Aqueous Solutions Of Cetyltrimethylammonium Bromide Research Articles

Effect of glycerol on micellization of quasi-binary mixture of zwitterionic cocamidopropyl hydroxysultaine and cetyltrimethylammonium bromide in aqueous solution

The micellization behavior of quasi-binary mixture of zwitterionic cocamidopropyl hydroxysultaine (CAPHS) with cationic cetyltrimethylammonium bromide (CTAB) was investigated both in aqueous solution and in glycerol-water. Both the tensiometric and the conductive techniques were adopted to determine the critical micelle concentrations (cmc) of individual and mixed surfactants. In the framework of the regular solution theory and based on the pseudophase separation model, some micellization and thermodynamic parameters were estimated by the Rubingh’s and the Clint’s models. The results indicate that the nonideal mixing of CAPHS with CTAB and the synergistic interaction between them play vital roles on the reduction of mixed cmc, the amplitude of synergistic interaction depends on the composition of mixture and the presence of glycerol induces the increase in the individual and mixed cmc values and the change of the participation of CAPHS in mixed micelle with the composition in bulk solution. The electrostatic repulsion, the diversity of molecular conformation and the steric hindrance can account for the formation of mixed micelle and the difference in micellar composition. Thermodynamic parameters show that the entropy makes overwhelming contributions on the spontaneous process of micellization, the release of mixing heat makes the stable mixed micelle formed and the presence of glycerol makes for reducing the contribution of entropy and forming the more stable mixed micelle. These findings help with understanding the interaction behavior between two species and the effect of glycerol and further providing some information for the design of the related surfactant formulations.

Micelle-mediated chemiluminescence of 6-aza-2-thiothymine-protected gold nanoclusters for carbazochrome sodium sulfonate detection

Chemiluminescence (CL) intensity of luminol-H2O2 system was dramatically enhanced by cetyltrimethylammonium bromide (CTAB) micelle-mediated 6-aza-2-thiothymine-protected gold nanoclusters (ATT-AuNCs). It is proved that spherical micelles of CTAB in aqueous solution improved the dispersity of ATT-AuNCs, thus enhancing their catalytic activity, which brought in the increased CL intensity of luminol-H2O2 system. Carbazochrome sodium sulfonate (CSS) with a hemostatic containing tetrahydroindole structure broke the spherical micelles and notably quenched the CL intensity of luminol-H2O2-CTAB-ATT AuNCs system. Based on these results, a simple, fast, and sensitive CL method has been developed for the detection of CSS with a linear range of 0.25–25 μM and a detection limit of 0.11 μM. The method has also been successfully applied to the determination of CSS in serum with satisfied recoveries in the range of 89.6 % to 103.7 %. This study not only provides an effective approach for CSS detection but also paves the way for AuNCs-based CL applications.

Influence of isopropanol on the rheological behavior of wormlike micelles

Abstract The influence of replacing water with isopropanol (IP) on the rheological properties of aqueous solutions containing wormlike micelles (WLMs) prepared by mixing cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal) at 25 °C was investigated. Viscosity of CTAB aqueous solutions exhibits two maxima and one minimum with increasing amounts of NaSal, consisting of entangled WLMs. When water is replaced by increasing amount of IP, the viscosity maxima and the minimum changes drastically. The elastic plateau modulus G° of these solutions remains almost the same with increasing IP contents (up to ∼5 wt%), whereas their relaxation time changes drastically. Critical micelle concentration (CMC) of CTAB has increased with further IP addition, indicating an increase in the micellar hydrophilicity. For WLMs at minimum viscosity, increasing addition of IP (>5.0 %) to WLMs at maximum and minimum viscosities, leads to a drastic decrease in the elastic modulus G°, indicating the formation of smaller micellar aggregates. The influence of IP as a co-solvent on the WLMs rheological properties is also compared to that of glycerol and 1,3 butanediol (1,3 BD) for the same NaSal/CTAB viscoelastic system.

Tunable molecular packing modes via H- or J-aggregates in the supramolecular helical nanostructures from an achiral C3 symmetric molecule.

The self-assembly of a C3-symmetric molecule benzene-1,3,5-tricarboxylate substituted with methyl cinnamate (BTECM) has been investigated by a reprecipitation method in H2O and cetyltrimethylammonium bromide (CTAB) aqueous solution, respectively. The nanostructures and characteristics of the assemblies were monitored by UV-Vis spectroscopy, fluorescence (FL) spectroscopy, circular dichroism (CD) spectroscopy, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). It was found that helical nanostructures were successfully assembled from the achiral C3 molecule BTECM. More importantly, the helices aggregated via different packing modes in H2O and CTAB aqueous solution. In H2O, the nanostructures underwent a process of particles, fibers and helices via H-type aggregate upon aging. In the case of CTAB aqueous solution (1.2 mM), the helices were translated from particles and the molecules were inclined to aggregate via the J-type mode. In addition, the aggregation process could be accelerated by raising the temperature proved by UV-Vis spectra. A molecular aggregation mechanism was proposed based on the experimental results.

Light Responsiveness and Assembly of Arylazopyrazole-Based Surfactants in Neat and Mixed CTAB Micelles.

The self-assembly of an arylazopyrazole-based photosurfactant (PS), based on cetyltrimethylammonium bromide (CTAB), and its mixed micelle formation with CTAB in aqueous solution was investigated by small angle neutron and X-ray scattering (SANS/SAXS) and UV-vis absorption spectroscopy. Upon UV light exposure, PS photoisomerizes from E-PS (trans) to Z-PS (cis), which transforms oblate ellipsoidal micelles into smaller, spherical micelles with larger shell thickness. Doping PS with CTAB resulted in mixed micelle formation at all stoichiometries and conditions investigated; employing selectively deuterated PS, a monotonic variation in scattering length density and dimensions of the micellar core and shell is observed for all contrasts. The concentration- and irradiance-dependence of the E to Z configurational transition was established in both neat and mixed micelles. A liposome dye release assay establishes the enhanced efficacy of photosurfactants at membrane disruption, with E-PS exhibiting a 4-fold and Z-PS a 10-fold increase in fluorescence signal with respect to pure CTAB. Our findings pave the way for external triggering and modulation of the wide range of CTAB-based biomedical and material applications.

Self-Assembly and Micellar Transition in CTAB Solutions Triggered by 1-Octanol.

This study exploits higher-order micellar transition ranging from ellipsoidal to rodlike to wormlike induced by 1-octanol (C8OH) in an aqueous solution of cetyltrimethylammonium bromide (CTAB), characterizing phase behavior, rheology, and small-angle neutron scattering (SANS). The phase diagram for the ternary system CTAB-C8OH-water was constructed, which depicted the varied solution behavior. Such performance was further inferred from the rheology study (oscillatory-shear frequency sweep (ω) and viscosity (η)) that displayed an interesting solution behavior of CTAB solutions as a function of C8OH. It was observed that at low C8OH concentrations, the solutions appeared viscous/viscoelastic fluids that changed to an elastic gel with an infinite relaxation time at higher concentrations of C8OH, thereby confirming the existence of distinct micelle morphologies. Small-angle neutron scattering (SANS) provided various micellar parameters such as aggregation numbers (Nagg) and micellar size/shape. The experimental results were further validated with a computational simulation approach. The molecular dynamic (MD) study offered an insight into the molecular interactions and aggregation behavior through different analyses, including radial distribution function (RDF), radius of gyration (Rg), and solvent-accessible surface area (SASA).

A portable digital optical kanamycin sensor developed by surface-anchored liquid crystal droplets

There is an increase in demand to develop simple, convenient, and low-cost approaches for rapid and label-free detection of antibiotics. Herein, we propose a new principle for the detection of kanamycin using the surface-anchored liquid crystal (LC) droplets. The optical images of the LC droplets uniformly change from four-clover, uniformly dark, and dark cross appearance gradually with the increase of surfactant concentration. The detection of kanamycin is fulfilled with the aid of a cationic surfactant cetyltrimethylammonium bromide (CTAB) and a kanamycin aptamer. The LC droplets show uniformly dark appearance and four-clover appearance in the presence of the aqueous solutions of CTAB and CTAB/aptamer complex, respectively. However, the specific binding of kanamycin to its aptamer can release the CTAB, which induces the uniformly dark appearance of the LC droplets. A portable device is built to measure the optical luminance of the LC droplets. This system can detect kanamycin with a concentration below 0.1 ng/mL (~0.17 nM) and also allows the detection of kanamycin in real samples such as milk and honey. Therefore, it is very promising in the development of new types of LC-based sensors by the surface-anchored LC droplets assisted with a portable optical device.

Interfacial Behavior of Aqueous Solutions of Cetyltrimethylammonium Bromide (CTAB), Additives and Their Mixtures: The Experimental and Modeling Study

In the present investigation, firstly, the surface tension measurements were conducted for aqueous solutions of cetyltrimethylammonium bromide, acetonitrile, and tetrahydrofuran by using a pendant drop apparatus at the temperature of 298.15 K and ambient pressure. Then a thermodynamic model was used and successfully reproduced the surface tension values. The percent of the average absolute deviation for surface tension was 0.667. The surface tensions of mixed aqueous solutions of (cetyltrimethylammonium+additives) were measured at various concentrations. Then, the values of critical micelle concentrations were measured based on surface tension and conductivity. The percent of the average absolute deviation of the thermodynamic model was 5.05, proving that the model successfully predicts the surface tension for aqueous mixed solutions of (cetyltrimethylammonium+additives). The presence of additives decreases the surface coverage of cetyltrimethylammonium and increases the critical micelle concentration values.

Pyrene Associates As a New Highly Sensitive Sensor for Monitoring the Content of Silver Nanoparticles in Aqueous Media

A study is performed of the luminescence of pyrene molecules solubilized in a supramolecular ordered structure formed as a result of the self-organization of molecules of cationic surfactant cetyltrimethylammonium bromide (CTAB) in the presence of trace amounts of aggregated silver nanoparticles (NPs). The study is performed using dilute aqueous solutions of CTAB and at CTAB concentrations that exceed the critical micelle concentration. The formation of a number of pyrene associates (high-energy excimers) that glow in the short-wavelength region of the optical spectrum is observed, relative to the glow of a low-energy dimer (470 nm), and the intensity of the glow of the resulting associates depends on the concentration of silver aquasol introduced into the considered solution. The phenomenon is explained by the location of pyrene molecules near the surfaces of aggregated silver nanoparticles, which have high-density electromagnetic fields caused by surface plasmon resonance. It is found that pyrene associates can be used as sensors for determining trace amounts of silver NPs in aqueous media.

Effect of antidiabetic metformin hydrochloride on physicochemical properties of cationic surfactant cetyltrimethylammonium bromide in aqueous solutions

In view of understanding the nature of molecular interactions between surfactant and drug, here we report the experimental conductance (κ), densities (ρ) and ultrasonic velocities (u) of cationic surfactant cetyltrimethylammonium bromide, CTAB (0.5−11 mM) in 2.0 mM aqueous solution of antidiabetic drug metformin hydrochloride as a solvent at different temperatures (303.15, 308.15, 313.15 K). The critical micelle concentration, cmc of CTAB in aqueous solution containing drug was determined from conductance and surface tension study at 298.15, 303.15, 308.15, and 313.15 K. From the experimental density and ultrasonic velocity data, properties such as apparent molar volume (V2,ϕ), isentropic compressibility (κS), apparent molar isentropic compressibility (κS,2,ϕ), specific acoustic impedance (Z), relative association (RA) were calculated and interpreted in terms of drug-surfactant interactions and effect of electrolyte drug on micellization of surfactant. Structural changes in studied solution due to presence of organic drug and temperature have been investigated. The thermodynamic properties of micellization like values of ΔGm0, ΔHm0, and ΔSm0 were calculated. The thermodynamics of micellization has been found to be spontaneous, exothermic and entropy driven process.

Study of volumetric, viscometric, and aggregation properties of losartan potassium and its interaction with amino acids and cetyltrimethylammonium bromide in aqueous solution

AbstractThis manuscript reports volumetric, viscometric, and aggregation properties of losartan potassium (LP) in aqueous medium and its interaction with a cationic surfactant (cetyltrimethylammonium bromide [CTAB]). Densities of drug solutions were used to calculate apparent molar volumes while constants of Jones–Dole equation were calculated from viscosity measurements. By measuring surface tension, refractive index, and electrical conductivity of drug solutions, critical micelle concentration (CMC) of drug was determined, and calculation of surface excess concentration, free energy change of adsorption, free energy change, entropy change, and enthalpy change of micellization was carried out. UV/Visible spectroscopic data were used to get an understanding about the interaction of drug with cationic surfactant (CTAB). This interaction gives an idea about the interaction of drug with biomembrane as micelles of surfactant are similar to membranes in structure. The data were also used to calculate different important parameters for drug–surfactant interaction such as partition coefficient and binding constant. Moreover, two amino acids (glycine and l‐tryptophan) were used in solutions of drug separately to change its CMC. The results from volumetric and viscometric studies showed that the presence of drug in solution resulted in more organization of solvent molecules due to hydrophobic interaction. From the values of ∆G°ads and ∆G°m, it was concluded that the adsorption of drug molecules at solution–air interface and formation of micelles occurred spontaneously. A strong drug‐surfactant (LP–CTAB) interaction was observed by the attachment of drug molecules onto micellar surface of surfactant. The presence of amino acids in the solution of drug caused a decrease in the CMC of LP.

Vitamin C stabilized in lysozyme and CTAB aqueous solutions

Vitamin C (VC) is an antioxidant and assists in treating cancer, but it hydrolyses and degrades in aqueous solutions due to oxidation and loses drug efficiency. It is critical to improve the stability of VC. Lysozyme (LYS) is a global protein and an enzyme, which is used as a model protein to probe the interactions of VC and protein relevant to VC degradation. Micellar solutions, formed by cationic surfactant cetyltrimethylammonium bromide (CTAB) and water, act as micro-reactors to stabilize VC. UV–vis and fluorescence spectroscopic methods are applied to investigate the interactions that control the properties of the VC-LYS-CTAB ternary model system, including kinetics of VC degradation and conformation changes of LYS (unfolding and recovery). The results suggest that LYS stabilizes VC by forming a complex and LYS partially unfolds, and CTAB micelles can slow down the rate of VC degradation. VC is the most stable in the VC- LYS-CTAB ternary system among VC-LYS, VC-CTAB aqueous solutions, and pure water. The strength of interactions decreases in the order of: VC degradation, interaction of CTAB micelles and VC, interaction of LYS and VC, and the weak hydrophobic interaction between CTAB and LYS. The former two are the major factors that control the alleviation of VC degradation and the recovery of LYS conformation. This work provides fundamental insights for drug stability and delivery, and personal product field where vitamins, proteins and surfactants are used.

Efficiently removing cetyl trimethyl ammonium bromide from wastewater by graphene oxide

Cetyl trimethyl ammonium bromide (CTAB) containing wastewater from dressing plant may pose a detrimental threaten to mineral beneficiation and environment. The adsorption of CTAB in aqueous solutions by graphene oxide (GO) has been studied in this work. X‐ray diffraction, X‐ray photoelectron spectroscopy, Fourier‐transform infrared spectrometer, and atomic force spectroscopy were used to characterize GO. The results indicated that the adsorption followed the Freundlich model could be well described by pseudo‐second order kinetic model. The adsorption capacity was much bigger than activated carbon and many natural clay minerals. The adsorption process was endothermic, and the adsorption mechanism of CTAB onto GO was proven to be controlled by surface complexation, hydrogen bonding, and electrostatic attraction.

Cooking oil-surfactant emulsion in water for harvesting Chlorella vulgaris by sedimentation or flotation

In this study, a novel harvesting emulsion (HEM) consisting of cooking oil in an aqueous solution of cetyltrimethylammonium bromide (CTAB) was tested for the harvesting of a technologically important microalga, Chlorella vulgaris. The influence of HEM dose, biomass and bovine serum albumin (BSA) (model interferer compound) on harvesting efficiency (E) were studied. The HEM E was over 90% at pH 10 (0.33% (v/v) cooking oil, 6.7 mg/L of CTAB) and 12 (0.13% (v/v) cooking oil, 2.7 mg/L of CTAB). Harvesting efficiencies at pH 4 and 7 were < 73.5% due to the absence of precipitate formation. Bovine serum albumin (10 mg/L) increased the HEM dose necessary to achieve E ˃ 90% by 1.2 (pH 10), and 3 fold (pH 12). By manipulating the dose of HEM and pH, the method of harvesting (flocculation/sedimentation or flotation) was adjustable depending on the technological requirements.

Hysteresis of conductivity in a micellar surfactant solution near the Krafft point

The specific conductivity of aqueous cetyltrimethylammonium bromide solutions has been investigated below and above the critical micelle concentration, in order to elucidate slow structural changes. Around the Krafft temperature (?25?C) the monomer solubility reaches the critical micelle concentration, and a significant increase in charge transport is recorded. When a temperature decreases, the micellar surfactant solution passes through the Krafft temperature, and a hysteresis phenomenon is observed with the appearance of crystals in a solution. We have scrutinized the conditions leading to this hysteresis and quantified some of the relevant parameters. We also outline a simple procedure that allows the ?erasure? of such structural memory effects, which are potentially detrimental to the formation of adsorbed self-assembled monolayers from solution.

A comparative study on the effects of Fe3O4 nanofluid, SDS and CTAB aqueous solutions on the CO2 hydrate formation

In this study, the effects of water-based Fe3O4 nanofluids containing 400 ppm sodium dodecyl sulfate (SDS) and 400 ppm cetyltrimethylammonium bromide (CTAB) in different concentrations of nanoparticles (0.05 wt%, 0.09 wt%, 0.15 wt%, 0.20 wt% and 0.25 wt%) on the kinetic parameters of carbon dioxide hydrate formation have been investigated and the results are compared with other aqueous solutions including pure water, aqueous solution of 400 ppm SDS, aqueous solution of 400 ppm CTAB and suspension of 0.15 wt% Fe3O4 nanoparticles. The kinetic parameters studied in this work included the mole of gas consumption, induction time and apparent rate constant. The experiments were performed at the initial pressure of 2.5 MPa and two temperatures of 274.15 K and 276.15 K. The experimental results showed that by increasing the concentration of nanoparticles up to 0.15% by weight, the effect of nanoparticles on the carbon dioxide hydrate formation increases. However, a further increase in nanoparticle concentration will reduce this effect. It was observed that the effect of the suspension of 0.15 wt% Fe3O4 nanoparticle on the carbon dioxide hydrate formation is more than the 400 ppm CTAB aqueous solution and less than the 400 ppm SDS aqueous solution. Results also showed that among different aqueous solutions, Fe3O4 nanofluid containing SDS with a concentration of 0.15 wt% nanoparticle is the best aqueous solution for carbon dioxide hydrate formation. In this nanofluid at 274.15 K, the induction time decreased by 70.6% and the mole of gas consumption and the apparent rate constant increased about 160% and 120.5%, respectively compared to pure water.

Visible light-driven flower-like Bi/BiOClxBr(1−x) heterojunction with excellent photocatalytic performance

In this work, a series of flower-like Bi/BiOClxBr(1−x) heterojunction photocatalysts have been developed. Bi nanoparticles were grown on the BiOClxBr(1−x) nanosheets via an in situ chemical reduction with the assistance of cetyltrimethylammonium chloride and cetyltrimethylammonium bromide aqueous solution. The in situ growth of Bi nanoparticles on the BiOClxBr(1−x) nanosheets could not only give rise to the optical absorption in the visible region, but also promote the photocatalytic performance of BiOClxBr(1−x). Bi/BiOCl0.8Br0.2 exhibited the highest photocatalytic performance, which could completely degrade RhB in 12 min under the UV light irradiation and 6 min under visible light irradiation, respectively. Moreover, holes and superoxide radicals were verified to be the primarily active species in the photocatalytic process.

Gram-Scale Synthesis of Isolated Monodisperse Gold Nanorods.

Although gold nanorods (AuNRs) have strong potential applications in nanotechnology, plasmonics, and sensing, the scale-up synthesis of isolated AuNRs in gram quantities remains a challenge. Nearly all previously reported methods produce aqueous solutions of cetyltrimethylammonium bromide (CTAB)-coated AuNRs in milligram quantities with yields of approximately 20-30 % in terms of AuI to Au0 conversion. In addition, it is difficult to remove the CTAB bilayer from the surface of AuNRs and yet make them soluble and functionalized for further processing and chemical modification. This report describes the synthesis of monodisperse functionalized AuNRs (standard deviation, σ≈5 %) in gram quantities. Our approach involved increasing the concentration of HAuCl4 ⋅3 H2 O in the growth solution to produce larger quantities of starting AuNRs and further reducing the remaining AuI ions onto the surface of AuNRs. The slow and controlled addition of ascorbic acid as a reducing agent continued the conversion of AuI into Au0 (through a disproportionation reaction) onto the surface of the nanorods, which maintained their uniform morphology without creating any unwanted impurities of various shapes. In addition, this approach significantly narrowed the size distribution owing to continuous growth of the partially grown AuNRs during the initial stage of the synthesis. To isolate a 1 g quantity of the AuNRs and to make them functionalized for further chemical reactions, a ligand-exchange approach was utilized, in which the CTAB surfactant was replaced with 4-mercaptophenol. The thiol group from 4-mercaptophenol formed a covalent bond with the surface of the AuNRs, leaving free functional OH groups available for further chemical coupling reactions. For the ligand-exchange process, a concentrated solution of 4-mercaptophenol in tetrahydrofuran solution was introduced into the AuNRs solution. Pure AuNRs functionalized with 4-mercaptophenol were isolated by dispersion and rinsing with an excess amount of THF, followed by centrifugation.

Temperature dependent solution properties of amino acids in colloidal solutions

Volumetric and acoustic studies of amino acids (l‑aspartic acid and l‑serine) in water and in aqueous cetyl trimethyl ammonium bromide (CTAB) solutions were carried out to understand intermolecular interactions in aqueous solutions of amino acids and in colloidal solutions containing cationic micelles. Density and sound velocity of amino acids solutions of different concentrations in water and in colloidal solutions of CTAB were measured at different temperatures (303.15 K–313.15 K). Volumetric and acoustic parameters like apparent and partial molar volume (Vφ and Vφo), expansibility factor (Eφo), transfer volume, compressibility factors (Kφ and Kφo) and intermolecular free length (Lf) were calculated using measured density and sound velocity data of amino acids solutions. Positive values of Vφ and negative values of Kφ are indicative of strong intermolecular electrostatic interactions among ions of amino acids and water molecules. Presence of CTAB molecules in micellar form in amino acids solutions causes an overall increase in the degree of intermolecular interactions among components of solutions. Moreover, positive values of expansibility factor showed the structure making behavior of amino acids both in water and in aqueous CTAB solutions.

Effect of Preliminary Binding of HAuCl4 with DNA and Cetyltrimethylammonium Bromide in Aqueous Solution on Morphology of the Formed Nanoparticles

Competitive interactions in the HAuCl4–DNA–cationic surfactant (cetyltrimethylammonium bromide) systems have been studied. Decisive role of the components binding on size and shape of gold nanoparticles obtained via reduction in these mixtures has been shown.