Cetyltrimethylammonium Bromide Concentration Research Articles

Organoclays from acid-base activated vermiculites for oil-water mixture separations

Oily wastewater discharge causes severe environmental pollution and resource waste, requiring the development of low-cost adsorbents with good hydrophobicity. This study presents the preparation and use of a novel highly hydrophobic adsorbent based on natural vermiculite clay minerals to separate free/emulsified oil-water mixtures. Vermiculite was first activated with sulfuric acid and potassium hydroxide to increase its adsorption capacity and surface area. The sample was then modified with cetyltrimethylammonium bromide (CTAB) to change the wetting properties from hydrophilic to hydrophobic and increase oil adsorption. XRD, XRF, FESEM, BET, FTIR, and zeta potential analyses were carried out to determine changes in texture, morphology, and chemical composition of vermiculite affected by acid, base and acid-base activation. According to the results, the acid-base activation process was selected for vermiculite treatment before CTAB modification, which demonstrated a high oil adsorption selectivity (1910.6 %) compared to raw vermiculite (44.14 %). Effect of CTAB concentration on vermiculite's wetting properties was studied. The results confirmed that the acid-base activated sample modified at 0.9 mmol.L−1 near the critical micelle concentration of CTAB exhibited highly hydrophobic properties (water contact angle of 148° ± 1°). For oil-in-water emulsions, the treated adsorbent demonstrated a high oil removal efficiency of 96.4 %. Additionally, a packed layer of highly hydrophobic vermiculite was applied for free heavy/light oil-water mixture and water-in-oil emulsion separation. The performance test for separation of free oil-water mixture and water-in-oil emulsion showed high separation efficiency (all above 90 %). The reusability of highly hydrophobic vermiculite as well as the effect of oil type, the thickness of the adsorbent layer, and the height of the water phase on separation performance were also investigated.

Efficient RhB degradation and antimicrobial activity with molecular docking study of polymers doped ZnSe nanostructure

A facile coprecipitation approach was adopted to synthesize zinc selenide (ZnSe) doped with a fixed amount (3 wt%) of cetyltrimethylammonium bromide (CTAB) and different concentrations (2 and 4 wt%) of eudragit to form ternary nanostructure (NSs). Eud and CTAB inhibit the dimension and reduce the rate of recombination of NSs to intensify catalytic performance against rhodamine B (RhB) and bactericidal action against MDR Staphylococcus aureus (S. aureus). Doped ZnSe increase active sites, porosity, and surface area to enhance the degradation of RhB dye and antimicrobial efficacy to kill pathogenic S. aureus. Assessment of 4 wt% Eud/CTAB exhibited effective performance for degradation of RhB and bactericidal potential highlights an impressive 94.3 % degradation efficiency and 8.85 ± 0.05 mm of the inhibition zone against MDR S. aureus. Computational molecular docking studies suggest that NSs, such as Eud/CTAB-doped ZnSe, have the ability to inhibit the DNA gyrase enzyme in MDR S. aureus.

Surface engineering of Fe3O4@SiO2 Core–Shell nanoparticles: Role of CTAB/TEOS ratio

Core– shell Fe3O4@SiO2 nanoparticles with tunable SiO2 shell thickness and porosity were successfully synthesized using cetyltrimethylammonium bromide (CTAB) as the crosslinking agent and tetraethyl orthosilicate (TEOS) as the silica precursor. The increase in the O-H stretching peak intensity observed in the Fe3O4/CTAB and Fe3O4/CTAB/SiO2 nanoparticles was attributable to the increased number of hydroxyl groups resulting from hydrogen bonding between the head of CTAB and water molecules and the increased exposure of the SiO2 surface owing to CTAB dissolution. The shell thickness and porosity of the nanoparticles were controlled by adjusting the TEOS/CTAB ratio. Increasing the CTAB content while maintaining a fixed amount of TEOS resulted in a constant shell thickness but increased porosity. Conversely, increasing the TEOS content while fixing the amount of CTAB led to the formation of a double-shell structure with a new dense silica layer on top of the existing shell at concentrations exceeding a certain threshold. These findings provide valuable insights into the design and application of SiO2-coated nanoparticles tailored for various applications.

Tailoring polypyrrole morphology and electronic properties through CTAB-SDS self-assembly

This study explores the polymerization of polypyrrole (PPy) within a self-assembled catanionic surfactant composed of cetyltrimethylammonium bromide (CTAB) - sodium dodecyl sulfate (SDS), aiming to control its morphology and electronic properties. The research systematically investigates how varying the compositions of CTAB and SDS surfactants influence the structural and electronic characteristics of PPy. Our findings indicate that the surfactant composition predominantly impacts the shape of PPy rather than its crystallinity. Despite the absence of significant crystallinity, variations in surfactant composition notably alter the electronic properties of PPy. Specifically, an increase in CTAB content results in electrical conductivity increasing from 0.34 to 0.01 S/m. Conversely, higher SDS content enhances the bipolaron-to-polaron ratio, particularly in the C−H deformation region, contributing to improved electronic characteristics. Additionally, packing density analysis reveals that the ordered or disordered acyl chain arrangement within the catanionic surfactant system varies significantly with surfactant composition, further influencing the morphology and electronic properties of PPy. These findings provide valuable pave for designing conductive polymers with tailored electronic properties by a catanionic surfactant, where precise control over such properties is crucial.

Synthesis, Characterization, and Interaction Studies of Naphtho‐[2,3]‐furan‐Based Molecules with CTAB as Model Surfactant

AbstractThe synthesis of highly sensitive UV–visible active naphthofuran derivatives, namely naphtho‐[2,3]‐furan‐3‐yl acetate (NF), 9‐bromonaphtho‐[2,3]‐furan‐3‐yl acetate (BNF), 9‐nitronaphtho‐[2,3]‐furan‐3‐yl acetate (NNF), 9‐iodonaphtho‐[2,3]‐furan‐3‐yl acetate (INF), and naphtho‐[2,1‐b]‐furan‐4‐carboxylic acid (ONF) as solvatochromic molecules, was carried out through multistep synthetic approach. These molecules possess different substituents that tend to form micelles in cetyl trimethylammonium bromide (CTAB) aqueous system. During the micellization process, the absorption spectrum of the synthesized molecule exhibits sensitivity towards the polarity of the environment, which affects the critical micelle concentration (cmc) of CTAB. This study demonstrates that synthesized molecules can be used for estimating solvent polarity and cmc.

Waste tea as absorbent for removal of heavy metal present in contaminated water

The goal of this study is to investigate the efficacy of tea-derived absorbents for the removal of heavy metals from contaminated water. For this, absorbents were prepared from milk tea (MT) waste, Ilam tea (IT) waste, and various types of tea leaves, including Immature (IML), mature (ML), and old leaves (OL). The characterization of the absorbents revealed distinct physical and chemical properties from X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), with varying degrees of effectiveness observed across different absorbent types. Heavy metal removal efficiency was assessed using a chemical-free UV-spectrophotometer. The results show that the maximum removal efficiency for Cd using the IT absorbent reaches up to 82.14 % with 100 ppm cetyltrim ethylammonium bromide (CTAB), while the minimum removal efficiency is 32.14 % using the OL absorbent with 20 ppm CTAB. For Zn, the OL absorbent demonstrates a maximum removal efficiency of 52.59 % with 100 ppm CTAB, whereas the minimum efficiency is 3.70 % using the ML absorbent with 20 ppm CTAB. For Ni, the highest removal efficiency is achieved with the ML absorbent, reaching up to 97.73 % with 100 ppm CTAB, and the lowest is 31.82 % with the MT absorbent with 20 ppm CTAB. The addition of a catalyst further enhanced removal efficiencies in both absorbents and metals. Also, the removal of heavy metal ions using 0.05 g of tea absorbent combined with CTAB at varying concentrations. Results show that the addition of 20 ppm and 100 ppm CTAB significantly reduces metal ion concentrations from an initial 100 mg/L. The metal ion concentration decreases as CTAB concentration increases, demonstrating the effectiveness of CTAB in enhancing the absorption capacity of tea absorbent for heavy metal removal. The investigation of selective adsorption of Ni, Zn, and Cd by an adsorbent, revealing competitive adsorption behavior with Ni and Zn being adsorbed more rapidly than Cd, suggesting the impact of metal ion interference on adsorption efficiency. However, limitations were observed with certain absorbent types; for instance, immature leaves did not effectively remove Ni. Overall, this study underscores the potential of tea-derived absorbents as sustainable solutions for mitigating heavy metal pollution in industrial wastewater. Further research is needed to optimize absorbent formulations and explore their applicability in real-world environmental remediation scenarios.

Role of CTAB, and reactive radical species (HO[rad] and O2−[rad]) on the permanganate redox reaction

Permanganate-H2SO4 redox system was used to establish the role of cetyltrimethylammonium bromide (CTAB), and reactive radical species on the oxidative degradation of Congo red. The absorbance at 496 nm increases for ca. 6.0 min, and then decreases. Permanganate-Congo red redox reaction was very slow (degradation efficiency = 46 % in 180 min with kobs = 0.004 min−1 at 496 nm). The degradation efficiency was found to be 85 % in 6.0 min of reaction time with H2SO4. Congo red and permanganate interact with CTAB aggregates due to the electrostatic interactions. The decay of absorbance at 467 nm became very slow with increasing CTAB concentrations. The oxidative treatment of Congo red/MnO4− system follows first-, and complex – order kinetics with permanganate, and Congo red concentrations, respectively. The Congo red degradation efficiency remains unaffected with sodium pyrophosphate and sodium fluoride, which ruled out the possibility of Mn(III) formation as an oxidation state of manganese. Humic acid (HA) enhanced the degradation efficiency of Congo red/MnO4− system, and facilitated the in-situ formation of water soluble colloidal MnO2. The scavenger’s studies revealed that hydroxyl (HO), and superoxide (O2−) radicals were not the reactive species in the Congo red/ MnO4− redox system under our experimental conditions.

Exploring the role of aspartic acid in modulating micellization behavior of cationic cetyltrimethylammonium bromide

The study of the interaction between aspartic acid (Asp) and cetyltrimethylammonium bromide (CTAB) reveals important information about surfactant organization, surface tension, critical micelle concentration (CMC), and surface pressure. Because of enhanced surfactant solubility brought about by electrostatic interactions, Asp’s ionization lowers CTAB’s CMC. The maximal surface excess concentration falls with increasing Asp concentration, suggesting competition for surface adsorption. The minimum occupied area per surfactant molecule increases at the same time, indicating changed surfactant activity at the interface between air and water. Higher CTAB concentrations are associated with a decrease in surface tension, which suggests that when Asp concentration rises, micelle formation would be promoted. Saturation effects, on the other hand, happen at high Asp concentrations and interfere with micelle formation. These tendencies are supported by surface pressure measurements, highlighting the significance of ionic interactions in micelle behavior.Moreover, surfactant structuring is impacted by the packing parameter decreasing as Asp concentration increases. The changing balance between hydrophilic and hydrophobic interactions within the CTAB/Asp micellar complexes is further explained by variations in degree of counterion dissociation of micelles (α) values. The complex dynamics of ionic interactions and their impact on surfactant behavior in CTAB/Asp systems are highlighted by these studies.

Synthesis and characterization of hydroxyapatite coatings with superior performance for corrosion protection of Ti-6Al-4V alloy in simulated bodily fluid

Hydroxyapatite nanoparticles (HAP-NPs) were synthesized using a microemulsion (cetyltrimethylammonium bromide (CTAB) and dimethyl sulfoxide (DMSO) as surfactants) method. The influence of the optimum ratios of CTAB concentrations as surfactants in the microemulsion on HAP morphology was investigated. After dispersing the HAP powders, a high-speed spin coating process at 2500 RPM was employed to produce HAP coatings on the Ti-6Al-4V alloy. The HAP-NP properties were characterized using techniques such as XRD, FTIR, FESEM, and AFM. Studies utilizing electrochemical impedance spectroscopy (EIS) in a simulated body fluid (SBF) solution. The corrosion resistance of coated samples compared to bare substrate increased from 67 to 853.34 kΩ cm2.

Synergistic adsorption and UV degradation of perfluorooctanoic acid by amine-functionalized A-center sphalerite

Perfluorinated alkylated substances (PFAS), as a category of persistent organic pollutants, have garnered extensive concern due to their resilience against environmental degradation. Herein, we developed an amine-functionalized sphalerite (ZnS) with adjustable surface amine functional groups and Zn defects (ZnS-X%[N]) by in situ coprecipitation and simple hydrothermal method in the presence of cetyltrimethylammonium bromide (CTAB). This material demonstrated efficient PFAS adsorption and subsequent photo-induced degradation under UV irradiation. The characterization results by TEM, BET, FTIR, XPS and EPR revealed that CTAB primarily influences ZnS by modulating surface amine functionalities, zinc defect density, and enhancing its photoreductive capacity. Adsorption and kinetic degradation experiments further showed that a medium CTAB concentration in ZnS-40%[N] achieves highest PFAS adsorption capacity (Cmax: 0.201 mol kg-1), and the corresponding decomposition rate was the fastest (kde: 1.53; kdf: 1.19). This efficacy is attributed to the ZnS-40%[N]'s ideal adsorptive sites and surface shallow defects. Moreover, theoretical simulation also supports the above experimental inference. Overall, ZnS-X%[N] exhibits a synergistic effect on PFAS adsorption and degradation, showcasing its potential for environmental adaptability and practical application.

In-situ synthesis of quaternary alkylammonium ligand capped organic-inorganic hybrid halide perovskite for high pure green luminescence in display application

This study delves into the intricate dynamics of ligand engineering for the synthesis of Methyl Ammonium Lead Bromide (MAPbBr3) nanocrystals (NCs), which exhibit immense potential in optoelectronic and photovoltaic applications. Our focus centres on the role of the quaternary ammonium molecule CTAB as a ligand in stabilizing MAPbBr3 NCs. This also addresses the challenges related to the stability and surface defects of NCs that hinder their commercial viability. Employing a modified ligand-assisted reprecipitation technique (LARP) with a dual solvent system, we optimized the CTAB concentration to 0.05 mmol, resulting in MAPbBr3 NCs with an impressive 88% quantum yield. XPS and FTIR analyses confirm the presence and binding of CTAB on the NC surface. The MAPbBr3-CTAB NCs exhibit higher exciton–phonon binding energy, enhancing their optical properties. Despite an unfavourable geometric fit, CTAB is effective in surface defect passivation due to its binding, solvation, and desorption energy during the dynamic binding process. 2D-DOSY NMR reveals approximately 66% CTAB bound to the NC surface. A comparative study involving MAPbBr3-OA, OLA, and MAPbBr3-CTAB deposited on LEDs demonstrates the superior performance of the latter, achieving a luminous efficiency of 42.18 lm W−1 at 1.2 ml deposition. These findings highlight the efficacy of CTAB in achieving high-purity green luminescence, aligning with BT.2020 display colour standards and paving the way for advanced optoelectronic applications. The successful synthesis and improved performance of MAPbBr3-CTAB NCs underscore their potential as a promising material for future optoelectronic and photovoltaic technologies.

Enhancing the Antimicrobial Properties of Experimental Resin-Based Dental Composites through the Addition of Quaternary Ammonium Salts.

Secondary caries is one of the main reasons for dental filling replacement. There is a need to obtain dental restorative material that is able to act against caries-inducing microorganisms. This study explores the antimicrobial properties of cetyltrimethylammonium bromide (CTAB) or dimethyldioctadecylammonium bromide (DODAB)-modified photo-cured experimental dental composites against Escherichia coli, Streptococcus mutans, and Candida albicans. The antimicrobial activity against Escherichia coli, Streptococcus mutans, and Candida albicans was assessed by using an Accuri C6 flow cytofluorimeter, and then analyzed using BD CSampler software (1.0.264). Bacterial/yeast surface colonization was carried out by using an GX71 inverted-optics fluorescence microscope equipped with a DP 73 digital camera. For bactericidal surface analysis of each sample type, simultaneous standardization was performed using a positive control (live cells) and a negative control (dead cells). A positive correlation between the increasing concentration of CTAB or DODAB and the dead cell ratio of Escherichia coli, Streptococcus mutans, and Candida albicans was revealed. In particular, CTAB at a 2.0 wt% concentration exhibits superior efficiency against pathogens (65.0% dead cells of Escherichia coli, 73.9% dead cells of Streptococcus mutans, and 23.9% dead cells of Candida albicans after 60 min). However, Candida albicans is more resistant to used salts than bacteria. A CTAB- or DODAB-modified experimental dental composite exhibits antimicrobial potential against Escherichia coli, Streptococcus mutans, and Candida albicans after 10 and 60 min of incubation, and the antimicrobial efficiency increases with the wt% of QAS in the tested material.

Effect of surfactant and PAM on the settlement of kaolinite particles and its mechanism analysis

High concentrations of fine-grained clay minerals in tailings water are highly detrimental to environmental protection and water recycling. Using kaolinite as the study subject, this research investigates the effects of various cationic surfactants (DDA, DTAB, TTAB, CTAB) and flocculants (APAM, NPAM, CPAM) on the sedimentation of kaolinite particles. The study explores the impact of single agents, combined agents, and the sequence of their addition on kaolinite particle sedimentation. The results indicate that when using individual agents at low concentrations, CTAB outperforms TTAB, DTAB, and DDA, while APAM is more effective than NPAM and CPAM. The optimal performance is achieved with a CTAB concentration of 2×10<sup>-4</sup> mol/L and an APAM dosage of 20 mg/L. When combining agents, the best results are observed when CTAB is added before APAM. By fixing the APAM dosage at 20 mg/L and varying the CTAB concentration, the highest sedimentation rate and lowest turbidity are obtained at a CTAB concentration of 1.5×10<sup>-4</sup> mol/L. Mechanistic insights were obtained through aggregate imaging, area measurement, zeta potential testing, and contact angle testing. Cationic surfactants alter the surface properties of particles, reducing surface electronegativity and increasing hydrophobicity, which diminishes inter-particle repulsion and promotes aggregation, thereby reducing turbidity. Flocculants form larger flocs through adsorption and bridging, accelerating the sedimentation process. When flocculants and cationic surfactants are used together, the resulting flocs are more stable and larger, with an average floc area reaching 5017.6079 µm<sup>2</sup>, indicating a significant reduction in fine particles within the solution.

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.

CO2-switchable emulsion with controllable stability and viscosity based on chitosans and cetyltrimethylammonium bromide

Emulsions have extensive applications in food, cosmetics, and agriculture, while the requirements for emulsions differ in various fields. It is a challenge for one emulsion to satisfy multiple requirements in different applications. Herein, CO2-switchable emulsions with controllable stability and viscosity were prepared by a mixture of chitosans (CS) and CTAB. After adding low concentrations of CTAB (e.g. 0.5 mM), the viscous Pickering emulsions stabilized by CS alone were converted into moderate-viscous Pickering emulsions due to the competition adsorption between CS aggregates and CTAB at the oil-water interface. The transformation of emulsion types (such as Pickering and conventional emulsions) and the emulsion's stability and viscosity were controlled by CO2/N2 trigger. Furthermore, at high CTAB concentrations (≥ 0.8 mM), a novel long-term stable conventional emulsion was obtained after the CS aggregates at the oil-water interface were entirely replaced by CTAB. Compared with other stimuli, CO2 is recognized as a green trigger that doesn't cause contaminations in the system, which has potential applications in organic synthesis and polymerization. Our strategy provides a simple and effective method to smartly control the properties of the emulsions (such as the emulsion type, stability, and viscosity), obtaining an intelligent emulsion to meet different requirements in many applications.

Enhanced adsorption of Cr(VI) from aqueous solutions by CTAB-modified schwertmannite: Adsorption performance and mechanism

Schwertmannite (Sch) is recognized for its heavy metal adsorption capabilities, but is limited by several drawbacks, including a narrow pH operational range, a tendency towards agglomeration, and a relatively modest adsorption capacity, which restricts its widespread utilization. This study introduces cetyltrimethylammonium bromide (CTAB) modified Sch (CTAB-Sch), synthesized through a rapid oxidation technique using H2O2, which significantly ameliorates these limitations. The investigation finds that a CTAB concentration of 10 mM is optimal for Cr(VI) removal, with the modified sch showing significant improvements in stability, recyclability, and adsorption efficiency within a pH range of 2–7. The adsorption process is characterized as spontaneous and endothermic, conforming to pseudo-second-order kinetics and the Langmuir adsorption model, resulting in a maximum adsorption capacity of 103.02 mg/g, which is approximately twice that of its unmodified Sch. Through comprehensive experimental analysis, the efficient removal mechanism of Cr(VI) by CTAB-Sch was elucidated, involving ion exchange, electrostatic attraction, and surface complex formation. Moreover, the investigation demonstrates that CTAB plays a pivotal role in enhancing adsorption by optimizing functional group orientation, amplifying surface positive charge, augmenting hydrophilicity, and inhibiting mineral agglomeration. The findings suggest that CTAB-Sch has significant potential for treating Cr(VI)-contaminated wastewater, highlighting its advancements in adsorption technology.

Aqueous Two-Phase Flotation Combined with Gold Nanoparticle Colorimetry for Determination of Thiocyanate in Raw Milk

Thiocyanates are effective in inhibiting the growth of microorganisms in raw milk to extend shelf life, but excessive addition can cause human health problems. Currently, ion chromatography and spectrophotometry are the main methods used in industry to determine SCN, but the pre-treatment process is cumbersome and time-consuming and has low sensitivity. Aqueous two-phase flotation (ATPF) technology has the advantages of simplicity, rapidity and economy. In this study, an acetonitrile/ammonium sulfate ATPF–gold nanoparticle (AuNP) colorimetric method was developed for the determination of SCN− in raw milk, and ATPF was used to separate and concentrate SCN− in raw milk to improve the detection sensitivity under convenient and economical conditions. The separation conditions were optimized by single-factor experiments and RSM, while the detection conditions, effects of CTAB concentration, pH and reaction time, were investigated. The “aggregation–anti-aggregation” mechanism of the gold-nano colorimetric method for the determination of SCN− was investigated by UV-vis absorption spectroscopy (UV-vis) and transmission electron microscopy (TEM). Under the optimal separation and detection conditions, the SCN− concentration showed a linear relationship with A630/A520 values in the concentration range of 0–2.5 mg/L with R2 of 0.9933, limit of detection (LOD) of 0.0919 mg/L, limit of quantitation (LOQ) of 0.306 mg/L, intra-day precision of 5.3% and spiked recoveries of 80.91–101.25%. In addition, the ATPF-AuNP colorimetric method demonstrated high selectivity and stability.

Kinetics of permanganate–sulfuric acid redox reaction with cetyltrimethylammonium bromide

AbstractThe permanganate–H2SO4 redox reaction, useful in oxidative treatments under aqueous conditions, was studied spectrophotometrically in the absence and presence of cetyltrimethylammonium bromide (CTAB). The decolorization reactions were influenced by the [MnO4−], [H2SO4], and temperature. Permanganate reduction follows first‐, and complex–order kinetics with permanganate, and H2SO4 concentrations, respectively. The reduction of permanganate (Mn(VII)) proceeds through a complex formation between MnO4− and H2SO4. The characteristic absorption peaks for MnO42− (λmax = 439 and 606 nm), MnO43− (λmax = 667 nm), and MnO2 (λmax = 400–418 nm) were not appeared during the redox reaction. The KMnO4 degradation efficiency remains unaffected with sodium pyrophosphate and sodium fluoride. The results of this study demonstrated the formation of Mn(II) as the stable product in acidic reaction media. The degradation efficiency increases drastically from 15 to 100% with 2.0 × 10−4 to 16.0 × 10−4 mol/L CTAB concentration under sub‐, and post‐micellar reaction conditions, respectively. The thermodynamic parameters (activation energy = 98.8 and 43.2 kJ/mol), activation of enthalpy (96.3, and 39.0 kJ/mol), activation of entropy (16.2 and −149.5 J/K/mol), free energy of activation (93.1 and 83.5 kJ/mol) were calculated without and with CTAB, respectively. Hence, CTAB can be exploited for its multifunctional applications, and specifically for the catalytic role in the permanganate‐assisted redox reactions in future.

Interaction between methyl red and cetyltrimethylammonium bromide under the influence of sodium polystyrene sulphonate in ethanol-water binary solvent systems: A spectrophotometric investigation

This research aims to comprehensively investigate and analyze the UV–visible spectroscopic behavior of the methyl red (MR)-cetyltrimethylammonium bromide (CTAB) system under the influence of sodium polystyrene sulfonate (NaPSS) in aqueous and different volume fractions (v.f.) of ethanol (EtOH)–H2O (0.1, 0.2, and 0.3) at 298.15 ± 0.2 K. In EtOH–H2O solvent systems, the triple interactions of dyes-surfactants-polyelectrolyte (DSP) complex systems are entirely novel. MR interacts with CTAB in NaPSS in the binary solvent media (0.1, 0.2, and 0.3 v.f. of EtOH–H2O) resulting in the formation of ion-pairs at very low CTAB concentrations, far below their apparent critical micelle concentration (CMC*) reducing the absorbance, and the new complexes above the CMC* due to solubilization of the MR into CTAB micelles observed by distinct spectral shifts. The CMC* values obtained from spectroscopic data increase in the order: (CMC*)water< (CMC*)0.1< (CMC*)0.2< (CMC*)0.3. This is because of the reduced polarity or dielectric constant and increased degree of water structure disruption around the hydrophobic chains of CTAB, where micelle formation occurs at somewhat higher concentrations. The Gibbs energy of micellization (ΔGmo) increases in the order: (ΔGmo=−16.89)water <(ΔGmo=−16.17)0.1<(ΔGmo=−15.62)0.2<(ΔGmo=−15.38)0.3, which further supports the inhibitory effect of increasing ethanol content towards micellization. In the post-micellar region, the decrease in hydrophobic interactions and an increase in electrostatic interactions lead to a rise in the overall binding constant value. This means that, when NaPSS is present, the stronger electrostatic interactions in the post-micellar region contribute significantly to the increased binding of CTAB micelles with MR. The tautomeric activity of MR and the solvent composition played a prime role in affecting the interaction mechanism, as evidenced by the blue and red spectral shifts.

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.