Cationic Surfactant Cetyltrimethylammonium Bromide Research Articles

Highly selective aptasensor for optical detection of whole cell gastrointestinal pathogen Shigella dysenteriae at label-free liquid crystal–aqueous interface

This paper describes a label-free liquid crystal (LC)-based biosensor for a rapid and straightforward detection of whole cell Shigella dysenteriae at aqueous interfaces using a bacteria-specific aptamer. The stimuli-receptive properties of LCs induce a change in the orientational ordering of molecules at the LC–aqueous interface. This interfacial phenomenon has been utilized to record target binding interactions of the biosensor. The homeotropic LC alignment at the glass–LC and the aqueous–LC interfaces was obtained using the aligning agent dimethyloctadecyl [3-(trimethoxysilyl)propyl] ammonium chloride and the self-assembling property of the cationic surfactant cetyltrimethylammonium bromide, respectively. The introduction of the negatively charged Shigella aptamer causes the homeotropic molecules to morph to a planar/tilted ordering. Upon adding a small quantity of Shigella cells in liquid media, the aptamer–bacterium interaction causes a redistribution of the surfactant at the LC–aqueous interface, restoring the homeotropic alignment. This results in a bright-to-dark optical change observed under a polarizing optical microscope, thus implying the presence of the microbes. This reported aptasensor demonstrates high specificity, with the limit of detection being 30 CFU/ml within a linear range of 1–105 CFU/ml. To test the utility of this system, the sensor was also tested with close taxonomic relatives S. dysenteriae as well as real samples from the food chain. This proposed LC-based sensor offers several advantages over conventional detection techniques for a quick and convenient way for the detection of whole cell targets.

Micellization and Physicochemical Properties of CTAB in Aqueous Solution: Interfacial Properties, Energetics, and Aggregation Number at 290 to 323 K

This work reports a detailed investigation of the micellization of the cationic surfactant cetyltrimethylammonium bromide (CTAB) over the temperature range of 290–313 K. Conductometry, tensiometry, fluorimetry, and isothermal titration calorimetry (ITC) were used to study the overall solution behavior of amphiphilic self-aggregation. The CMC values showed a trend of first declining and then rising with a minimum temperature of 298 K. The adsorption at the air–water interface and micellization processes of CTAB are both spontaneous. The enthalpy of CTAB micellization is negative at 290 K and increases negatively as the temperature rises. The interfacial parameters—maximum surface excess concentration (Γmax), minimum area per molecule (Amin), standard free energy of adsorption (Amin), and surface pressure at CMC (ΠCMC)—were calculated using surface tension data. The aggregation numbers (N) of CTAB micelles and others (SDS and CHAPS) determined at different [surfactant]>CMC by the static fluorescence quenching method were used to find out the N values at CMC (or NCMC). The results revealed that the NCMC values were 48, 54, and 4 for CTAB, SDS, and CHAPS micelles, respectively. Temperature-dependent NCMC by the ITC method was also examined for the studied surfactants. Additionally, the ITC-determined specific heat of micellization was used to find out the extent of water penetration into the micelle interior of up to 8, 7, and 3 hydrocarbons for CTAB, SDS, and CHAPS, respectively.

Viscoelastic behavior of wormlike micellar solutions formed by an aspartame-based bicephalous anionic surfactant.

Innovation in the molecular design of surfactants holds great potential for developing novel soft materials with unique properties. A surfactant with a long alkyl tail is expected to form giant aggregates with intriguing behavior. However, molecules with a large hydrophobic group often suffer from poor solubility in solutions, inhibiting the aggregation process. Herein, a new aspartame-based bicephalous anionic surfactant, disodium stearoyl-L-aspartyl-phenylalanine (C18-AP-2Na), has been synthesized. C18-AP-2Na showed excellent compatibility with the cationic surfactant cetyltrimethylammonium bromide (CTAB) and resulted in transparent viscoelastic mixed systems over a wide range of molar ratios and concentrations. Moreover, when CTAB and C18-AP-2Na were mixed with an equimolar charge ratio, the viscosity increased consistently from 61 mPa s (0.13 wt%) to an astonishing 14 000 Pa s (13.2 wt%). Cryo-TEM images revealed a network of extensively entangled wormlike micelles with cross-sectional diameters of 4-5 nm and lengths extending up to several micrometers at a C18-AP-2Na/CTAB molar ratio of 5 mM : 10 mM. The presence of long alkyl tails is the origin of wormlike micelle elongation. Different from other conventional anionic surfactants, C18-AP-2Na is distinguished by the amino acid unit near the head group. The extended molecular structure is not linear shaped. C18-AP-2Na is able to combine with CTAB molecules through electrostatic attractions while avoiding the too close contact of the alkyl tails. In this way, the formed ionic pairs remain hydrated in solutions instead of being precipitated. In addition, due to the strong attractions between the head groups of C18-AP-2Na and CTAB, the inorganic ions are ineffective to shield the head group charges. The viscosity of the mixed solutions remained nearly unchanged even with NaCl concentrations of up to 5%, demonstrating significant salt resistance. This work utilizes the advantages of the amino acid and develops stable cationic/anionic mixed solutions with strong viscoelasticity. The excellent compatibility as well as the strong salt resistance make the formulations promising for applications in oil recovery, cosmetic formulations, and the creation of smart materials. The self-assembly principles of surfactants demonstrated here also offer valuable insights for designing new viscoelastic systems and molecular structures.

Adsorption kinetics and solubilisation of ciprofloxacin in quaternary ammonium-based surface-active compounds: experimental and computational study.

The adsorption and aggregation of amphiphiles at different solvent interfaces are of great scientific and technological importance. In this study, interfacial tension measurements of surface-active compounds-ionic liquid 2-dodecyl-2,2dimethylethanolammonium bromide (12Cho.Br) and cationic surfactant cetyltrimethylammonium bromide (CTAB)-were conducted both in the absence and presence of ciprofloxacin (CIP). Equilibrium interfacial tension (EIFT) measurements and conductivity data demonstrate the effect of CIP on the critical micellar concentration and surface excess concentration of 12Cho.Br and CTAB. Additionally, dynamic interfacial tension (DIFT) measurements were performed to compare the interfacial tension of pure 12Cho.Br and CTAB solutions, as well as those in the presence of the drug (with and without 0.3% acetic acid), as a function of time. The DIFT analysis revealed that the adsorption of 12Cho.Br and CTAB at the air-water interface followed a mixed diffusion-adsorption controlled mechanism. The adsorption processes of 12Cho.Br and CTAB molecules were studied over short time intervals (t → 0) and longer time intervals (t → ∞). The adsorption behaviour was correlated with concentration and the presence of energy barriers. In the presence of CIP, the diffusion coefficient was compared to that of the pure 12Cho.Br and CTAB systems to assess its effect on adsorption and to validate the participation of CIP in DIFT relaxations. Additionally, DIFT measurements were employed to investigate CIP solubility in different SAC systems. Data from the relaxation profiles across a range of concentrations were used to determine the solubility limit of the drug molecules. The solubility data obtained from DIFT correlates strongly with the UV spectroscopy results. Furthermore, DFT calculations provide insights into the frontier orbital structures and physicochemical parameters of complex formations.

Spectrophotometric determination of quercetin using micelles of cetyltrimethylammonium bromide in a low ratio methanol–water mixture

A simple and achievable UV-Vis spectrophotometric method for the micro-quantitative determination of quercetin has been developed and validated. This method relies on the formation of supramolecular assemblies of quercetin (QR) and the cationic surfactant cetyltrimethylammonium bromide (CTAB) in a 5 % methanolic aqueous solution. In this solvent medium, CTAB in the presence of QR has a critical micelle concentration of 1.2·10-3 mol l-1 at 24 °C, determined through conductometry. Important analytical parameters such as wavelength, composition of methanol-water mixture, CTAB concentration (cCTAB), and pH were optimized. Under the optimum experimental conditions (l = 397 nm, 5 % methanol as solvent, cCTAB = 2.0·10-3 mol l-1, and pH = 6.0), Beer's law was valid for QR concentrations up to 16.9 mg ml-1. The Ringbom optimum QR concentration range was 1.0 - 16.9 mg ml-1. The method sensitivity was 2.03·104 l mol-1 cm-1 (the molar absorptivity) and 0.13 mg ml-1 (limit of detection). The applicability of the proposed method for quantifying QR in pharmaceutical formulations was demonstrated. Furthermore, the proposed UV-Vis spectrophotometric method was successfully applied to the reliably assay of QR, even in the presence of vitamin C.

Effect of Mixed Surfactant on Evaporation Driven Salt Crystallization Morphology in Sessile Droplets.

Extensive studies have been conducted to manipulate the morphology of sodium chloride salt crystals to tailor their physical and chemical properties. Among the myriad factors considered, the effects of the substrate and additives have profound impacts on the types of salt depositions. Surface charge effects and various ionic surfactants influence ion movement, resulting in diverse crystal morphologies. This manuscript aims to provide a consolidated summary by concurrently studying multiple effects to uncover the salt crystal morphology under the influence of two oppositely charged ionic surfactants on charged and neutral surfaces. The cationic surfactant cetyltrimethylammonium bromide induces skeletal crystal growth by retarding salt precipitation until supersaturation is reached. Conversely, the anionic surfactant sodium dodecyl sulfate hinders ion diffusion at the three-phase contact line. Each surfactant effect is dominant at higher molar concentrations. Surface charge affects the amount of surface adsorption and free-moving ions within the saline surfactant droplets, greatly influencing the number of salt crystals formed on the neutral substrate. However, charge neutralization at the highest concentrations of both surfactants nullifies the surface charge effect, resulting in practically indistinguishable salt crystals with similar sizes and numbers, leading to only a small area difference of 1461 μm2. This study provides insights into the kinetics of crystallization under the combined influence of anionic, cationic, and surface charge interactions. The findings can serve as a future reference for predicting and controlling ionic interactions and crystal morphology.

A simple technique for the determination of molybdenum (Ⅵ) based on dispersive surfactant micelle-mediated extraction and image colorimetric analysis

ABSTRACT In this study, the potential of dispersive surfactant micelle-mediated extraction combined with image colorimetric analysis was assessed for the extraction, preconcentration, and determination of molybdenum (VI) in environmental samples. In this approach, the cationic cetyltrimethylammonium bromide surfactant (CTAB) was utilised as a complexing and extraction agent, and ethanol was chosen as a dispersive solvent and surfactant self-assembly agent. Initially, a mixture of CTAB and ethanol is injected into a test tube, resulting in the formation of a cloudy solution due to the dispersion of CTAB particles in the aqueous phase. In this step, coloured ternary complexes obtained from the reaction of the Mo(VI) ions with pyrogallol red (PR) in the presence of iodide ions are extracted by CTAB through a surfactant self-assembly process. After centrifuging, the surfactant-rich phase was dissolved in 1 mL of dimethylformamide (DMF) and analysed using a smartphone-based self-constructed colorimeter and a commercial UV-Vis spectrophotometer. In the mentioned colorimeter, digital image analysis of the final solution was performed based on the RGB (Red, Green, Blue) colour model, and the value of the R channel was used to acquire the analytical signal. Under optimal conditions, a linear range of 5–100 μg L−1 and a limit of detection (LOD) of 2.1 μg L−1 were achieved using a self-constructed colorimeter. Additionally, linear range of 15–250 μg L−1, with a LOD of 3.3 μg L−1, was obtained through UV-Vis spectrophotometric analysis. Ultimately, the proposed method was successfully utilised to determine Mo(VI) in various aqueous samples, with satisfactory recoveries ranging from 96 to 109%.

Electrochemical detection of catechol with a disposable carbon nanotube paste electrode modified with CTAB

Abstract The accurate and rapid detection of catechol which is a class of highly toxic organic phenolic compounds, is of great importance for the protection of environment and human health. In this work, a novel electrochemical sensor for catechol was constructed by modifying multi-walled carbon nanotube paste microelectrode with a cationic surfactant of cetyltrimethylammonium bromide (CTAB) through a simple and controllable adsorption method. Electrochemical experiment results show that the modified electrode has good electrocatalytic effect to the electrochemical response of catechol. The electrochemical response mechanism of the sensor to catechol were investigated through using many analytical methods, including scanning electron microscopy, energy-dispersive spectroscopy, Fourier-transform infrared spectroscopy, Raman spectroscopy, and electrochemical techniques. Under the optimal fabrication and application conditions, the response current of catechol on the sensor exhibits a good linear relationship with its concentration from 1.0 μmol/L ~ 7.0 mmol/L with a sensitivity of 1.33 nA/(μmol/L) and a low detection limit of 15 nmol/L (S/N = 3). Applying the sensor in the detection of catechol in tap water samples and urine samples, the results were satisfactory, indicating its good application prospect.

Polyelectrolyte complex coatings based on PSS/CTAB for enhanced antifogging and antibacterial performances

Antifogging and antibacterial properties are both essential in biomedical examination and diagnostics to ensure clear visibility and prevent potential bacterial infections. However, it is extremely challenging to integrate both functions on one surface. Herein, this study presents a rapidly assembled polyelectrolyte complex (PEC) coating, which can be applied to different transparent substrates through a facile combination of anionic polystyrene sulfonic acid (PSS) and cationic surfactant cetyltrimethylammonium bromide (CTAB). Unlike traditional superhydrophilic anti-fogging mechanisms, this coating leverages the hygroscopic properties of polyelectrolyte complex groups, ensuring effective anti-fogging performances across a wide temperature range. Additionally, the incorporation of quaternary ammonium compounds (QACs) within the PEC complex confers strong bactericidal properties to the coating. The resultant coating exhibits excellent surface adhesion and robust resistance to water immersion, and low cytotoxicity. With its dual antifogging and antibacterial properties, this coating shows significant promise for diverse applications in medical diagnostic and detection lens equipment.

Effects of Surfactants on Oil Droplet Demulsification in Oil-in-Water Emulsions under an Electric Field: A Molecular Dynamics Study.

The application of an electric field to demulsification of oil-in-water (O/W) emulsions has received extensive attention. However, microcosmic information about the effect of surfactant type on the demulsification of an O/W emulsion under an electric field is still rare. In this work, the effects of cationic surfactant cetyltrimethylammonium bromide (CTAB) and anionic surfactant sodium dodecyl sulfate (SDS) on oil droplet demulsification in an emulsion under a pulsed-DC electric field were studied by molecular dynamics (MD) simulation. The MD simulation results show that oil droplets underwent directional movement under the action of an electric field. The larger the electric field strength, the shorter the time required for the oil droplets to coalesce. However, the movement direction of the oil droplets in the electric field was different depending on the type of surfactant. Compared to oil droplets containing SDS, oil droplets containing CTAB molecules exhibited faster deformation and easier migration coalescence under low electric field strength. It was mainly attributed to the fact that the deformation of oil droplets will be accelerated when oil droplets contain asphaltene molecules and surfactant molecules with different electronegativities under an electric field. During the demulsification of oil droplets containing CTAB molecules, CTAB molecules generated electrostatic attraction with asphaltene molecules in adjacent oil droplets, strengthened the interaction between oil droplets, and promoted the demulsification of oil droplets. In the process of oil droplet demulsification containing SDS molecules, the potential energy of the electrostatic interaction between oil droplets did not change, and the demulsification mainly depended on the van der Waals force between oil droplets.

Fabrication and characterization of carvacrol encapsulated gelatin/chitosan composite nanofiber membrane as active packaging material

In this study, carvacrol was effectively encapsulated in gelatin/chitosan composite nanofiber membrane using the electrospinning method with the help of the cationic surfactant cetyltrimethylammonium bromide (CTAB). The effects of CTAB (0.0%, 1.0%, w/w) and bioactive carvacrol (0.0%, 1.0%, 3.0%, 5.0%, 7.0%, 10.0%, w/w) on the structural, physicomechanical, antibacterial, and antioxidant characteristics of the nanofiber membranes were investigated. The results demonstrated that the antibacterial and antioxidant characteristics of the gelatin/chitosan composite nanofiber membrane (GC) and GC-CAR membrane (with the addition of 1.0% carvacrol) were unsatisfactory. As carvacrol and CTAB were both added, the elongation at break, antibacterial, and antioxidant properties of the nanofiber membranes significantly improved (p < 0.05), while the water vapor permeability (WVP) significantly decreased (p < 0.05). When the added amount of carvacrol was 5.0% (w/w), the nanofiber membrane (GC-CAR5-CTAB) exhibited the best antioxidant and antibacterial performance. Finally, the GC-CAR5-CTAB membrane was applied to the preservation of strawberries and Erjingtiao chilies, and their shelf life was effectively extended. The above results indicate that the nanofiber membrane prepared in this study has great potential for application in food-active packaging.

Effects of liquid-phase carbon combining surfactant coatings on the performance of LiMn0.2Fe0.8PO4 cathode materials

Efforts to reduce the particle size of LiFexMn1-xPO4 materials and apply conductive carbon coatings have yielded substantial benefits in terms of obtaining lithium-ion batteries (LIBs) with enhanced electrochemical performance. However, LiFexMn1-xPO4 materials with small particle sizes and uniform carbon layers cannot be obtained by the conventional high-temperature solid-phase method, which is the most convenient and applicable method for the industrial-scale preparation of the cathode materials used in commercial LIBs. The present work addresses this issue by applying the cationic surfactant cetyltrimethylammonium bromide (CTAB) in conjunction with LiMn0.2Fe0.8PO4 (LMFP) particles, and obtaining a carbon layer by replacing the conventional in-situ solid-phase carbon coating process with a secondary liquid-phase coating process using sucrose as the carbon source. The CTAB surfactant is observed to be uniformly adsorbed on the surface of LMFP particles, and maintains small LMFP particle sizes by operating as a dispersant preventing their agglomeration. Additionally, the carbon network formed by CTAB pyrolysis acts as an intermediate medium ensuring that the conductive carbon layer is uniformly and firmly adhered to the LMFP particle surfaces at a high preparation temperature of 680°C. This composite carbon layer is demonstrated to enhance lithium-ion transport, while concurrently acting as a barrier interfering with manganese diffusion within the electrolyte during charge-discharge cycling. As a result, the optimal LMFP-based cathode material achieves reversible specific capacities of 160 mAh g−1 and 120 mAh g−1 at charge-discharge rates of 0.1 C and 5 C, respectively, and the capacity retention is 88 % after 500 cycles at 1 C. Hence, the results verify that the proposed surfactant-mediated liquid-phase carbon coating process is an effective method for enhancing the overall electrochemical performance of LMFP-based cathode materials.

Understanding the Dynamics of Matrix-Fracture Interaction: The First Step Toward Modeling Chemical EOR and Selecting Suitable Fracturing Fluid in Unconventional Oil/Gas Recovery

Summary The effects of chemical additives on mitigating water blocking and improving oil recovery were experimentally examined for gas-water and oil-water systems in spontaneous imbibition cells. In these attempts, two factors are critically important: (1) understanding the physics of the interaction, whether it is co- or countercurrent, and (2) characteristics of the chemical additives to suitably orient the interaction for specific purposes (accelerate/decelerate matrix-fracture interactions). Co- and countercurrent imbibition experiments were conducted on sandstone rock samples using various oil samples (viscosities between 1.37 cp and 54.61 cp) as well as gas (air). The selected new-generation chemical additives included deep eutectic solvents, cationic/anionic/nonionic surfactants, and inorganic and organic alkalis. We observed that the functionality of the chemicals varied depending on the fluid type, interaction type (co- or countercurrent), and application purposes. For instance, chemicals such as the cationic surfactant cetyltrimethylammonium bromide (CTAB) significantly reduced water invasion into the gas-saturated sandstone cores during fracturing, while chemicals such as the nonionic surfactant Tween® 80 provided considerable oil recovery improvement in the oil-saturated sandstone cores. The surface tension and wettability of the rock surface are crucial factors in determining the suitability of chemicals for mitigating water blockage. In terms of oil recovery, certain chemical additives, such as O342 and Tween 80, may result in a lower recovery rate in the early stage because of their strong ability in interfacial tension (IFT) reduction but could lead to a higher ultimate recovery factor by altering the wettability. Additionally, the introduction of chemicals resulted in notable spontaneous emulsification, especially in countercurrent imbibition, thereby enhancing oil recovery. The spontaneous emulsification and its stability are influenced by factors such as oil drop size, boundary condition, interaction type, IFT, wettability, as well as rock surface charges. The results have implications for understanding the physics and dynamics of matrix-fracture interactions in co- and countercurrent conditions. In addition, they serve as the first step toward selecting appropriate chemical additives in hydraulic fracturing fluid design and enhancing oil recovery in unconventional reservoirs.

Ibuprofen removal by modified natural zeolite: characterization, modeling, and adsorption mechanisms

AbstractBACKGROUNDDeveloping robust technologies to remove emerging pollutants from water is urgent since conventional treatments are not technically prepared to remove them. This paper investigated the ibuprofen (IBU) adsorption capacity onto natural zeolite (NZ) and hydrothermally modified zeolite in an acidic medium followed by impregnation with the cationic surfactant cetyltrimethylammonium bromide (CTAB) (MZHT‐CTAB). The materials characterization included scanning electron microscopy (SEM), X‐ray diffraction (XRD), atomic absorption spectroscopy (AAS), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA/DTG), N2 adsorption/desorption isotherm (BET), Zeta Potential (ZP), and Point of Zero Charge (pHPZC). The adsorptive capacity studies were carried out by varying the pH solution, a kinetic study at three concentrations (25, 50, and 100 mg L−1), and the contaminant concentration influence (5–100 mg L−1).RESULTSThe results showed that the MZHT‐CTAB obtained both the highest removal efficiency (~ 37%) and the highest adsorption capacity (~ 14 mg g−1) at pH 5.0. The Pseudo Second‐Order (PSO) model, which showed the best fit to the experimental data, is significant as it indicates the reliability of our results. The maximum adsorption capacity for the concentration of 100 mg L−1 was 11.93 mg g−1. According to Giles's classification, the isotherm was classified as S‐3 type, indicating the competition between the adsorbate and water molecules for the active sites on the adsorbent surface.CONCLUSIONThe adsorption studies demonstrate that the novel adsorbent (MZHT‐CTAB) is highly effective in removing IBU, presenting a significant removal capacity and feasibility. This promising result contributes to the ongoing search for alternative materials for water treatment. © 2024 Society of Chemical Industry (SCI).

Molecular interactional study of SDS and CTAB in aqueous medium of anti-HIV drugs (Emtricitabine and Lamivudine) at different temperatures: A physicochemical investigation

The present study deals with the interactions of Emtricitabine and Lamivudine (anti-HIV drugs) with anionic surfactant sodium dodecylsulphate (SDS) and cationic surfactant cetyltrimethylammonium bromide (CTAB) at (298.15–313.15) K temperature range by volumetry, compressibility and viscometric approach. The experimental values of sound velocity and density are used to compute various parameters such as apparent molar volume (φv), isentropic compressibility (κs), and apparent molar adiabatic compression (φκ) by employing cosphere overlap model. Relative viscosity parameter (ηr) evaluated from viscosity data also helps to understand various interactions prevalent in surfactant-drug-water ternary system. This attempt of extracting information about various physicochemical interactions of anti-HIV drugs with surfactants can prove beneficial to develop novel anti-HIV agents with better viral resistance activity.

CTAB-induced synthesis of two-dimensional copper oxalate particles: using l-ascorbic acid as the source of oxalate ligand.

Copper oxalate is typically synthesized through a precipitation reaction involving copper salts mixed with oxalic acid or oxalate solutions. However, in this study, we were successful in synthesizing well-formed square-like copper oxalate particles under liquid-phase conditions at ambient temperature and pressure using ascorbic acid as the source of the oxalic acid ligand. The addition of cationic surfactant cetyltrimethylammonium bromide (CTAB) caused the morphology of copper oxalate particles to undergo a transition from three-dimensional to two-dimensional. And the inhibition of the assembly of primary copper oxalate nanocrystals along the [001] direction became stronger with the increase of CTAB concentration. The impact of CTAB on the crystallization, growth, and self-assembly processes of primary copper oxalate nanocrystals was analysed using various testing methods. Based on these analyses, the possible mechanism of CTAB-induced synthesis of two-dimensional copper oxalate particles was finally proposed.

Xanthan gum short-chain modified TiO2 nanoparticles for the preparation of high-stability foam to effectively improve the efficiency of foam oil repulsion

Nanoparticles excel in foam stability enhancement. In this experiment, xanthan gum (XG) short links were branched on the surface of TiO2 nanoparticles, and the synthesis of novel nanomaterials was verified by analyzing the structure of the nanoparticles by FT-IR, XRD, and XPS, and investigating the dispersion of the nanoparticles by using SEM as well as capturing the cross-sectional images of XG-TiO2 by using TEM and performing elemental analyses. The foams prepared by using cationic surfactant Cetyltrimethylammonium bromide (CTAB) and XG-TiO2 synergistically had excellent performance, and XG-TiO2 was able to effectively prevent the disproportionation reaction of the foams. By adding hydroxide and changing the air pressure, the half-life and foaming volume of the prepared foams were compared and analyzed, and the half-life of the foams was more than twice as much as that of the traditional materials, and the foam morphology of the foams with XG-TiO2 was smaller and more homogeneous. When XG-TiO2 foam was tested for core drive, the total crude oil recovery reached 81.2 %, which was 45.4 % higher than the water drive recovery. This experiment demonstrated the potential of XG-TiO2 nanoparticles in enhancing foam stability and foam drive application.

Dynamic insights of volumetric and viscometric exploration of Surfactant-QAs behavior in aqueous medium at varied temperatures; molecular docking and antimicrobial perspectives“

Using density (ρ), sound speed (u), viscosity (η), molecular docking and antimicrobial study analyses, this work examined the intermolecular interactions that occur between Quaternary ammonium salts (QAs) (0.005, 0.010, 0.015 molkg−1) and cationic surfactant CTAB (Cetyltrimethylammonium bromide) in aqueous solutions at 298.15 K to 313.15 K at an interval of 5 K. The Quaternary ammonium salts taken are: Tetraethylammonium bromide (TEAB), Tetra propylammonium bromide (TPAB), and Tetrabutylammonium bromide (TBAB). To comprehend and deduce the interactions, apparent molar volumes (Vϕ), apparent molar isentropic value (κS,ϕ), isentropic compressibility (κS), and acoustical parameters (Lf),(RA),(Z) and ([U]) values have been computed using the measured (ρ) and (u) data whereas relative viscosity (ηr) and viscous relaxation time (τ) values have been deduced from viscosity data. These parameters collectively provide a comprehensive understanding of the structural rearrangement of amphiphilic molecules at the interface and the relative contributions of hydrophobic and electrostatic interactions between the surfactant and aqueous solutions of QAs. Additionally, both molecular docking and antimicrobial investigations have also been performed; molecular docking facilitated the examination of interactions between ligands and proteins. Whereas, antimicrobial studies help to evaluate the impact of gram-negative bacteria (S. typhi, P. aeruginosa) and gram-positive bacteria (S. aureus, B. cereus) on CTAB in the presence of aqueous solutions containing TBAB.

Effects of ion doping on the dielectric and electro-optical properties of chiral nematic liquid crystal

This study presents experimental findings pertaining to the use of the cationic surfactant cetyltrimethylammonium bromide (CTAB) as a dopant dispersed in cholesteric liquid crystal. The impact of the additive on the electrical and dielectric properties was investigated by dielectric spectroscopy. Compared with that in the pure counterpart, the dielectric relaxation frequency increased due to the added ions in the cholesteric liquid crystals impregnated with 0.01–0.5-wt% CTAB. Furthermore, by analyzing the dielectric spectra in a specific frequency range, the DC conductivity, ion density, and diffusion coefficient were calculated and compared. By fitting the experimental data into the Arrhenius equation, the activation energy was obtained as well. Our experimental results illustrated that all these physical properties were strongly dependent on the CTAB concentration and the temperature. This work also involved the electro-optical measurement in combination with the observation of optical texture. The ion addition provoked electrohydrodynamic flows in a surfactant-dispersed mixture, generating a homogeneous and transparent uniform lying helix state between two low-transmission optical states—the focal conic and dynamic scattering states. The operating frequency range of the dynamic scattering state was significantly broadened by the ionic dopant.

Effect of TX-100 on solubilizing power of CTAB and CPC for H Acid: An experimental and computational analysis

The present research work investigates the solubility of an anionic dye 8-amino-1-naphthol-3,6-disulfonic acid (H Acid) within the micellar mediaof two cationic surfactants cetylpyridinium chloride (CPC) and cetyltrimethylammonium bromide (CTAB) as well as in the mixed micellar mediaof each cationic surfactant with Triton X-100 (TX-100). The data from differential absorption spectroscopy across a concentration range spanning from pre-micellar to post-micellar regions was used to determine the degree of solubilization by calculating the partition coefficient (Kx), binding constant (Kb) and Gibbs free energy associated with the relevant processes. Electrical conductivity of each cationic surfactant in the presence of H Acid was recorded in aqueous media and used to determine the CMC and subsequent thermodynamic parameters including entropy (ΔSm), enthalpy (ΔHm) and Gibbs free energy change (ΔGm) associated with the process of micellization. The computational analysis was carried out with GAUSSIAN 09 using a 6-311G + basis set with a DFT/ B3LYP hybrid approach and each set of energy minimization was executed to perform frequency calculations for Frontier molecular orbital analysis and to evaluate absorption spectra. Moreover, the molecular electrostatic potential surfaces (MESP) were also computed to find their suitable hydrophobic and hydrophilic interactions.