80 and Span80, n-BA were selected to compare the respective impact on HCFC141b hydrate induction time based on temperature curve. Experimental results showed that no obvious change had been discovered when no surfactant was added into pure water system, which coincided with phase equilibrium diagram of HCFC141b. All the four kinds of surfactants had realized promotion effect to various degrees. For each hydration system, a large gap existed between the longest and the shortest induction time in 6 groups of parallel experiments, meaning relatively poor system stability. Under the combined effect of Tween80 (2wt%), Span80 (0.1wt%) and n-BA (0.1wt%), average and the shortest induction time was 20.9min and 17.5min respectively, corresponding to the best promotion effect.

The environmental-sensitivity of a fluorescent ZTRS-Cd(ii) complex was applied to discriminate different types of surfactants and determine their CMC values.

We have, for the first time, reported a fluorescent probe (ZTRS-C18-Cd(ii) complex) which discriminated four types of surfactants. This recognition was realized depending on the transformation of ZTRS-Cd2+ binding patterns in different microenvironments formed in various types of surfactants.