Surfactant Type Research Articles

Tailoring microstructure and properties of porous mullite-based ceramics via sol-gel impregnation

Nanotechnology has been introduced into the refractory industry decades ago. However, there are still some peculiarities that hinder its routine application. Poor mechanical strength is one of them. Here we present the fabrication technique for mullite porous ceramics using a calcium-free colloidal binder system followed by secondary sol-gel impregnation intended for fabrication of large up-scaled monoliths. The primary foam was prepared via direct foaming of slurry containing colloidal silica, gelling agents, surfactant, silica fume, and different types of alumina. The foam mixture was cast, de-molded and dried using a cascade drying procedure. The investigation of mullitization that occurred during the high-temperature treatment was studied by XRD and TG-DTA analysis. The optimized sintering curve was then applied to obtain the highest mechanical properties. The resulting foam (with open porosity, volume density about 900 kg/m3 and mechanical strength about 10 MPa) was further processed by the impregnation step. The applied silica or combined silica/aluminum sol and unreacted alumina underwent secondary mullitization during following high-temperature treatment, which significantly enhanced the mechanical strength (up to 18 MPa). The secondary mullitization process was also investigated by HT-XRD and TG-DTA analysis. Foam microstructure was observed by an electron scanning microscope. Thermal conductivity of as-prepared ceramics foams varied from 0.3 to 0.4 W/m·K. The foam wall porosity evolution was studied by mercury intrusion porosimeter and estimated from image analysis.

Flow pattern and pressure loss of foam flow in horizontal pipes: Role of surfactant type and dynamic surface tension

In this work, the flow patterns and pressure losses of 12 kinds of gas–liquid systems (two different surfactants were selected, and their concentrations were changed in an aqueous solution, which served as the test liquid) in horizontal pipes were studied. To explore the potential mechanisms influencing flow patterns, the equilibrium and dynamic surface tensions of surfactant solutions were surveyed, and the aggregate morphologies of surfactants were observed by using cryo-TEM. Based on the experimental findings, a generalized flow pattern map was proposed. Furthermore, the relationship between the pressure loss and the flow pattern of the foam flow was investigated. The results revealed two types of foam flow: full-foaming flow (FFO) and foam flow containing liquid (FCL). Each type of flow had three subflow patterns. The formation of different flow patterns is closely related to the ability of surfactant molecules to adsorb on bubbles and reduce surface tension in a short period, which is affected by aggregates and their structures. The product of the Weber and Bond numbers was determined to be the appropriate combination of non-dimensional numbers for the proposed generalised flow pattern map. Moreover, above a critical Bond number of the gas–liquid system, FFO cannot be formed. Finally, the flow pattern can be effectively separated according to pressure drop data.

Surface activity, foamability, and foam stability of binary mixed systems based on siloxane-based Gemini and hydrocarbon surfactants

Aiming to explore the potential of siloxane-based Gemini surfactants in the development of environmentally friendly foam extinguishing agent to address the pollution caused by traditional fluorinated ones. A crucial step is to study the performance of binary mixed systems of siloxane-based Gemini and hydrocarbon surfactants in terms of surface activity, foamability, and foam stability. In this study, binary mixed systems of two types of siloxane-based Gemini surfactants and one siloxane surfactant with four different hydrocarbon surfactants are prepared. Parameters such as surface tension, foam height, drainage time, and coarsening rate are tested. The results show that the siloxane-based Gemini surfactant HY-4000 with double silane chains could effectively reduce the surface tension of hydrocarbon surfactants. In addition, the two types of Gemini surfactants performed better in enhancing the foamability of hydrocarbon surfactants. The siloxane OFX0193 even inhibits the foaming of cationic hydrocarbon surfactant CATC. Besides the HY-4000/APG0180 mixed system, the binary mixed systems of three silicone surfactants with AOS and APG0180 exhibit better foam stability, particularly the systems containing TEGO4100. For the coarsening process of foam bubbles, we develop a predictive model based on previous studies, where the relationship between bubble area and time follows a power function law. The findings of this study could provide guidance for the development of green foam extinguishing agent with siloxane-based Gemini and hydrocarbon surfactants as core components.

Effect of surfactant's charge properties on behavior, physiology, and biochemistry and the release of microcystins of Microcystis aeruginosa

Surfactant pollution is escalatitheng in eutrophic waters, but the effect of surfactant charge properties on the physiological and biochemical properties of toxin-producing microalgae remains inadequately explored. To address this gap, this study explores the effects and mechanisms of three common surfactants―cetyltrimethylammonium bromide (CTAB, cationic), sodium dodecyl sulfate (SDS, anionic), and Triton X-100 (nonionic)―found in surface waters, on the agglomeration behavior, physiological indicators, and Microcystin-LR (MC-LR) release of Microcystis aeruginosa (M. aeruginosa) by using UV–visible spectroscope, Malvern Zetasizer, fluorescence spectrometer, etc. Results suggest that charge properties significantly affect cyanobacterial aggregation and cellular metabolism. The CTAB-treated group demonstrates a ∼5.74 and ∼9.74 times higher aggregation effect compared to Triton X-100 and SDS (300 mg/L for 180 min) due to strong electrostatic attraction. Triton X-100 outperforms CTAB and SDS in polysaccharide extraction, attributed to its higher water solubility and lower critical micelle concentration. CTAB stimulates cyanobacteria to secrete proteins, xanthohumic acid, and humic acids to maintain normal physiological cells. Additionally, the results of SEM and ion content showed that CTAB damages the cell membrane, resulting in a ∼90% increase in the release of intracellular MC-LR without cell disintegration. Ionic analyses confirm that all three surfactants alter cell membrane permeability and disrupt ionic metabolic pathways in microalgae. This study highlights the relationship between the surface charge properties of typical surfactants and the dispersion/agglomeration behavior of cyanobacteria. It provides insights into the impact mechanism of exogenous surfactants on toxic algae production in eutrophic water bodies, offering theoretical references for managing surfactant pollution and treating algae blooms.

Mitigating strategy and mechanism of cement slurry contamination caused by oil-based mud: Macro-micro experiments, molecular dynamics simulation and dissipative particle dynamics simulation

During the cementing process, the oil-well cement (OWC) inevitably comes into contact with oil-based mud (OBM), which contaminates the OWC due to the incompatibility between OBM and the OWC. As a solution, hydrophilic surfactants can reduce interfacial tension and enhance the wetting compatibility of oil and water. Therefore, adding surfactants to the OWC is expected to alleviate contamination caused by OBM. In this study, a new strategy was proposed to combine non-ionic surfactants and anionic surfactants to form a composite surfactant (OP-S2), which overcomes the defect that excessive use of anionic surfactants deteriorates the performance of the OWC—showing great potential in adjusting the compatibility between OBM and the OWC and reducing cement contamination. The mechanism of contamination alleviation during the cementing process was elucidated by comparing the anticontamination properties of a single non-ionic surfactant (OP-S1) and OP-S2. In addition, molecular dynamics (MD) and dissipative particle dynamics (DPD) simulations were used to verify the mechanism of different types of surfactants in removing contamination further, providing theoretical guidance for future research on anti-contamination agents.

Solubilization of polycyclic aromatic compounds into supralong-chain surfactants with double quaternary ammonium micelles

The dissolution of poorly water-soluble compounds in micelles via hydrophobic interactions is termed solubilization. The solubilization of polycyclic aromatic compounds, namely, naphthalene, anthracene, and pyrene, was studied using supralong-chain surfactants with two consecutive cationic hydrophilic groups [CnH2n+1N+(CH3)2-(CH2)2-N+(CH3)3 2Br-: Cn-2Am (n = 18, 20, and 22)] and typical cationic surfactants [CnH2n+1N+(CH3)3 Br-: Cn-Am (n = 12, 14, and 16)]. Long alkyl chains in hydrophobic surfactants are advantageous for forming a large micellar core. The maximum quantity of solubilized polycyclic aromatic compounds increased as the alkyl chain length of the surfactant increased. Therefore, the molar solubilization ratio (MSR), which represents the solubilization ability of the surfactant, was maximized when the alkyl chain length was C22-2Am. Similarly, the Gibbs free energy (ΔG0) associated with the solubilization of polycyclic aromatic compounds was also lowest for C22-2Am. Surfactants with long alkyl chains functioned as excellent solubilizers. The solubilization sites of the polycyclic aromatic compounds were determined using two-dimensional NMR and small-angle X-ray scattering (SAXS) measurements. As the molecular size of the polycyclic aromatic compounds increased, the solubilization positions in the micelles shifted from the palisade layer to the vicinity of the hydrophilic groups. Extension of the alkyl chain length of the surfactant resulted in an increase in the palisade region of the micelles, which was advantageous for solubilization.

Surfactants produced from carbohydrate derivatives: Part 2. A review on the value chain, synthesis, and the potential role of artificial intelligence within the biorefinery concept

AbstractThis comprehensive and critical review explores the synthesis and applications of carbohydrate‐based surfactants within the biorefinery concept, focusing on biobased sugar‐head molecules suitable for use across several manufacturing sectors, including cosmetics, pharmaceuticals, household products, detergents, and foods. The main focus relies on sustainable alternatives to conventional surfactants, which could reduce the final manufacturing carbon footprint of several industrial feedstocks and products. A thorough analysis of raw materials, highlighting the significance of feedstock sources, and the current biobased surfactants and rhamnolipid biosurfactants production trends, is presented. Key organic reactions for the production of sorbitan esters, sucrose esters, alkyl polyglycosides, and fatty acid glucamines, such as glycosidation, acylation, and etherification, as well as the production of rhamnolipids through fermentation are described. Given the scarce literature on the characterization of these surfactant types within the hydrophilic–lipophilic deviation (HLD) framework, the surfactant contribution parameter (SCP) in the HLD equation for sugar‐head surfactants is critically assessed. The economic landscape is also discussed, noting the significant growth in the biobased surfactants and biosurfactant market, driven by environmental awareness and regulatory changes, with projections indicating a substantial market increase in the forthcoming years. Finally, the promising potential of generative artificial intelligence (AI) in developing customized surfactant molecules, with optimized properties for targeted applications, is emphasized as a promising avenue for future research.

Switchability and synergistic effect of a CO2-responsive surfactant with co-surfactants at an O/W interface: A molecular insight

CO2-responsive surfactants are a promising technology with potential applications in various fields. Therefore, the design of their formulations must be carefully considered to ensure their effectiveness in each specific application. Herein, we employed molecular dynamics simulations to investigate an oil/water (O/W) interface stabilized by a surfactant mixture containing a CO2-responsive cationic primary surfactant and another co-surfactant. It has been discovered that formulating the CO2-responsive cationic surfactant with a typical anionic surfactant (sodium dodecyl sulfate, SDS) can lead to a distinct CO2-responsive mechanism of the surfactant mixture. To compare, the CO2-responsive mechanism remains unchanged if the CO2-responsive cationic surfactant is formulated with a typical cationic surfactant (dodecyl trimethylammonium bromide, DTAB). A nonionic co-surfactant can enhance the interface activity of the surfactant mixture but the synergistic effect is not strong enough to lead to a different CO2-responsive mechanism. The distinct phase behavior between two surfactant mixtures suggests that the CO2-responsive mechanism is dominated by the type of surfactants formulated with the CO2-switchable surfactant.

Addressing the interaction of stem bromelain with different anionic surfactants, below, at and above the critical micelle concentration (cmc) in phosphate buffer at pH 7: Physicochemical, spectroscopic, & molecular docking study

The structural stability and therapeutic activity of Stem Bromelain (BM) have been explored by unravelling the interaction of stem BM in presence of two different types of anionic surfactants namely, bile salts, NaC and NaDC and the conventional anionic surfactants, SDDS and SDBS, below, at and above the critical micelle concentration (cmc) in aqueous phosphate buffer of pH 7. Different physicochemical parameters like, surface excess (Γcmc), minimum area of surfactants at air water interface (Amin) etc. are calculated from tensiometry both in absence and presence of BM. Several inflection points (C1, C2 and C3) have been found in tensiometry profile of surfactants in presence of BM due to the conformational change of BM assisted by surfactants. Similar observation also found in isothermal titration calorimetry (ITC) profiles where the enthalpy of micellization (ΔH0obs) of surfactants in absence and presence of BM have calculated. Further, steady state absorption and fluorescence spectra monitoring the tryptophan (Trp) emission of free BM and in presence of all the surfactants at three different temperatures (288.15 K, 298.15 K, and 308.15 K) reveal the nature of fluorescence quenching of BM in presence of bile salts/surfactants. Time resolved fluorescence studies at room temperature also support to determine the several quenching parameters. The binding constant (Kb) of BM with all the surfactants and free energy of binding (∆G0 of bile salts/surfactants with BM at different temperatures have been calculated exploiting steady state fluorescence technique. It is observed that, the binding of NaC with BM is greater as compared to other surfactants while Stern-Volmer quenching constant (KSV) is found greater in presence of SDBS as compared with others which supports the surface tension and ITC data with the fact that surface activity of surfactant(s) is decreasing with the binding of the surfactants at the core or binding pocket of BM. Circular Dichroism (CD) study shows the stability of secondary structure of BM in presence of NaC and NaDC below C3, while BM lost its structural stability even at very low surfactant concentration of SDDS and SDBS which also supports the more involvement of bile salts in binding rather than surfactants. The molecular docking studies have also been substantiated for better understanding the several experimental investigations interaction of BM with the bile salts/surfactants.

Pressure Changes Across a Membrane Formed by Coacervation of Oppositely Charged Polymer-Surfactant Systems.

We investigate the mass transfer and membrane growth processes during capsule formation by the interaction of the biopolymer xanthan gum with CnTAB surfactants. When a drop of xanthan gum polymer solution is added to the surfactant solution, a membrane is formed by coacervation. It encapsulates the polymer drop in the surfactant solution. The underlying mechanisms and dynamic processes during capsule formation are not yet understood in detail. Therefore, we characterized the polymer-surfactant complex formation during coacervation by measuring the surface tension and surface elasticity at the solution-air interface for different surfactant chain lengths and concentrations. The adsorption behavior of the mixed polymer-surfactant system at the solution-air interface supports the understanding of observed trends during the capsule formation. We further measured the change in capsule pressure over time and simultaneously imaged the membrane growth via confocal microscopy. The cross-linking and shrinkage during the membrane formation by coacervation leads to an increasing tensile stress in the elastic membrane, resulting in a rapid pressure rise. Afterward, the pressure gradually decreases and the capsule shrinks as water diffuses out. This is not only due to the initial capsule overpressure but also due to osmosis caused by the higher ionic strength of the surfactant solution outside the capsule compared to the polymer solution inside the capsule. The influence of polymer concentration and surfactant type and concentration on the pressure changes and the membrane structure are studied in this work, providing detailed insights into the dynamic membrane formation process by coacervation. This knowledge can be used to produce capsules with tailored membrane properties and to develop a suitable encapsulation protocol in technological applications. The obtained insights into the mass transfer of water across the capsule membrane are important for future usage in separation techniques and the food industry and allow us to better predict the capsule time stability.

Influence of Different Types of Surfactants on the Flotation of Natural Quartz by Dodecylamine.

The synergistic effect among flotation agents is why combined flotation agents exhibit superior performance compared to single flotation agents. This research investigates the influence of three surfactants with different charges of polar groups, sodium dodecyl sulfate (SDS), cetyltrimethylammonium bromide (CTAB), and octanol, combined with dodecylamine (DDA), on quartz flotation. Through the implementation of flotation tests, bubble-particle adhesion induction time testing, gas-liquid two-phase foam properties testing, and surface tension testing, it is revealed that substituting part of the DDA with these surfactants can either enhance or at least maintain the quartz recovery, affect the adhesion induction time, reduce the surface tension of the flotation system, and change the foaming performance and foam stability, depending on their mole ratio in the combined collector. Compared to DDA alone, combining CTAB or OCT with DDA can significantly increase quartz recovery, while SDS with DDA only yields an approximate recovery. Combining SDS or OCT with DDA can reduce the foam stability, while CTAB with DDA enhances the foam stability. The effect of the combination of surfactants and DDA on the adhesion induction time of quartz grains of different sizes with bubbles is the same; furthermore, there is a negative correlation between the adhesion induction time and the recovery, while the foaming properties and stability of foam are positively correlated with the recovery.

Experimental and model research on judging liquid accumulation in pipelines under the action of surfactant

Foam drainage gas extraction is applied in various natural gas extraction scenarios, such as water-bearing gas wells, gas fields with high water content, and wet natural gas pipeline transport, with the goal of enhancing extraction efficiency and lowering production costs. A common issue in foam-carrying liquid gas wells and wet natural gas pipelines is the large errors observed in the prediction model for liquid accumulation onset, derived using ellipsoidal droplets. Additionally, this model is only applicable to a single surfactant type and concentration. To investigate the effects of different types and concentrations of surfactants on the onset of liquid accumulation. This paper re-establishes the critical foam-carrying flow rate model for spherical cap-shaped foam droplets using Newton's laws of motion, through an analysis of their motion state within the air core. Through the critical foam-carrying flow rate test experiments and foam droplet deformation test experiments to obtain critical foam-carrying flow rate model in the surface tension, foam density, Weber number, drag coefficient and other parameters of the change rule and calculation method. The model's validity was further confirmed using field-measured production data from foam-carrying liquid gas wells, demonstrating accurate validation results. Compared to the previous model, this new model treats foam droplets as spherical cap-shape and introduces a dimensionless scaling factor and foaming capacity to quantify the impact of surfactant types and concentrations on foam droplet surface tension and density. This enhances the model's applicability across different types and concentrations of surfactants with greater accuracy. This offers an efficient, precise, and versatile method for predicting liquid accumulation in foam-carrying liquid gas fields, thereby enhancing the efficiency and safety of gas extraction.

A universal method for determining the detergent effect of surfactants

Surfactants are indispensable in industrial applications today due to their wetting, emulsifying, dispersing, cleansing, and detergent properties. The use of surfactants extends from the cosmetic industry to the petroleum industry and beyond.Their characteristics and effectiveness can be assessed through various standardized tests, and based on these methods, their applications can be determined. However, there is a lack of a universally applicable testing method for one crucial and complex property: the detergent effect.The detergent effect refers to the removal of unwanted contaminants from a solid surface. However, cleaning is not solely attributed to the surfactant but to the appropriate combination of various factors, whose synergistic effect reduces surface contamination. The most significant factors influencing detergent effect include the characteristics and nature of the contaminants, properties of the cleaning solution (surfactant concentration and composition, water hardness, enzymes, etc.), temperature, washing time, and hydrodynamic conditions. Additionally, the presence of electrolytes, pH of the cleaning solution, and detergent foaming properties may also play important roles.Our goal was to develop a detergent effect testing methodology that is not specific to any particular application domain but offers a straightforward and easy-to-implement solution for comparing the detergent effect of various types of surfactants.•The study presents a method for determining detergent effect of surfactants.•The method is universal and suitable for the evaluation of any type of surfactant.•The method is low-cost and easy to perform.

Unlocking the Potential of Mannosylerythritol Lipids: Properties and Industrial Applications

Mannosylerythritol lipids (MELs), one of the most promising biosurfactants (BS), are glycolipids produced by yeasts or fungi, which have great environmental performance and high compatibility with the human body. MELs, besides working as typical surfactants, can form diverse structures when at or above the critical aggregation concentration (CAC), reduce the surface tension of water and other solutions, and be stable over a wide range of conditions. Among others, MELs present antimicrobial, antitumor, antioxidant and anti-inflammatory activities and skin and hair repair capacity, which opens possibilities for their use in applications from cosmetics and pharmaceutics to bioremediation and agriculture. However, their market share is still low when compared to other glycolipids, due to their less developed production process and higher production cost. This review gathers information on the potential applications of MELs mentioned in the literature since 1993. Furthermore, it also explores the current strategies being developed to enhance the market presence of MELs, in parallel with the ones developed for rhamnolipids and sophorolipids.

USE OF ETHOXYLATED ALCOHOLS WITH ANIONIC SURFACTANTS FOR ENHANCED RECOVERY

The article is devoted to the development of surfactant compositions, including a number of known anionic surfactants, in formulations with new types of nonionic surfactants - fatty alcohols with an increased degree of ethoxylation. The solubilizing properties of new types of fatty ethoxylated alcohols have been exploited during formulation development. A conductometric method was used to control the assembly of the formulations. After evaluating the stability of the resulting compositions, physicochemical properties were evaluated, including thermal stability and corrosiveness. The freezing point of the compositions was evaluated at temperatures down to minus 40 °C. The search for stable compositions was carried out for aggressive application conditions: at 90 ° C for models of mineralized formation waters having a total amount of dissolved salts in the range of 100-300 g/l. Ranges including critical concentrations of formulations at which colloidal structures are stable and exhibit maximum surface activity were evaluated. When determining the interfacial tension at the surfactant-hydrocarbon liquid solution boundary, a number of developed compositions showed ultra-low interfacial tension (less than 0.01 mN/m). Biodegradability was evaluated for compositions showing the best properties. According to the results of the assessment, biodegradability was more than 98 %, which reduces environmental risks. The results obtained by the authors show that a number of compositions collected by conductometric method are stable under aggressive conditions and can be used in the field of chemical methods for increasing oil recovery. The resulting compositions were adapted to reduce human factors in subsequent applications. The results reflect the potential of these approaches in adapting and selecting surfactant compositions for chemical waterflooding to enhance oil recovery. The development of technologies for the ethoxylation of higher fatty alcohols allows the manufacturability of processes for the production, collection and treatment of oil and gas. The development of practices for the use of new chemical technologies will expand the capabilities of subsoil users and reduce the risks associated with the use of large-scale chemical products.

Effects of surfactant types on anthracite dust wettability: Experimental and molecular simulations

To study the wetting mechanism of surfactants at the solid–liquid interface of anthracite, a combination of experiments and molecular simulation was used to explore the adsorption and wetting processes of four surfactants, namely, fatty alcohol polyoxyethylene ether N = 9 (AEO9), Triton X-100, rapid penetrant T (PRT), and sodium alkyl ether sulfate (AES) on anthracite. The wetting mechanism of surfactants on anthracite was analyzed at both macroscopic and microscopic levels by surface tension, contact angle, settling time, and changes in surface morphology and functional groups on the anthracite surface. The presence of OH-π and C = O was determined to significantly enhance anthracite wettability. The anthracite/surfactant/water system was constructed from a microscopic perspective, and the interaction energies, relative concentration distributions along the Z-axis, diffusion coefficient (D) of water molecules, radial distribution functions (RDF) of hydrophilic groups and water molecules, and coordination numbers of the components were analyzed. The results show that the wetting effect depends on the adsorption state of the surfactant at the anthracite/water interface and the strength of the interaction between the surfactant and water molecules. The addition of surfactants enhances the adsorption thickness of water molecules along the Z-axis and generates more hydrogen bonds, which play a role in fixing water molecules and lead to a decrease in the D of water molecules. RPT forms the highest number of hydrogen bonds with water molecules and has the lowest D of 0.479 × 10-5 cm2/s, indicating strong wetting ability. The RDF of O atoms in surfactants and water molecules shows a similar trend, with two peaks one strong and one weak. The coordination numbers are 1.356, 1.057, 1.003, and 0.903, respectively. The final wettability of the surfactant on the anthracite depends on the synergistic interaction between the oxygen functional groups (OGs) as compared to the coordination number of the individual OGs.

Selection Criteria for Solvent and Coagulation Medium to Modulate the Structure of Polymethylmethacrylate Prepared by Wet Phase Inversion

Polymethylmethacrylate, PMMA, with sponge or finger pores are interesting depending on the application. Our goal was to investigate parameters (Φ and Φ’) to foresee the morphology of PMMA prepared by phase inversion based on chemical composition (amount and type of solvent, non-solvent and surfactant). A literature survey was conducted with different chemical composition and analyzed by statistical tools. Sponge-like structures were obtained in systems whose Φ value is less than 0.22 or the Φ’ value is more than 0.55. Both indexes can differentiate to some extent systems that generate finger-like structures from those that generate sponge-like ones.

Understanding the Impact of Fuel on Surfactant Microstructure of Firefighting Foam

Aqueous film-forming foam is being phased out due to the environmental impacts of fluorinated surfactants contained in the firefighting foams. To develop an environmentally friendly firefighting foam, it is important to understand the factors controlling the firefighting performance of surfactants. Fuel transport through foam has been considered as a dominant mechanism for foam collapse. Therefore, the impact of fuels (heptane, octane and trimethylbenzene (TMB)) on surfactant microstructure was studied for three different types of surfactants (Capstone, Glucopon, and siloxane) that have applications in firefighting foam. Multiple techniques were used to identify the microstructure and interfacial properties of surfactants with and without exposure to liquid fuel. The ignition time of fuel vapor through foam and solubility of fuel through liquid surfactant solution were measured as well. This work shows fuel solubility has an impact on the surfactant microstructure and interfacial properties. In addition, fuel solubility and vapor pressure affect the ignition time of fuel vapors.

Surfactant Effects in Porous Electrodes for Microemulsion Redox Flow Batteries

The effect of surfactant additives on electrochemical behavior in porous electrodes was investigated using vanadium redox flow battery half-cells and the dependence of volumetric kinetics and mass transport on electrolyte, surfactant, and electrode type was explored. Without surfactant added, carbon paper electrodes demonstrated greater kinetics and transport compared to carbon felt, for a given electrolyte. Additionally, posolyte kinetics are greater than negolyte kinetics by one to three orders of magnitude, depending on the electrode type. Addition of surfactant increased electrode wettability and possibly electrochemical surface area. However, this was accompanied by a decrease in volumetric mass transport, due to stronger electrolyte-electrode interactions. The presence of sodium dodecyl sulfate (SDS) influenced posolyte and negolyte kinetics differently. Kinetics showed a dependence on electrode type and surfactant. On carbon felt, volumetric kinetics decreased for both posolyte and negolyte with SDS addition. On carbon paper, SDS decreased volumetric kinetics for the posolyte but increased (>2X) kinetics for the negolyte! This kinetic enhancement depends on surfactant chemistry: cetyltrimethylammonium bromide, a cationic surfactant, failed to increase kinetics. Furthermore, SDS did not increase areal specific resistance. These findings show the superior performance of carbon paper compared to carbon felt and suggest SDS as a possible VRFB negolyte additive.

Explore the Impact of Surfactant Type on the Stability and Separation Efficiency of Oil–Water Emulsions of Real Wastewater from Al-Basrah Crude Oil Using Microbubble Air Flotation

Explore the Impact of Surfactant Type on the Stability and Separation Efficiency of Oil–Water Emulsions of Real Wastewater from Al-Basrah Crude Oil Using Microbubble Air Flotation