Different Kinds Of Surfactants Research Articles

Crystal Facet Control of Nickel–Cobalt Sulfide Nanostructure and Study of Supercapacitor Performance

Supercapacitors require excellent cycling stability and rate capability for electrodes. The NiCo2S4 spinel structure has caught much attention for its high conductivity and high theoretical specific capacity. However, due to the lack of active sites, it has been restricted in supercapacitors. In this research, the NiCo2S4 nano-material with needle, sheet and porous network morphologies were prepared by the addition of different kinds of surfactants via a simple hydrothermal method. At 1[Formula: see text]mA/cm2, capacitance of these NiCo2S4 nanomaterials is measured as 2.09[Formula: see text]F/cm2, 3.22[Formula: see text]F/cm2, and 4.42[Formula: see text]F/cm2, respectively. It was found that the exposure ratio of (111) and (220) crystal facets also has an effect on electrochemical performance, and NiCo2S4 with I[Formula: see text]/I[Formula: see text] of 3:1 showed better performance. Furthermore, NiCo2S4-PN//AC asymmetrical supercapacitor was assembled with NiCo2S4-PN serving as positive electrode and activated carbon (AC) as negative electrode. At a power density of 7.284[Formula: see text]mW/cm2, energy density achieved was 0.625[Formula: see text]mWh/cm2. Additionally, capacitance retention rate remained at 79.6% of initial capacitance after 1500 cycles. These outcomes are of great significance for developing more efficient, stable and reliable transition metal sulfide-based supercapacitors.

Repeated Aqueous Film-Forming Foams Applications: Impacts on Polyfluoroalkyl Substances Retention in Saturated Soil.

Historical practices at firefighter-training areas involved repeated aqueous film-forming foams (AFFFs) applications, resulting in source zones characterized by high concentrations of perfluoroalkyl and polyfluoroalkyl substances (PFAS). Repeated applications of AFFF composed of 14 anionic and 23 zwitterionic perfluoroalkyl substances (PFAS) were conducted on a single one-dimensional saturated soil column to quantify PFAS retention. An electrofluorination-based (3M) Milspec AFFF, which was above the mixture's critical micelle concentration (CMC), was at application strength (3%, v/v). Retention and retardation of PFAS mass increased with each successive AFFF addition, although the PFAS concentration profiles for subsequent applications differed from the initial. Greater degree of mass retention and retardation correlated with longer PFAS carbon-fluorine chain length and charged-headgroup type and as a function of AFFF application number. Anionic PFAS were increasingly retained with each subsequent AFFF application, while zwitterionic PFAS exhibited an alternating pattern of sorption and desorption. Surfactant-surfactant adsorption and competition during repeat AFFF applications that are at concentrations above the CMC resulted in adsorbed PFAS from the first application, changing the nature of the soil surface with preferential sorption of anionic PFAS and release of zwitterionic PFAS due to competitive elution. Applying a polyparameter quantitative structure-property relationship developed to describe sorption of AFFF-derived PFAS to uncontaminated, saturated soil was attempted for our experimental conditions. The model had been derived for data where AFFF is below the apparent CMC and our experimental conditions that included the presence of mixed micelles (aggregates consisting of different kinds of surfactants that exhibit characteristics properties different from micelles composed of a single surfactant) resulted in overall PFAS mass retained by an average of 27.3% ± 2.7% (standard error) above the predicted values. The correlation was significantly improved by adding a "micelle parameter" to account for cases where the applied AFFF was above the apparent CMC. Our results highlight the importance of interactions between the AFFF components that can only be investigated by employing complex PFAS mixtures at concentrations present in actual AFFF at application strength, which are above their apparent CMC. In firefighter-training areas (AFFF source zones), competitive desorption of PFAS may result in downgradient PFAS retention when desorbed PFAS become resorbed to uncontaminated soil.

Experimental Curriculum Reform of Applied Chemistry in Petroleum Colleges and Universities

In order to further improve the comprehensive experimental skills of undergraduates, understand the performance of different surfactants, and understand the working principles and evaluation methods of drainage gas recovery more effectively, a comprehensive experiment of foam draining agents were designed using four different kinds of surfactants. The surface tension, foaming ability and stability were evaluated. The students can further comprehend the investigative background and applicative field of the foam drainage agent as well as deepen the understanding of mechanization of foaming ability and stability through the design of this experiment. This experiment combines chemicals theory and experimental technology, which can improve students’ professional test skills, skills of analysis and problem-solving.

A Comprehensive Experimental Investigation of Additives to Enhance Pool Boiling Heat Transfer of a Non-Azeotropic Mixture.

Adding nanoparticles or surfactants to pure working fluid is a common and effective method to improve the heat transfer performance of pool boiling. The objective of this research is to determine whether additives have the same efficient impact on heat transfer enhancement of the non-azeotropic mixture. In this paper, Ethylene Glycol/Deionized Water (EG/DW) was selected as the representing non-azeotropic mixture, and a comparative experiment was carried out between it and the pure working fluid. In addition, the effects of different concentrations of additives on the pool boiling heat transfer performance under different heat fluxes were experimentally studied, including TiO2 nanoparticles with different particle diameters, different kinds of surfactants, and mixtures of nanofluids and surfactants. The experimental results showed that the nanoparticles deteriorated the heat transfer of the EG/DW solution, while the surfactant enhanced the heat transfer of the solution when the concentration closed to a critical mass fraction (CMC). However, the improvement effect was unsteady with the increase in the heat flux density. The experimental results suggest that the mass transfer resistance of the non-azeotropic mixture is the most important factor in affecting heat transfer enhancement. Solutions with 20 nm TiO2 obtained a steady optimum heat transfer improvement by adding surfactants.

Study on the change law of physical and mechanical properties and wetting mechanism of coal body under the synergistic effect of chelation-adsorption

ABSTRACT A chelating agent dissolves minerals in the coal body through chelation, and a surfactant increases the permeability of the solution by reducing surface tension of the solution. The chelating agent and the surfactant are compounded into the compound wetting agent, and the wetting effect of the coal body can be significantly improved by using different infiltration mechanisms. By measuring the surface tension of different kinds of surfactants and their contact angles with the coal body, the surfactant with the best effect was selected and combined with the chelating agent. The change law of moisture content and compressive strength of the coal body and other mechanical properties were determined after soaking in the solution. The results showed that surface tension of different surfactants SAS, BS-12, and JFCS and contact angle with the coal body all decrease with the increase of the mass concentration and the effect of JFCS is the best under the same concentration. When the concentration of surfactant increases to 0.05%, the surface tension and contact angle with the coal body will no longer decrease significantly. By soaking coal with the compound wetting agent consisting of 0.05% surfactants JFCS and 0.4% chelating agent, the water content of the coal body is 21%, which is 2.0 times that of the raw coal. The uniaxial compressive strength, elastic modulus, and impact energy index of the coal body are 6.5 MP, 547 MPa, and 1.1, respectively, which are 63%, 22%, and 91% lower than those of the raw coal, respectively. The dynamic failure time is 12271 ms, which is 17 times that of the raw coal. Through the chelation and wetting effect of the chelating agent and the adsorption and wetting effect of the surfactant, the compound wetting agent can promote seepage and migration of water in the coal body under the chelating-adsorption synergistic effect and improve the effectiveness of water injection in the deep coal seam.

Solubilization of surfactant stabilized gold nanoparticles in oil – in – water and water – in – oil microemulsions

W/O and O/W microemulsions were used for determining the solubilization capacity of surfactant stabilized Au nanoparticles (NPs) as metallic nano-pollutants. Tween 80 (emulsifier), hexane/dodecanethiol (oil), and isopropyl alcohol (cosurfactant) were used to prepare microemulsions along with aqueous Au NPs. Different kinds of surfactants were used to produce surfactant stabilized Au NPs. Solubilization studies were carried out by measuring the UV–visible spectra of Au NPs on the basis of their surface plasmon resonance (SPR), dynamic light scattering, and fluorescence measurements to determine the solubilization capacity of aqueous Au NPs. Results indicated that solubilization capacity showed little dependence on the nature of surfactant used for preparing surfactant stabilized Au NPs rather it depended more on the amount of Tween 80 in the preparation of microemulsion. Higher amount of Tween 80 provided greater solubilization capacity of microemulsion to solubilize Au NPs. Stability of the microemulsion was determined from the fluorescence measurements by using fluorescence active surfactant and found that the micromeulsion was stable up to 55 °C for solubilization study. The findings are expected to design microemulsion systems suitable for solubilizing metal industrial effluents.

The Impacts of Nanoparticle Concentration and Surfactant Type on Thermal Performance of A Thermosyphon Heat Pipe Working With Bauxite Nanofluid

ABSTRACT Heat pipes are one of the most preferred equipment because they have a variety of superior specifications. In this paper, the improvement of heat transfer properties of a thermosyphon heat pipe that was filled with bauxite nanofluid was experimentally investigated for different nanoparticle concentrations (1%, 2%, and 4%) and surfactant types (Triton X-100 and Sodium Dodecyl Benzene Sulfonate). Bauxite nanoparticles at different concentrations were utilized for the preparation of nanofluid suspensions. Different kinds of surfactants were also doped into the prepared nanofluid suspensions to show off how a surfactant affects the thermophysical properties of the nanofluid. The experiments were done under several heating powers and various mass flow rates of the cooling water circulating on the evaporator section. Temperature distributions both upon the evaporator and the condenser sections were recorded via 8 different K type thermocouples. Cooling water inlet and exit temperatures were also recorded and utilized for theoretical calculations. For doing an experimental comparison, thermal efficiency and resistance of the thermosyphon heat pipe were determined both for distilled water and prepared nanofluid suspensions. Moreover, contact angle-wettability analysis was carried out to determine how nanoparticles affect the surface tension. The encountered problems during the tests were addressed and discussed. The obtained experimental data illustrated that the thermosyphon heat pipe efficiency was increased by up to 20.9% with the usage of a 2% (mass) concentration of bauxite nanofluid and an anionic surfactant. The maximum enhancement in heat pipe’s thermal resistance was found as 24.3%, through bauxite nanofluid usage.

Impact of Surfactants on Polymer Maintained Nifedipine Supersaturation in Aqueous Solution.

To study the impact of different surfactants on the supersaturation of nifedipine stabilized with HPMC and PVP-VA. Different kinds of surfactants, including one cationic surfactant, two anionic surfactants, and three nonionic surfactants, were used to evaluate their impacts on the supersaturation of nifedipine stabilized with HPMC and PVP-VA. Polymer-surfactant interaction was studied by nuclear magnetic resonance (NMR) and fluorescent method. Solubility of nifedipine in solutions containing different amounts of polymers and surfactants was measured. Drug-polymer affinity was evaluated by measuring the percentage of polymer coprecipitated together with the drug from supersaturated solutions. Different polymer-surfactant combinations had different impacts on the supersaturation of nifedipine. Some combinations, such as PVP-VA/SLS and PVP-VA/NaTC under higher surfactant concentrations, showed improved drug supersaturation, due to increased drug solubility or polymer-surfactant synergy; while other combinations, such as HPMC/SLS and HPMC/Tween 20 under lower surfactant concentrations, showed reduced drug supersaturation, which could result from competitive surfactant-polymer or drug-surfactant interaction that disrupted pre-existent drug-polymer interaction. The ultimate impacts of various surfactants on polymer stabilized nifedipine supersaturation could be attributed to the interplay between different factors, including solubility enhancement of the drug, drug-polymer-surfactant interactions, and polymer-surfactant synergy.

Determining the Critical Micelle Concentration of Surfactants by a Simple and Fast Titration Method.

Critical micelle concentration (CMC) is a crucial parameter of widely used surfactants, and many methods have been developed for CMC determination. However, the current methods for CMC determination, such as conductive, surface tension, and fluorometric methods, are tedious and time- and sample-consuming because a series of samples with different concentrations of surfactants need to be prepared and measured. Although an economical, simple, and fast titration method for CMC determination (only one sample and several minutes are needed) was reported using changes in the color/fluorescence of ionic organic dyes, it has not been used in practical CMC determination owing to the disadvantages of these dyes: very narrow application range (only suitable for cationic or anionic surfactants) and difficult to identify titration end point, especially using different concentrations (10-300 μM) for the same kind surfactants. Here a C6-unsubstituted tetrahydropyrimidine (THP-T1) was found to possess unique and excellent characteristics in titrated surfactant solutions: above CMC, preferring to dissolve in micelles and showing no emission, and not until near/at CMC, being released from micelles and instantly forming aggregates with strong fluorescence. The fluorescence-turn-on change at CMC (titration end point) is so sensitive that it can be clearly observed without comparison of blank and control of dye concentration, and the concentration (c'THP) of THP-T1 in titrated solution at CMC is only about 1 μM for zwitterionic surfactants and 2.5 μM for other kinds of surfactants. The CMC values determined by the THP-T1-based titration method are almost the same as those determined by the fluorometric method using THP-T1 as probe. THP-T1 overcomes the disadvantages of reported dyes for CMC titration and realizes the economical, simple and fast CMC titration of different kinds of surfactants for the first time.

Extended Surfactants Including an Alkoxylated Central Part Intermediate Producing a Gradual Polarity Transition—A Review of the Properties Used in Applications Such as Enhanced Oil Recovery and Polar Oil Solubilization in Microemulsions

AbstractThe research published in the past half century indicates that surfactant interfacial performance in producing low tension or high solubilization with polar oils is not generally attained with pure conventional species exhibiting well‐defined polar and nonpolar parts. The improvement trends reached with surfactant mixtures as well as the introduction of additives like cosurfactants and linkers lead to the introduction of the so‐called extended surfactants, whose structure includes an intermediate polarity spacer between the hydrophilic head and the lipophilic tail. Recent investigations on different kinds of surfactants in a variety of applications—such as detergency, cosmetics, enhanced oil recovery or crude demulsifying, and vegetable oil extraction—indicate that these extended surfactants are likely to be particularly performing with oils containing polar groups, such as triacylglycerols and asphaltenic crudes. Possible applications of extended surfactants in enhanced oil recovery, crude emulsion breaking, detergency and cleaning, medicine and cosmetics vehicles, and natural oil extraction as well as some other cases are quickly reviewed.

Relative permeability measurement in carbonate rocks, the effects of conventional surfactants vs. Ionic liquid-based surfactants

In the present study, the effect of two different kinds of surfactants namely conventional (Sodium dodecyl benzene sulfonate (SDBS)) and ionic liquid (IL)-based surfactants are investigated on the tertiary oil recovery using relative permeability concept. In this way, besides the Amott wettability index measurement, unsteady state core flooding tests are performed to not only find the effect of surfactant injection on tertiary oil recovery, but also to investigate their effects on relative permeability of carbonate rocks. In addition, for more reliable conclusions regarding the possible mechanisms, interfacial tension (IFT), compatibility and emulsification tests are carried out as a function of concentration. According to the results obtained through the core flooding experiments, it can be concluded that the injection of SDBS which substantially reduces the IFT value leads to higher tertiary oil recovery (26% based on original oil in place (OOIP)) although the ILs revealed more compatibility at the presence of harsh salinity conditions at any examined IL concentration in this study. Finally, the results obtained by plotting the relative permeability data and mining into the cross points one can conclude that in the case of using ILs, the active mechanisms during the tertiary oil recovery is dominantly related to wettability alteration mechanism while in the case of SDBS, the IFT reduction is the active mechanism.

Cytotoxicity of lecithin-based nanoemulsions on human skin cells and ex vivo skin permeation: Comparison to conventional surfactant types

As constituents of cellular membranes, lecithins feature high biocompatibility and great emulsifying properties due to their amphiphilicity. Additionally, there are expectations that these naturally occurring emulsifying agents can replace other skin damaging emulsifiers like sodium dodecyl sulfate or sodium laureth sulfate. However, cytotoxicity data of lecithin-based formulations on primary human skin cells are scarce. Thus, we developed nanoemulsions with different kinds of surfactants (amphoteric, anionic and non-ionic), studied the skin permeation of a model drug from this formulations employing Franz-type diffusion cells and monitored their cytotoxicity potential on primary human keratinocytes and fibroblasts using a cell proliferation assay. The skin diffusion studies demonstrated that the amphoteric lecithin-based emulsifiers were superior to non-ionic surfactants in terms of skin permeation, but inferior to anionic emulsifiers. Further, we found that the nanoemulsions containing the amphoteric lecithins as emulsifying agents lead to significantly higher viability rates of both epidermal keratinocytes and dermal fibroblasts than the investigated anionic and non-ionic surfactants. This renders them a promising alternative to conventional emulsifiers used in daily products.

Synthesis, growth mechanism and photocatalytic property of CdS with different kinds of surfactants

CdS is a well-known visible-light-sensitive semiconductor and has been widely used in photocatalysis. In order to improve the photocatalytic of CdS, CdS structures with different kinds of surfactants were synthesized by hydrothermal method.

Effect of Selected Surfactants on Kinetics of Meloxicam Release from Rectal Suppositories

The use of surfactants in suppository formulations has been suggested to improve the bioavailability of poorly soluble drugs. In the present study, different kinds of surfactants were investigated to understand their influence on meloxicam release from suppositories formulated with a lipophilic base. Tween 80, Span 80, soy lecithin and sodium lauryl sulfate were the surfactants used in this study. The suppositories were prepared in a recipe mixer using Witepsol H15 and cacao oleum as a base. The suppositories with and without the addition of surfactants were examined using physicochemical tests according to the Polish Pharmacopeia, the uniformity of mass of single-dose preparation test, the content uniformity test, the softening time determination of lipophilic suppositories test, the disintegration test of suppositories, and the dissolution test. All the prepared formulations complied with the pharmacopeia requirements. The prepared suppositories were evaluated for in vitro drug release immediately after preparation and after storage. The results revealed that the bioavailability of meloxicam was to 36 % from suppositories formulated with Witepsol H15 and 23.4 % those formulated with cacao oleum. Addition of surfactants to the suppository base significantly influenced both the amount and rate of meloxicam released into the phosphate buffer. The highest release rate of meloxicam was observed with the formulation prepared on a Witepsol H15 base with Tween 80. Present results have confirmed the possibility of using surfactants in suppository formulations, in order to improve the dissolution rate of meloxicam in vitro. As a consequence, a faster onset of pharmacodynamic action and better therapeutic effects of the medication can be obtained.

Versatile preparation of vesicle from amphiphilic bottlebrush block copolymers

Polymeric vesicles show vast potential in drug delivery for the treatments of various diseases. In this work, we report here an advanced polymeric vesicle formed by amphiphilic bottlebrush block copolymers (BBCPs), which have a large size and can resist different kinds of surfactants in a degree. The amphiphilic BBCPs with controlled molecular weights and narrow molecular weight distributions were synthesized by ring-opening metathesis polymerization of norbornyl-poly (ethylene glycol) (NPEG) and norbornyl-trithiocarbonates (NTTA) followed by reversible addition-fragmentation chain transfer (RAFT) with styrene. GPC and 1HNMR were used to characterize BBCPs. Turbidity measurements, transmission electron microscopy, and scanning electron microscopy were used to explore the morphologies of the aggregation. Depending on the content of water added, many intermediate structures like compound vesicles and sphere could be found. After lyophilization, the BBCP vesicles happended a fusion and can retain vesicle morphology and show some stability in the presence of sodium dodecyl sulfate (SDS), hexadecyl trimethyl ammonium bromide (CTAB), Brij 78P and sodium chloride. This work serves a promising way to construct stable vesicles with BBCPs for biomedical applications.

Morphologies Tuning of Polypyrrole and Thermoelectric Properties of Polypyrrole Nanowire/Graphene Composites.

Polypyrrole (PPy) with different morphologies (e.g., particles, nanotubes, and nanowires) were successfully prepared by adding or without adding different kinds of surfactants through a chemical oxidative polymerization method, respectively. The results show that the morphologies of PPy can be effectively controlled and have a significantly effects on their thermoelectric properties. The PPy nanowires exhibit the highest electrical conductivity and Seebeck coefficient among the various PPy morphologies, such as particles, nanotubes, and nanowires, so PPy nanowires were chosen to prepare PPy nanowire/graphene thermoelectric composites via a soft template polymerization method using cetyltrimethyl ammonium bromide as the template. Both electrical conductivity and Seebeck coefficient of the PPy nanowire/graphene composites increased as the content of graphene increases from 0 to 20 wt %, and as the measured temperature increases from 300 K to 380 K, which leds to the same trend for the power factor. A highest power factor of 1.01 μWm−1K−2 at ~380 K was obtained for the PPy nanowire/graphene composites with 20 wt % PPy nanowire, which is about 3.3 times higher than that of the pure PPy nanowire.

Two-step washing with commercial vegetable washing solutions, and electrolyzed oxidizing microbubbles water to decontaminate sweet basil and Thai mint: A case study

A study was conducted on pre-washing vegetables with four different kinds of surfactant in the washing solution, followed by an acidic electrolyzed oxidizing microbubbles water (AEO-MB) to compare their efficacy on the decontamination of E. coli and S. Typhimurium on sweet basil and Thai mint. Three commercial surfactants (0.1% v/v) and Tween 80® were applied in pre-washing with a constant rate of shaking at 60 rpm for 3 min, then washed with 40 mg/L of AEO, oxidation reduction potential (ORP) 1130–1180 mV and pH 2.8–3.1, under the continuous generation of MB for 5 min. All surfactants showed no antimicrobial activity but greater decontamination (99.0–99.9%) was observed when two-step washing was applied. Wash water with AEO indicated the absence of microorganisms thus helping to prevent cross-contamination. Our study revealed that pre-washing helped to improve the washing efficacy and to enhance the food safety of sweet basil and Thai mint and the treatment may be suitable for application with household or commercial ready-to-eat produce.

The oil displacement effect evaluation of Different Displacing systems

During the chemical flooding, the surfactant and the alkali play an emulsifying role. The emulsification can not only improve the displacement efficiency, but also expand the swept volume by the mechanism of emulsifying trapping. We select some chemical flooding systems including different kinds of surfactants, alkali/alkali-free and different emulsion degrees to make the comparative experiment and draw the conclusion that it is an effective way to enhance the recovery by increasing the emulsion stability without having to pursue the ultra-low interfacial tension.

In situ microcalorimetric investigation on effects of surfactants on cluster-shaped Ni-doped Fe3O4 formation

In situ calorimetric technology was firstly employed to study the effects of surfactants on the materials formation. In the present study, different kinds of surfactants were selected as additives during cluster-shaped Ni-doped Fe3O4 synthesis. Experimental results indicate that the surfactants reduced the particle size and changed the cationic distribution, compositions and magnetic properties of the as-synthesized materials. The microcalorimetric results demonstrate that the sample formation was endothermal and divided into five processes based on the heat-flow versus time curves. No significant effects of the surfactants on these processes were found. However, the surfactants addition affected the heat flow and the temperatures for peaks in these curves. The surfactant adsorption on the crystal facet and nuclei of the sample, and the interactions among surfactants and ions contained in the system may be mainly the reason for these effects. These results demonstrate different actions of surfactants and ligands on materials formation.

The preparation of calcium pimelate modified OMMT from natural Ca-montmorillonite and its application as β-nucleating agent for polypropylene

Ca-montmorillonite (Ca-MMT) was first modified with different amount of two different kinds of surfactants to obtain organo-montmorillonites (OMMTs) directly via ion exchange between Ca2+ and alkyl ammonium cations. Then remained Ca2+ in OMMTs was reacted with pimelic acid (HA) to obtain CaHA-OMMTs. PP/CaHA-OMMT composites were prepared. Results of FT-IR demonstrate the existence of long-chain alkyl in OMMTs, and CaHA in CaHA-OMMTs. The reaction between HA and OMMT could lead to an increase in d-spacing value of clay. CaHA-OMMTs with high CaHA contents and obviously increased d-spacing values were obtained. Results of WAXD and TEM show exfoliated clay platelets in PP/CaHA-OMMT composites. The obviously increased Tc, and the high β-phase content in PP/CaHA-OMMT composites demonstrate the high β-nucleation efficiency of CaHA-OMMTs. Composites with higher content of β-phase epitaxial crystallized on exfoliated clay platelets display largely improved impact strength.