Effect Of Cetyltrimethylammonium Bromide Concentration Research Articles

Effect of cetyltrimethyl‐ammonium bromide on the properties of hydroxyapatite nanoparticles stabilized Pickering emulsion and its cured poly(L‐lactic acid) materials

Hydroxyapatite (HAp) nanoparticles stabilized Pickering emulsions were prepared by dichloromethane (CH2 Cl2 ) dissolved poly(L-lactic acid) (PLLA) as the oil phase and the deionized water with different concentrations of cetyltrimethyl-ammonium bromide (CTAB) as the aqueous phase. Effect of CTAB concentration on emulsions type and stability were studied. The emulsion type underwent a two-phase inversion, and emulsion stability increased first and then decreased with increasing CTAB concentrations. Besides, effect of CTAB concentration on zeta potential, aggregate size, contact angle of HAp nanoparticles and the oil-water interfacial tension were studied. The results indicated that zeta potential value of HAp nanoparticles changed from negative to positive, and the contact angle increased to over 80° initially and then decreased to below 40° rapidly. The distribution of HAp nanoparticles on the surface of emulsion droplets with different concentrations of CTAB (5 and 20 mM) was characterized using laser-induced confocal microscope. It revealed the distribution of HAp nanoparticles changed with different CTAB concentrations. The cured PLLA materials were obtained after the solvent being volatilized using as-received emulsions as templates. Scanning electron microscope images showed both microspheres and porous materials with interconnected pore structure were obtained. In conclusion, the microstructure of microspheres or porous PLLA materials is controllable by adjusting the property of HAp nanoparticles stabilized Pickering emulsions with appropriate amount of CTAB.

Ceria nanorod supported gold nanoparticles as structured catalysts for the oxidative steam reforming of methanol: Effect of CTAB concentration on physiochemical properties and catalyst performance

Ceria (CeO2) supports were synthesized by hydrothermal treatment with different Cetyltrimethylammonium bromide (CTAB) concentrations (CeO2-X: 0.135, 0.270, 0.540 and 1.080, where X is the CTAB concentration in mmol). The micro-structures of bundle-like ceria nanorods (NR) were produced by thermal treatment of the crystalline Ce(OH)CO3 precursor. The exposed crystal planes of (200) and (111), corresponding to the d-spacing of 0.27 and 0.31 nm, were confirmed by high resolution-transmission electron microscopy (HR-TEM). The fundamental characteristics of CeO2-0.135 led to the highest surface area, surface area normalized reducibility and oxidized gold species (Aun+/Au0) on the surface, relatively higher oxygen vacancies and a smaller average gold particle size (7.9 nm). The activity results show that the Au/CeO2-0.135 has the highest methanol conversion and H2 production rate for oxidative steam reforming of methanol (OSRM). The reducibility and gold particle size played a crucial role in determining the H2/CO2 ratio at the temperature of 200 °C.

Truncated Triangular Silver Nanoparticles using low concentration of CTAB

Triangular silver nanoparticles have special properties which increase their importance in chemistry, biology, physical and medical applications. This work concerns with fabrication of truncated nanotriangles, using a simple chemical method. The seed mediated growth method that is usually used to synthesize nanorods, is modified to create nanotriangles. By using this modified method, we successfully obtained silver truncated nanotriangles by adding low concentration of cetyltrimethylammonium bromide (CTAB) into seed solution. UV-visible spectroscopy (UV-Vis) was used to characterize the surface plasmon resonance of the formed nanoparticles. Also, the geometrical properties of nanoparticles were characterized by transmission electron microscopy (TEM) and scanning tunneling microscopy (STM). The average edge length of truncated nanotriangle is affected by varying the amount of seed added to the growth solution; it varies from 56 nm up to 75 nm according to the amount of seed used. The degree of truncation (T) for the produced nanotriangle edges has been estimated. Furthermore, the effect of CTAB concentration as well as the speed in which NaBH4 is added to the seed solution on the formed nanoparticles was investigated.

A flexible silica aerogel with good thermal and acoustic insulation prepared via water solvent system

In this paper, transparent flexible hydrophobic silica aerogels were prepared by replacing the traditional alcohol solvent with water, using methyltriethoxysilane (MTES) and cetyltrimethylammonium bromide (CTAB), via acid-base two steps method and CO2 supercritical drying. The role of surfactant CTAB in the gel–sol process was revealed, and the effect of CTAB concentration on the gel structure was analyzed. With the concentration increasing, the skeleton structure of the gel gradually changed from coarse graininess to continuous fiber. The obtained aerogels showed good elastic properties. With the increasing of density, the elastic modulus of aerogels gradually increased, so that the length could be restored to 63% of the original length after 50% compression strain. Aerogels also had low thermal conductivity and good thermal stability. The thermal conductivity at room temperature was only 0.0215 W/(m·K) and the initial decomposition temperature was up to 511 °C. For the aerogel with thickness of 11.8 mm and density of 60 mg/cm3, it showed good sound absorption and sound insulation properties. When the sound frequency was 2000 Hz, the sound absorption coefficient was 0.91, and the sound transmission loss between 500 and 1600 Hz was 13–21 dB. This work provides a facile approach to fabricate lightweight and flexible silica aerogels for thermal and acoustic insulation applications.

Wet-chemical preparation of TiO2-nanostructures using different solvents: Effect of CTAB concentration and tentative mechanism of particle formation

In this paper, TiO2 nanostructures (TiO2-NSs) were synthesized in a controlled way. The effects of the use of a surfactant, Cetyl trimethylammonium bromide (CTAB), and the nature of the solvent of synthesis (ethanol and toluene) on the characteristics of the final product were studied. For this, TiO2-NSs were characterized using IR spectroscopy, X-ray diffraction (XRD), Transmission and Scanning Electron Microscopy. The solid obtained, without heat treatment, presented an amorphous structure that crystallized when treated at 450 °C, giving anatase as crystalline phase, independent of the solvent of synthesis and the concentration of CTAB used. The size of the crystallite in the powders synthesized was 3–5 nm and was reduced on increasing CTAB concentration, regardless of the solvent used. Using ethanol, the primary particles had a spheroidal or needle type shape of nanometric size (<100 nm) and the agglomerates were spherical (1–5 μm), reducing in size on the addition of CTAB. On using toluene, irregular-shaped aggregates with acute edges were formed (10–20 μm), made up of primary particles nanometric (<100 nm) and with the presence of poros. Given the nature of the synthesis process, a mechanism was proposed to explain the formation of the TiO2-NSs.

Effect of CTAB concentration on the properties of graphene nanosheet produced by laser ablation

Effects of the concentration of cetyltrimethylammonium bromide (CTAB) on the properties of graphene nanosheets produced by laser ablation method in CTAB medium have been studied experimentally. The beam of a Q-switched Nd:YAG laser of 1064nm wavelength at 7ns pulse width with 1.5J/cm2 fluence was employed to irradiate the graphite target in different concentration of CTAB. Produced graphene nanosheets were diagnosed by UV–Vis–NIR spectroscopy, FTIR spectrum, X-ray diffraction pattern, transmission electron microscopy, field emission scanning electron microscopy, Raman scattering spectrum and X-ray photoelectron spectroscopy. Results show that CTAB is a very capable ablation medium for producing graphene and there is a critical concentration of CTAB for producing few layers graphene nanosheets.

Effect of cetyl trimethyl ammonium bromide concentration on structure, morphology and carbon dioxide adsorption capacity of calcium hydroxide based sorbents

Calcium hydroxide (Ca(OH)2) has been proposed as an important material for industrial, architectural, and environmental applications. In this study, calcium acetate was used as a precursor and cetyl trimethyl ammonium bromide (CTAB) was used as a surfactant to synthesize Ca(OH)2 based adsorbents for carbon dioxide (CO2) capture. The effect of CTAB concentration (0.2–0.8M) on the structure, morphology and CO2 adsorption performance of Ca(OH)2 was studied in detail. The synthesized samples were characterized by X-ray diffraction (XRD), Fourier transform infrared (FTIR) spectroscopy, field emission scanning electron microscopy (FESEM), BET surfaced area and thermogravimetry-differential thermal analysis (TG–DTA) techniques. The phase purity, crystallite size, Brunauer–Emmett–Teller (BET) surface area and CO2 adsorption performance of Ca(OH)2 precursor adsorbents were significantly increased when the concentration of CTAB was increased. XRD results showed that pure Ca(OH)2 phase was obtained at the CTAB concentration of 0.8M. TGA results exhibited that 0.8M of CTAB-assisted Ca(OH)2 precursor adsorbent possessed a residual carbonation conversion of ∼56% after 10 cycles.

Effect of CTAB Concentration on Synthesis and Sensing Properties of Perovskite Oxide via a Hydrothermal Process

La0.7Sr0.3FeO3 materials with morphologies including nanoparticles, nanorods and nanowires were synthesized via a hydrothermal process assisted with different cetyltrimethyl ammonium bromide (CTAB) concentration. XRD, SEM and BET were used to characterize the morphology, composition and structural properties of the nanomaterials. The effect of CTAB concentration on morphology and growth mechanism of La0.7Sr0.3FeO3 was discussed. The gas sensing properties of La0.7Sr0.3FeO3 materials with different morphologies were also carried out in 0.1~ 100 ppm formaldehyde.

C60-functionalized MWCNT based sensor for sensitive detection of endocrine disruptor vinclozolin in solubilized system and wastewater

a b s t r a c t A novel fullerene (C60) functionalized multi-walled carbon nanotubes (MWCNTs) fabricated electrochemical sensor was developed for the sensitive determination of the endocrine disruptor vinclozolin in a solubilized system of cetyltrimethyl ammonium bromide (CTAB). The home-made sensor was characterized by scanning electron microscopy and electrochemical impedance spectroscopy. It was found that the nanocomposite film of C60–MWCNTs on GCE exhibits electrocatalytic activity towards vinclozolin reduction and also lowers the reduction overpotential. The influence of the optimization parameters such as pH, effect of CTAB concentration and effect of loading of composite mixture of C60 and MWCNTs on the analytical performance of the sensor was evaluated. Various kinetic parameters such as electron transfer number (n), proton transfer number (m), charge transfer coefficient (˛) and diffusion coefficient (D) were also calculated. Under optimized conditions, the squarewave reduction peak current was linear over the concentration range of 2.54–8.75 M with the detection and quantification limit of 0.091 M and 0.3 M respectively. The fabricated sensor was successfully applied to the detection of vinclozolin

CHARACTERIZING EFFECTS OF CATIONIC SURFACTANT ON ELECTRO-OSMOTIC MOBILITY AND ANION MIGRATION IN CAPILLARY ELECTROPHORESIS

The analysis of anions by capillary electrophoresis (CE) with bare silica capillary often uses cationic surfactant to modify the electro-osmotic mobility (EOM) to ensure anions migrating to anode and being detected. The effect of cetyltrimethylammonium bromide (CTAB) concentration in phosphate background electrolyte (BGE) with various ionic strength and pH on the migration of analytes was investigated and reported. A concentration of 0.08 mM CTAB in the BGE starts to reverse cathodic EOM into anodic EOM, and a concentration of 0.30 mM CTAB in the BGE maximizes anodic EOM. Lower EOM is obtained in BGE of higher phosphate concentration while the CTAB concentration and pH are kept constant. Under conditions of constant CTAB and phosphate concentration, higher cathodic EOM was obtained in the BGE of higher pH and lower anodic EOM was obtained in the BGE of higher pH. Although the effect of CTAB concentration, pH, and phosphate concentration on the migration of aromatic anions is complex, the result indicates that the most rapid and effective separation for the anions can be achieved by using a BGE with 0.20 mM CTAB. Furthermore, the relationship between the electrophoretic mobility of anions and the CTAB concentration can be used to determine the critical micelle concentration of cationic surfactant.

Influence of cetyltrimethylammonium bromide on physicochemical properties and microstructures of chitosan–TPP nanoparticles in aqueous solutions

The nanoparticles of chitosan (CS) were prepared using pentasodium triphosphate (TPP) as a crosslinking agent and the influences of cetyltrimethylammonium bromide (CTAB) on the physicochemical properties of the CS–TPP nanoparticles were first studied by laser light scattering, zeta potential, and transmission electron microscopy (TEM). The concentration played a significant role in controlling the particle size of CS and the overlap concentration c ∗ was testified to be about 1.0 mg/mL. The combination of static light scattering (SLS) and dynamic light scattering (DLS) allowed us to obtain more information about the CS–TPP nanoparticles in the presence of surfactant molecules. The addition of CTAB could reduce the hydrodynamic diameter of nanoparticles effectively in the salt solutions and simultaneously increase the zeta potential of the nanoparticles. The effect of CTAB concentration on the size of CS–TPP nanoparticle was also examined. The critical micelle concentration (CMC) of CTAB was used to interpret the complicated complex formed by the polyelectrolyte and the surfactant. Finally, TEM was used to observe the CS–TPP nanoparticles, which were affected by CTAB, to verify the results obtained by light scattering.

Electrochemical characterization of cationic surfactants? adsorption on a disturbed n-alkanethiolate self-assembled monolayer-modified polycrystalline gold electrode

The adsorption of cetyltrimethylammonium bromide (CTAB) on disturbed n-alkanethiolate self-assembled monolayers (SAMs) was investigated by electrochemical methods with potassium ferricyanide [K3Fe(CN)6] as a probe. Compared with the completely restrained signal at ordinary compact n-alkanethiolate SAMs, the electrochemical response of K3Fe(CN)6 at the disturbed n-alkanethiolate SAMs was partly restored and became progressively reversible in the presence of increasing concentrations of CTAB, which was employed to characterize the adsorption of cationic surfactants on hydrophobic SAMs. The effect of CTAB concentration on electrochemical impedance spectroscopy (EIS) plots indicated that CTAB experienced two different types of adsorptive behavior at the disturbed n-alkanethiolate SAMs: monomer adsorption at low concentrations below 1×10−6 M and monolayer adsorption at CTAB concentrations above 1×10−5 M. The adsorption of a series of cationic surfactants with similar structures to CTAB on disturbed n-alkanethiolate SAMs was also explored. These surfactants had similar adsorptive behavior and showed nearly linear adsorption characteristics with the length of their hydrophobic tails.

Effect of Surfactant on the Drainage of an Aqueous Film between an Oil Droplet Approaching a Hydrophobic Solid Surface

The effect of cetyltrimethylammonium bromide concentration above the critical micelle concentration on the profile of aqueous films between an approaching squalene droplet and a hydrophobic silica surface is investigated using the technique of imaging reflectometry. Drainage through the film periphery was observed to display viscous fingering effects and occurred via dendritic channels. This is explained to result from a combination of viscosity and interfacial tension effects. To our knowledge, this is the first time behavior such as this has been observed in a system involving the approach of a droplet to a solid surface.

EFFECT OF SURFACTANT CONCENTRATION ON THE DETERMINATION OF TRANS,TRANS-MUCONIC ACID IN URINE BY CATIONIC MICELLAR ELECTROKINETIC CHROMATOGRAPHY WITH THERMO-OPTICAL ABSORBANCE DETECTION

A rapid method is described for the determination of trans,trans-muconic acid (2,4–hexadienedioic acid), a biomarker of benzene exposure in urine, by micellar electrokinetic chromatography (MEKC) with thermo-optical absorbance (TOA) detection. Addition of the cationic surfactant cetyltri–methylammonium bromide (CTAB) to a pH 7.0 background electrolyte induces a reversal in the direction of electroosmotic flow (EOF), from cathode to anode. The negatively charged trans,trans-muconic acid ion migrates rapidly (< 3 min) toward the anode owing to its electrophoretic mobility supplemented by the surfactant–induced anodic EOF. A rigorous investigation into the effect of CTAB concentration on EOF showed that 0.05 to 5 mM surfactant permits trans,trans-muconic acid to elute before most endogenous urine components. For a urine sample doped with 0.8 mg/L trans,trans-muconic acid, the relative standard deviations of the analyte migration time and peak height were 1.5 % and 5.7 % respectively (n=6), for this home–built analysis system. The detection limit (3 SD) was 0.1 mg/L (7×10−7 M) trans,trans-muconic acid based on calibration standards and the linear dynamic range extended to 50 mg/L.

Surfactant Adsorption on a Clay Mineral: Application of Radiation Scattering

Aqueous mixtures of the synthetic clay mineral Laponite and cetyltrimethylammonium bromide (CTAB) in dilute suspension have been investigated by small-angle neutron scattering (SANS) and dynamic light scattering (DLS). The SANS intensity pattern from the suspension of the pure clay is consistent with that from disks or platelets with diameters of about 30 nm. After addition of CTAB to the clay suspensions, CTAB adsorbs on the face of the clay platelets by cationic exchange and the resulting complex contains excess CTAB in an amount corresponding to about four multiples of the clay's cation exchange capacity (CEC). Contrast matching by isotopic substitution in the solvent indicates that the CTAB/clay complex retains a disk morphology, even if the CTAB in the aqueous medium is in considerable excess. Analyses of the DLS data are interpreted to indicate two possible stable clay platelet configurations in the suspensionsfree clay platelets or clay platelets with CTAB adsorbed in an amount above the CEC and presumably enough to form a stable surfactant bilayer. The effect of CTAB concentration in solution on the aggregation of the clay and its subsequent redispersion is reported, and the influence of clay on CTAB micelle formation is also discussed briefly.