Solutions Of Cetyltrimethylammonium Bromide Research Articles

Effects of Sodium Bromide Salt and Temperature on the behaviour of Aqueous Solution of Cetyltrimethylammonium Bromide

The effects of sodium bromide(NaBr) salt and temperature on the aggregation behaviour of cetyltrimethylammonium bromide (CTAB) have been studied using conductivity data.Conductivity was observed to vary increasingly with both temperature and salt concentration. The critical micelle concentration (CMC) of CTAB decreased with increase in the concentration of NaBr but increased as temperature increased. For example,the CMCs of CTAB in 0.0 and 10.0mM solutionsof NaBr at 30 °C were 1.68 and 1.50 mMrespectively while those of the same concentrations at 35 °C were 1.84 and 1.63respectively.It wasalso found that both salt and temperature influenced the degree of micelle ionization as well as the free energy of micellization. Results also showedthat the stability of CTAB micelles was enhanced by adding NaBr molecules.These observations have been discussedin terms of the electrostatic repulsion of charged CTAB head group.

Measuring contact angle and meniscus shape with a reflected laser beam

Side-view imaging of the contact angle between an extended planar solid surface and a liquid is problematic. Even when aligning the view perfectly parallel to the contact line, focusing one point of the contact line is not possible. We describe a new measurement technique for determining contact angles with the reflection of a widened laser sheet on a moving contact line. We verified this new technique measuring the contact angle on a cylinder, rotating partially immersed in a liquid. A laser sheet is inclined under an angle φ to the unperturbed liquid surface and is reflected off the meniscus. Collected on a screen, the reflection image contains information to determine the contact angle. When dividing the laser sheet into an array of laser rays by placing a mesh into the beam path, the shape of the meniscus can be reconstructed from the reflection image. We verified the method by measuring the receding contact angle versus speed for aqueous cetyltrimethyl ammonium bromide solutions on a smooth hydrophobized as well as on a rough polystyrene surface.

Protonation equilibria of L-phenylalanine and maleic acid in cationic micellar media

Solute-solvent interactions of L-phenylalanine and maleic acid have been studied in various concentrations (0.5-2.5% w/v) of cetyltrimethylammonium bromide solution maintaining an ionic strength of 0.16 mol dm-3 at 303 K. The protonation constants have been calculated using the computer program MINIQUAD75 and the best fit models are arrived at based on statistical grounds employing crystallographic R factor, x2, skewness and kurtosis. These protonation constants values have been found to shift in micellar media as compared to those in pure water. The differences in the values have been attributed to the solvent properties of the interfacial and bulk phases involving contribution from the micellar surface potential in the case of charged micelles. The trend of log values of step-wise protonation constants with mole fraction of the medium have been explained based on electrostatic and non-electrostatic forces operating on the protonation equilibria. Distributions of species, protonation equilibria and effect of influential parameters on the protonation constants have also been presented.

Rheological Behavior of Viscoelastic Wormlike Micelles in CTAB/SSS/H2O Systems

The effect of the addition of sodium 4-styrenesulfonate (SSS) and KNO3 as well as temperature and shear rate on the structural transition of aqueous micellar solutions of the cationic surfactant cetyl trimethyl ammonium bromide (CTAB) was studied by viscosity. The effect of hydrocarbons on viscoelastic CTAB solutions was also examined. Possible mechanism for formation of CTAB wormlike micelles in the presence of sodium 4-styrenesulfonate (SSS) and KNO3 was discussed. The rapid increase in the apparent viscosity of CTAB solutions on the addition of SSS and KNO3 was due to the transition in micellar shape from spheres to wormlike ones. The rheological properties of CTAB solutions fit Maxwell model at low shear frequency. AFM image indicated a structure of transient network of CTAB/SSS/KNO3/H2O solution.

Electric field driven assembly of hybrid micelles for shaping of porous silica films

The technological impact of porous structures in catalytic applications has stepped up the search for innovative shaping tools. A new approach to shape porous structures based on the assembly of hybrid micelles under the influence of a directional driving force, such as the electric field, is proposed in this work. The growth of silica porous coatings induced by electrophoresis has been explored. The electrophoretic deposition (EPD) of different cetyltrimethylammonium bromide (CTAB) solutions, a silica sol (SiO2) and a hybrid sol (CTAB+SiO2) has been studied in terms of the solution/sol conductivity, the electrophoretic mobility of the suspended species and the applied electric field and time. After the optimisation of the sol composition for EPD, the growth behaviour of the deposit has been determined by atomic force microscopy. Results evidence the assembly of hybrid micelles as a consequence of the synergism of two phenomena: the increase in the concentration of the micelles at the substrate surroundings and the silica sol gelling. Crack free silica porous films (0·4 mg cm−2) with a deposited mass per unit area one order of magnitude higher than those prepared by dip coating can be produced by EPD.

Superoleophobic Textured Copper Surfaces Fabricated by Chemical Etching/Oxidation and Surface Fluorination

We report a convenient route to fabricate superoleophobic surfaces (abridged as SOS) on copper substrate by combining a two-step surface texturing process (first, the substrate is immersed in an aqueous solution of HNO3 and cetyltrimethyl ammonium bromide, and then in an aqueous solution of NaOH and (NH4)2S2O8) and succeeding surface fluorination with 1H,1H,2H,2H-perfluorodecanethiol (PFDT) or 1-decanethiol. The surface morphologies and compositions were characterized by field emission scanning electron microscopy and X-ray diffraction, respectively. The results showed that spherical micro-pits (SMP) with diameter of 50-100 μm were formed in the first step of surface texturing; in the second step, Cu(OH)2 or/and CuO with structures of nanorods/microflowers/microballs were formed thereon. The surface wettability was further assessed by optical contact angle meter by using water (surface tension of 72.1 mN m(-1) at 20°C), rapeseed oil (35.7 mN m(-1) at 20°C), and hexadecane (25.7 mN m(-1) at 20°C) as probe liquids. The results showed that, as the surface tension decreasing, stricter choosing of surface structures and surface chemistry are required to obtain SOS. Specifically, for hexadecane, which records the lowest surface tension, the ideal surface structures are a combination of densely distributed SMP and nanorods, and the surface chemistry should be tuned by grafted with low-surface-energy molecules of PFDT. Moreover, the stability of the so-fabricated sample was tested and the results showed that, under the testing conditions, superhydrophobicity and superoleophobicity may be deteriorated after wear/humidity resistance test. Such deterioration may be due to the loss of outermost PFDT layer or/and the destruction of the above-mentioned ideal surface structures. For UV and oxidation resistance, the sample remained stable for a period of 10 days.

Effect of Preparation Conditions on the Performance of Ni-TiB<sub>2</sub>-Gd<sub>2</sub>O<sub>3</sub> Composite Coatings

TiB2and Gd2O3were used as codeposited particles for the first time in preparing Ni-TiB2-Gd2O3composite coatings to improve its performance. Ni-TiB2-Gd2O3composite coatings were prepared by electrodeposition method from a nickel cetyltrimethylammonium bromide and hexadecylpyridinium bromide solution containing TiB2and Gd2O3particles. The content of codeposited TiB2and Gd2O3in the composite coatings was controlled by the addition of different TiB2and Gd2O3particles concentrations in the solution, respectively. The effects of TiB2and Gd2O3content on microhardness, wear weight loss, and friction coefficient of composite coatings were investigated, respectively. Ni-TiB2-Gd2O3composite coatings shows higher microhardness and lower wear weight loss, friction coefficient than those of the pure Ni coating and Ni-TiB2composite coatings. The wear weight loss of Ni-TiB2-Gd2O3composite coatings is lower 9.13 and 1.59 times than that of the pure Ni coating and Ni-TiB2composite coatings, respectively. The friction coefficients of pure Ni coating, Ni-TiB2and Ni-TiB2-Gd2O3composite coatings are 0.723, 0.815 and 0.43, respectively. Ni-TiB2-Gd2O3composite coatings shows the least friction coefficient among the three coatings. Gd2O3particles in composite coatings serves as solid lubricant between contact surfaces, decreases the friction coefficient, abates the wear and increases the corrosion resistance of the composite coatings. The loading-bearing capacity and the wear-reducing effect of the Gd2O3particles in the composite coatings are closely related to the content of Gd2O3particles in the composite coatings.

Effect of copper doping on CoTiO3 ilmenite type nanoparticles for removal of congo red from aqueous solution

The CoxCu1−xTiO3 (x=1, 0.8, 0.5, 0.2, 0) nanoparticles have been prepared. Nanoparticles were prepared by calcination of precursor mixture of TiO2, Cu(OH)2 and Co(OH)2 in aqueous cetyltrimethyl ammonium bromide (CTAB) solution. The nanoparticles were characterized using X-ray powder diffraction (XRD), Fourier infrared spectroscopy (FTIR), Scanning electron microscope (SEM) and Brunauer–Emmett–Teller (BET). The CoxCu1−xTiO3 nanoparticles were used for removal of congo red (CR) from aqueous solutions. The effect of parameters such as contact time, pH and temperature on the adsorption of CR was investigated. Tow common kinetic models, pseudo-first-order and pseudo-second-order were employed to describe the adsorption kinetics. The adsorption of CR followed pseudo-first-order kinetic model. Thermodynamic results revealed that the adsorption of CR onto CoxCu1−xTiO3 particles is endothermic and spontaneously process. The nanoparticles of CoxCu1−xTiO3 can be conveniently regenerated by chemical and physical methods after adsorption. Two common isotherm models, the Langmuir and Freundlich were used to investigate the interaction of CR onto CoxCu1−xTiO3 nanoparticles. The equilibrium adsorption of CuTiO3 was best described by the Langmuir isotherm model. The reused sorbent can be employ after 5cycle. The results showed that the adsorption capacity of Ilmenite type nanoparticles for CR are as followed: CoTiO3<Co0.2 Cu0.8TiO3<Co0.5Cu0.5TiO3<Co0.8 Cu0.2TiO3<CuTiO3.

Research on the Micellar Dispersal Behaviors in Mixed Surfactant System by Cyclic Voltammetry

Cyclic voltammetry method was used to investigate the dispersal behaviors of micelles in mixed solutions of cationic surfactant CTAB (cetyltrimethyl ammonium bromide) and anionic surfactant SDS (sodium dodecyl sulfate) at 313 K using ferrocene as the probe. Voltammetric behaviors of ferrocene on the electrode were reversible, indicating the diffusion of ferrocene in the mixtures of cationic and anionic surfactants was controlled by the microstructures of the mixtures. The results showed that the anionic micellar diffusion coefficient initially decreased and then increased with CTAB content due to the structural transformation of micelles. However, the cationic micellar diffusion coefficient curve appeared a monotonous decreasing trend with the increase of the CTAB content in the experimental range, and the diffusion coefficient of cationic micelle was smaller than that of anionic micelle.

Preparation and Properties of Ni-TiB2-Gd2O3 Composite Coatings by Electrodepositon

Ni-TiB2-Gd2O3 composite coatings were prepared by electrodeposition method from a nickel cetyltrimethylammonium bromide and hexadecylpyridinium bromide solution containing TiB2 and Gd2O3 particles. The composite coatings were characterized with X-ray diffraction (XRD), atomic emission spectrometer (ICP-AES), scanning electron microcopy (SEM) and energy- dispersive analyses of X-ray (EDAX), respectively. That the codesposition of TiB2 and Gd2O3 into the coatings were demonstrated by XRD, EDAX, ICP-AES and SEM. TiB2 and Gd2O3 entered the lattice of Ni. The incorporation of TiB2 and Gd2O3 particles in the matrix can largely reduce the wear of the nickel composite coatings.

Synthesis of 3D micro- and nano-hierarchical structure InVO4 porous microspheres with improved visible-light photocatalytic activities

Three-dimensional (3D) hierarchical structure InVO4 porous microspheres were fabricated by a hydrothermal method with the assistance of cetyltrimethyl-ammonium bromide (CTAB). X-ray diffractometer, scanning electron microscopy, transmission electron microscopy, adsorption analyzer, diffuse refection spectroscopy, UV–Vis spectroscopy, and photoluminescence spectroscopy were adopted to analyze the structure–property relationship of samples, and the formation mechanism was also discussed. The results show that the concentration of CTAB solution has important influence on the grain size, crystal structure, and morphology of as-synthesized InVO4 samples, thus affecting the optical property and photocatalytic activity. When the concentration of CTAB solution is 1 wt%, we can obtain perfect 3D hierarchical porous microspheres. Such microspheres with diameter size about 2–5 μm are assembled by numerous nanocrystals, and exhibit an enhanced photocatalytic activity in the degradation of Rhodamine B under visible light irradiation. Moreover, Oswald ripening and self-assembly aggregation are presumed to play an important role in the formation of these 3D hierarchical structure InVO4 porous microspheres.

A wireless magnetoelastic sensor for uranyl using DNAzyme–graphene oxide and gold nanoparticles-based amplification

A wireless magnetoelastic sensor (WMS) for uranyl detection has been developed using DNAzyme–graphene oxide (GO) and gold nanoparticles (AuNPs)-based amplification. The WMS is fabricated by immobilizing a layer of GO film on a magnetoelastic ribbon-like sensor. When the substrate strand of DNAzyme was cleaved in the presence of UO22+, the single-stranded DNA (ssDNA) was adsorbed onto the GO film of the WMS, resulting in a decrease of resonance frequency of the WMS. HAuCl4 can be reduced by ascorbic acid (AA) to atom Au coated on AuNPs in cetyltrimethyl ammonium bromide (CTMAB) solution, leading to the signal amplification of the system. When the molar ratio of AA and HAuCl4 was 3:2, the response signals linearly correlated with the concentration of UO22+ over the range of 9.57×10−9 to 1.20×10−7M in the MES buffer solution of pH 5.0 with a detection limit of 2.87×10−9M. The proposed WMS has additional advantages of being less time-consuming, low cost and remote query, and avoids the interference of some metals such as Cu2+, Fe2+, Fe3+, Hg2+, and Tb3+. It has been successfully applied for detecting UO22+ in real samples with a satisfactory result. A polyacrylamide gel electrophoresis (PAGE) assay, scanning electron microscopy (SEM) and UV–vis spectra were used to confirm the mechanism for structure switching and signal amplification.

Graphene‐Like MoS2/Graphene Composites: Cationic Surfactant‐Assisted Hydrothermal Synthesis and Electrochemical Reversible Storage of Lithium

A cationic surfactant-assisted hydrothermal route is developed for the facile synthesis of graphene-like MoS2 /graphene (GL-MoS2 /G) composites based on the hydrothermal reduction of Na2 MoO4 and graphene oxide sheets with L-cysteine in the presence of cetyltrimethylammonium bromide (CTAB), following by annealling in N2 atmosphere. The GL-MoS2 /G composites are characterized by X-ray diffraction, electron microscopy, high-resolution transmission electron microscopy, and Raman spectroscopy. The effects of CTAB concentration on the microstructures and electrochemical performances of the composites for reversible Li(+) storage are investigated. It is found that the layer number of MoS2 sheets decreases with increasing CTAB concentration. The GL-MoS2 sheets in the composites are few-layer in the case of 0.01∼0.03 mol L(-1) CTAB of hydrothermal solution and single-layer in the case of 0.05 mol L(-1) CTAB. The GL-MoS2 /G composites prepared with 0.01-0.02 mol·L(-1) of CTAB solution exhibit a higher reversible capacity of 940-1020 mAh g(-1) , a greater cycle stability, and a higher rate capability than other samples. The exceptional electrochemical performance of GL-MoS2 /G composites for reversible Li(+) storage could be attributed to an effective integration of GL-MoS2 sheets and graphene that maximizes the synergistic interaction between them.

Impact of selected wastewater constituents on the removal of sulfonamide antibiotics via ultrafiltration and micellar enhanced ultrafiltration

To better understand the environmental mobility of sulfonamide antibiotics and develop improved processes for their removal during wastewater treatment, stirred cell ultrafiltration (UF) experiments were conducted using both synthetic and real wastewater effluent. The interactions between selected sulfonamides (sulfaguanidine, sulfathiazole and sulfamerazine), solids and dissolved organic matter were systematically explored. The further impact of micellar enhanced ultrafiltration (MEUF), a process in which surfactants are added at micellar concentrations to enhance removal of various trace contaminants from aqueous streams, was then explored by using a cationic surfactant, cetyltrimethylammonium bromide (CTAB). Ultrafiltration of sulfonamides in the absence of other materials generally removed only 15–20% of the antibiotics. The presence of micellar solutions of CTAB generally improved removal of sulfonamides over UF alone, with rejections ranging from 20 to 74%. Environmental solids (sediment) further increased retention of sulfonamides using both UF and MEUF, but the presence of DOM did not influence rejection. Similar trends were observed on UF and MEUF of real effluent samples that had been spiked with the sulfonamides, confirming the environmental relevance of the observed interactions between sulfonamides, surfactant, and wastewater constituents. The results demonstrate that MEUF processes can be designed for the selective removal of such trace contaminants as sulfonamide antibiotics.

Adhesion work and wettability of polytetrafluorethylene and poly(methyl methacrylate) by aqueous solutions of cetyltrimethylammonium bromide and Triton X-100 mixture with ethanol

The contact angle measurements of the aqueous solutions of p-(1,1,3,3-tetramethylbutyl)phenoxypoly(ethylene glycol) (TX-100) and cetyltrimethylammonium bromide (CTAB) mixture with ethanol on polytetrafluoroethylene (PTFE) and poly (methyl methacrylate) (PMMA) were carried out in the range of the total concentration of TX-100 and CTAB mixture from 1×10−6 to 1×10−3 M and in the whole range of ethanol concentration. In the surfactant mixture, the mole fraction of TX-100 was equal to 0.2; 0.4; 0.6 and 0.8, respectively. From the obtained results, the critical surface tension of PTFE and PMMA wetting and the adhesion work of the solutions to the polymer surface were established. The PMMA surface tension was calculated from the Neumann’s equation. It appeared that for the ethanol concentration higher than that corresponding to the association of its molecules, the surface tension of PMMA calculated from the Neumann’s equation is close to the critical surface tension of PMMA wetting. It also appeared that it is possible to predict the work of adhesion of the studied solutions to the PMMA surface by using the PMMA surface tension data determined on the basis of the van Oss et al. approach to the interfacial tension and those from the Neumann’s equation.

Denaturation of bovine serum albumin under the action of cetyltrimethylammonium bromide, according to data from fluorescence analysis

The tryptophan fluorescence of bovine serum albumin (BSA) in solutions with different concentrations of cationic detergent cetyltrimethylammonium bromide (CTAB) at different pH is investigated, providing information on BSA denaturation under the action of CTAB. It is found that BSA denaturation under the action of CTAB at all of the investigated pH values (3.5–8.0) is a single-stage process, as determined by BSA tryptophan fluorescence quenching, by an increased degree of the BSA tryptophan fluorescence polarization, and by the values of the parameters for the rotational diffusion of BSA molecules in CTAB solutions. It is shown that the cationic detergent CTAB is more efficient for BSA denaturation at pH values higher than the BSA isoelectric point (4.9).

CTAB aggregation in solutions of higher alcohols: Thermodynamic and spectroscopic studies

The effect of organic additive, C8–OH and C9–OH (octan-1-ol and nonan-1-ol) on the micellar behavior of aqueous solution of cetyltrimethylammonium bromide, CTAB was examined by thermodynamic (density and speed of sound) measurements. The polar compounds form the additive-CTAB mixed micelles which cause micellar growth. The critical micelle concentration, cmc, and degree of counterion dissociation, α, of aqueous solution of CTAB containing different amounts of monohydric alcohols have been determined at various temperatures by means of electrical conductivity. Fluorescence method has also been used to obtain cmc values as well as the aggregation number, Nagg, of CTAB in the presence of studied alcohols. In general, the experimental results indicate that micelle formation is hindered by a rise in temperature. In addition, alcohols show an inhibitory effect on the formation of micelles of CTAB. The results are well supported by spectral studies viz. fluorescence and NMR.

The role of small organic amine molecules and their aggregates in the crystallization of microporous materials

A series of 1,6-hexamethylenediamine (1,6-HDA) solutions with different concentrations were prepared and used as the structure directing agents for the crystallization of microporous materials. The surface tension of these solutions has been measured to inspect the assembly behavior of 1,6-HDA molecules. It has been found that the surface tension of these solutions decrease with the increase of 1,6-HDA concentration, which is similar to what in surfactant CTAB (Cetyl trimethyl ammonium bromide) solutions. When they were used to direct the crystallization of aluminophosphites, zincophosphates, and aluminophosphates, it was found that at low concentration, 1,6-HDA molecules cannot affect the crystallization process, and three-dimensional frameworks without 1,6-HDA in it were obtained. When 1,6-HDA concentration increased, the surface tension of these solution decreased sharply, and 1,6-HDA containing three-dimensional (3-D) frameworks were formed. 1,6-HDA molecules retained in these structure were not in assembling state, but in independent state. At high 1,6-HDA concentration, the surface tension of the solutions changed slowly accompanying with the assembly of 1,6-HDA molecules. It always resulted in the formation of layered structures with the inorganic layers interleaved by composite layers of diprotonated 1,6-HDA. Formation of large-micropore containing 3-D frameworks mainly resulted from the interaction between inorganic framework and organic amine at proper ratio, not from the assembly of 1,6-HDA molecules. Otherwise, the aggregates of 1,6-HDA molecules favors the formation of layered materials.

An instantaneous and highly selective chromofluorogenic chemodosimeter for fluoride anion detection in pure water.

The development of chromofluorogenic sensors for anions is a well-established and studied field in the supramolecular chemistry realm.1 This is due to the important roles of anions in biological processes, deleterious effects (such as environmental pollutants), and as toxic compounds and carcinogenic species.2

Magnetic resonance imaging of reaction-driven viscous fingering in a packed bed

The formation of 3-dimensional viscous fingers has been investigated in a packed bed using magnetic resonance imaging. Fingering patterns are produced as a result of the formation of a highly viscous wormlike micelle solution formed at the interface between solutions of cetyltrimethylammonium bromide (CTAB) and sodium salicylate (NaSal), which have similar viscosities, but that are significantly lower to the wormlike micelle solution. In this system, fingers are driven by an interfacial instability, rather than a Saffman–Taylor instability. The structure of the fingering patterns, which were found to be sensitive to flow rate, where analysed using histogram plots characterizing the distribution of pores containing the CTAB solution. This system shares similar characteristics to the growth of biofilms.