Containing Cetyltrimethylammonium Bromide Research Articles

Label-free immunosensor based on a one-step CTAB intercalated graphene nanocomposite for hepatitis C virus detection

A new label-free immunosensor containing cetyltrimethylammonium bromide (CTAB) intercalated-graphene oxide (GO) on a polythiophene (PTh) film one-step electrosynthetized is described for detection of hepatitis C antibodies (Anti-HCV). This electroactive film also acted as a substrate for immobilizing the biorecognition element. The ability of the biosensor to bind Anti-HCV was monitored by the square wave voltammetry (SWV) technique through the decrease in anodic peaks. The intercalation of GO nanosheets between CTAB and PTh was very stable, achieving a variation coefficient of approximately 0.65% for redox peaks after 30 cycles, and was also demonstrated as a diffusion-controlled process with excellent electrochemical reversibility. The immunosensor exhibited a linear response range from 0.2 to 8 ng∙mL−1, good reproducibility (square R equal to 0.993, low relative error < 1%), and a limit of detection at 0.07 ng∙mL−1 of Anti-HCV, achieving the clinical range for HCV diagnostic. Furthermore, this approach shows promise for constructing a practical and accurate immunosensor for HCV diagnostic and screening in chronic phases and monitoring other HCV biomarkers utilizing this technology.

Urea-Assisted Synthesis of Mesoporous TiO2 Photocatalysts for the Efficient Removal of Clofibric Acid from Water.

Mesoporous TiO2 photocatalysts intended for the advanced removal of clofibric acid (CA) from water were synthesized by the sol-gel method in a medium containing cetyl-trimethyl-ammonium bromide (CTAB) and urea, using either ethanol or isopropanol to dilute the TiO2 precursor. The activation of the samples was undertaken at 550, 650 and 750 °C. The XRD revealed that the nature of the solvent resulted in significant differences in the anatase-to-rutile ratios obtained at different temperatures. The specific surface area values were situated between 9 and 43 m2·g−1 and the band gap values were similar for all the samples. The photocatalytic activity of the prepared samples was examined for the degradation of CA, an emergent water contaminant. The photocatalytic tests performed under UV-A irradiation revealed that the photo-reactivity of these materials depends on the calcination temperature. The best results were obtained for the samples calcined at 750 °C, which showed high yields of CA elimination, as well as almost complete mineralization (over 95%) after 180 min of reaction. Good results in terms of catalyst reusability in the reaction were found for the catalyst showing the highest photo-reactivity. Therefore, the samples can be considered good candidates for future water remediation applications.

A comparative study of electrodeposition routes for obtaining silver coatings from a novel and environment-friendly thiosulphate-based cyanide-free electroplating bath

In the present study, silver coatings are deposited from a novel cyanide-free thiosulphate-based electroplating bath containing cetyltrimethylammonium bromide (CTAB), 1,4-diazabicyclo[2.2.2]octane (DABCO), and pyridine-3-carboxylic acid (Niacin). LSV and EIS are carried out to demonstrate the metal-complex interactions and the reduction mechanism during electroplating. Depositions are carried out by both DC and pulse galvanostatic methods for comparison. XRD and EDS analysis confirmed the presence of elemental silver in the coatings. The SEM analysis and surface profilometry show the morphological variations and changes in surface roughness as a function of the electrodeposition route. Nano-indentation measurements reveal that the samples deposited under pulse conditions have a hardness of 196 ± 6.5 and 227 ± 15.6 VHN at current densities of 0.1 and 0.01 mA/cm2, respectively. By comparing the results obtained via both the deposition routes, it can be concluded that the pulse galvanostatic route can obtain a highly compact and adherent silver coating having a mirror-finish appearance that lasts for a long time under ambient indoor environment. Therefore, the developed bath can be used for producing mirror-bright silver coatings for aesthetic usage via pulse galvanostatic route.

Interactions of Cetyltrimethylammonium Bromide with 1,3-Dioxolane in Water: A Study of Viscosity and Volumetric Properties

Densities and viscosities of ternary mixtures containing cetyltrimethyl ammonium bromide (CTAB) in aqueous solution of 1,3-dioxolane have been measured at 5 K intervals from 298.15 to 313.15 K and at atmospheric pressure. The experimental results of viscosity and density have been analyzed by using Jones-Dole equation and Masson equation. The values of constants A and B of Jones-Dole equation have been interpreted in terms of solute-solute and solute-solvent interactions. The standard partial molar volume,Vφ 0 at infinite dilution were determined from Masson equations. The structure making/breaking capacity of solute is interpreted with the help of Helper equation. The positive value of Helper′s constant (∂2Vφ 0/∂T2)p and the negative value of dB/dT shows that CTAB in studied organic solvent predominantly acts as a structure-maker.

Application of solid waste of ductile cast iron industry for treatment of wastewater contaminated by reactive blue dye via appropriate nano-porous magnesium oxide

The solid waste of ductile iron industry, which contains at least 88.0% magnesium oxide, is one of the toxic materials, leading to land contamination. On the other hand, the removal of reactive dyes from wastewaters is difficult required effective adsorbent like nano-porous MgO. The novelty of present investigation is based on nano-porous magnesium oxide production by precipitation from the solid waste to treat the wastewaters contaminated by reactive dye which is abundantly used in the textile industry. In order to improve the adsorptive properties of extracted MgO powder, the combinations of surfactants, containing cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS) and polyoxyethylene octyl phenyl ether (TX100) were applied based on the mixture design algorithm in the precipitation. The effects of processing factors such as surfactant composition, powder calcination temperature, surfactant dose and pH were evaluated on the removal efficiency. The results revolved that the combination of SDS and TX100, 1:1, plays an effective role in the production of particles with the appropriate average pore size, 16 nm. The adsorbent prepared in the optimum condition indicated a significant affinity for the removal of reactive dye which shows relatively pH-independent efficiency in the range of 3–9. The applied producer for fabrication of adsorbent eventually overcomes the pH-dependent problem for the toxic dye uptake, leading to produce the adsorbent with maximal adsorption capacity of 1000 mg g−1.

Spectrophotometrical analysis for fabrication of pH-independent nano-sized γ-alumina by dealumination of kaolin and precipitation in the presence of surfactant composites.

The challenge with γ-Al2O3 is its pH-dependent removal efficiency and relatively low adsorption capacity in recovery of wastewaters contaminated by cationic dyes. Therefore; the objective of present investigation was to fabricate a pH-independent nano-sized alumina powder by dealumination of kaolin for uptake of dye. The dealumination of meta-kaolin was carried out by nitric acid solution and the amorphous aluminum hydroxide was precipitated with ammonia in the presence of combined surfactants containing cetyltrimethylammonium bromide (CTAB), polyethylene glycol (PEG) and polyoxyethylene octyl phenyl ether (TX100). The nano-sized gamma alumina particles were fabricated after calcination at 800 °C and then were analyzed based on spectrophotometrical method. The rod-like nano-particles with average width of 5 nm and length of 20 nm were synthesized by precipitation in the presence of admixed surfactant, CTAB-TX100, which improves the removal efficiency due to efficient modification in the interaction of particles. TX100 also showed a significant affinity for increasing the specific surface area because of ability to prevent the particle aggregation which provides a potential for synthesis of alumina adsorbent without foaming, normally observed in the presence of CTAB. Both of mentioned powders indicated relatively pH-independent removal efficiency with higher adsorption capacity. Moreover, adsorption isotherm parameters were determined to verify the improvement of removal efficiency. The presented fabrication technique eventually overcame the pH-dependent recovery problem which is feasible for the development of adsorbents because the starting material is abundant, very low energy is needed, no hazardous waste is generated and applicable in the acidic environments.

Microfluidic continuous flow synthesis of functional hollow spherical silica with hierarchical sponge-like large porous shell

Microfluidics brings unique opportunities for engineering micro-/nanomaterials with well-controlled physicochemical properties. Herein, using a miniaturized multi-run spiral-shaped microreactor, we develop a flow synthesis strategy to continuously produce hollow spherical silica (HSS) with hierarchical sponge-like pore sizes ranging from several nanometers to over one hundred nanometers. The formation of HSS is realized by mixing two reactant flows, one containing cetyltrimethylammonium bromide (CTAB) and diluted ammonia and the other 1,3,5-trimethylbenzene (TMB) and diluted tetraethyl orthosilicate (TEOS), at a flow rate as high as 5 mL/min. The effect of the reactant concentration and the flow rate on the structural change of the resultant materials is examined. Functional small-sized nanoparticles (magnetic nanoparticle, quantum dot, and silver nanoparticle) can be separately assembled into HSS and high molecular weight protein (bovine serum albumin) can be successfully loaded into HSS and delivered into cancer cells afterward, making them promising in the fields of separation and purification, bioimaging, catalysis, and theranostics.

The Growth of FeCoNi nanoparticles Electrodeposited from CTAB-assisted Sulfate Electrolyte

This paper presents our preliminary investigation on the deposit growth characteristic of FeCoNi nanoparticles prepared using potentiostatic electrodeposition. The FeCoNi electrodeposition was conducted in sulfate electrolyte containing cetyl trimethylammonium bromide (CTAB). Prior to the deposit preparation, cyclic voltammetry analysis was carried out to determine co-deposition potential of iron, cobalt and nickel ions. Mechanism of the deposit growth was studied based on the recorded potentiostatic current transient. The (i/im) versus (t/tm) plot indicated that nucleation and particles growth of FeCoNi was found to follow the instantaneous type closely, but with a very fast particle growth phase before entering diffusion stage. This growth characteristic produced fine nanoparticles of FeCoNi with homogeneous size distribution.

Distance readout of Al content with naked eyes on a cotton thread

We described a facile method for distance-based detection of aluminum on a thread based on the adsorption of formed complex onto thread. Chrome azurol S (CAS) containing Cetyltrimethylammonium Bromide (CTMAB) were used as chromogenic reagent, which reacts with aluminum to form AL-CAS-CTMAB complex on a thread. The complex was adsorbed onto thread to generate a colored band. Aluminum contents could be quantified by measuring the length of colored band on the thread using a ruler, thereby eliminating the need for electronic readout devices and trained personnel. This instrument-free method has features of low cost, easy to operation, fast analysis speed, disposability and low reagents/sample consumption. Moreover, considering that the thread fiber has adsorption capability to various molecules such as metal-ligand complexes and biomolecules, we believe that this technique holds the potentials to be widely adaptable to distance-based chemical and biochemical analysis.

Application of nano particle for enhancement of foam stability in the presence of crude oil: Experimental investigation

The use of gas is one of the most common methods in the oil industry for enhancing oil recovery. However, problems such as gas uptake due to the low density of the gas reduce the efficiency of this method. The formation of foam reduces the relative permeability of the gas and improves this technique. The foam generated by the combination of water and gas does not show enough stability, and thus surfactant injection method has been used for many years. However, foam stabilized by the surfactant is problematic in the presence of oil. The advent of nano technology has shown that the foam stabilized by nanoparticles can tolerate the presence of oil.In this project, the foam generated by nanoparticle and the surfactant is studied. Then, the effect of different kinds of crude oils, with different viscosities on foam structure, has been investigated. For studying the foamability and foam stability, the static method of “mixing” is used with the experimental setup designed for this job. Then, by measuring the interfacial tension (IFT) and surface tension (ST) between solutions, oil and the air, the entering coefficient (E), spreading coefficient (S), lamella number (L) and bridging coefficient (B) are calculated, and the relations between obtained values and the observed behaviors has been investigated.The results show that the solution containing Cetyltrimethyl ammonium bromide (CTAB) and nano silica is undispersed, so the foam studies are not carried out for this system. But the solution containing Sodium dodecyl sulfate (SDS) and nano silica is completely dispersed and generates a desirable foam. In addition, nano silica increases the foamability and foam stability of the SDS solution. Regarding the effects of crude oil, the presence of crude oil reduces foam stability and by increasing oil saturation, the stability reduction is observed to be greater. It is also observed that by increasing oil viscosity, foam stability and foam properties improve.

Study on the preparation of ordered mesoporous carbon-based catalyst from waste microalgal biomass for the synthesis of biokerosene

Investigation on preparation of novel ordered mesoporous carbon-based catalyst (MCC catalyst) containing super-acid sites from waste microalgal biomass was established. The waste microalgal biomass was partially carbonized at 400 °C for 2 h obtaining biochar; then the obtained biochar was introduced to a sulfonation process using concentrated sulfuric acid. The sulfonation was established at 150 °C for 15 h producing sulfonated biochar. The MCC catalyst was prepared through condensation–evaporation method in an alkaline media containing cetyltrimethylammonium bromide (CTAB) as structure directing agent. The parameters of the condensation including time of evaporating and CTAB content were investigated while fixing temperature at 90 °C during the process. A special hydrothermal treatment was also applied to the preparation of the MCC catalyst in order to expand its mesopores for more convenient with large molecule diffusion. The catalyst activity was well demonstrated by converting linseed oil to biokerosene which could be used as biokerosene—component for blending with aviation fuels. The MCC catalysts were characterized by X-ray diffraction, infrared spectroscopy, energy dispersive X-ray, scanning electron microscopy, transmission electron microscopy, nitrogen adsorption–desorption method and ammonia-temperature programmed desorption techniques. The biokerosene composition was determined by gas chromatography–mass spectroscopy method.

Synthesis and Electrochemical Characterization of Palladium Crystals Enclosed by (100) Facets by Seed-Mediated Fabrication

Pd crystals enclosed by (100) facets were prepared in an aqueous solution containing cetyltrimethylammonium bromide (CTAB) as the capping agent and ascorbic acid as the reducing agent at 30, 40, and 50°C by a modified seed-mediated fabrication technique. Regardless of the reaction temperature, the absorption peak between 300 and 400 nm assigned to PdCl42- decreased with an increase in the reaction time after the addition of ascorbic acid in the PdCl42- aqueous solution containing CTAB because of Pd deposition. The field emission-scanning electron microscopy images showed that the Pd crystals were enclosed by only (100) facets, and their fractions depended on the reaction temperature. The ratios of the peak current at 0.54 and 0.48 V were 0.60, 0.54, and 0.47 for the samples prepared at 30, 40, and 50°C, respectively, suggesting that the proportion of the (100) facet on the Pd surface was higher at lower temperatures.

Generation of parallelepiped-shaped mesopores and structure transformation in highly stable ferrierite zeolite crystals by framework desilication in NaOH solution

Desilication and recrystallization of a low-silica NaK-form ferrierite (NaKFER) were conducted by one-step hydrothermal method in sodium hydroxide solution containing cetyltrimethylammonium bromide (CTAB). The attack by NaOH induced unprecedented mesopore formation in highly stable ferrierite crystals through framework desilication. Interestingly, the generated mesopores are parallelepiped-shaped and oriented along the [001] directions (10 MR) of the FER structure. The CTAB surfactant could be inserted between the layers of ferrierite crystals under the assistance of NaOH. This process was associated with the formation of occluded mesopores and led to partial delamination of layered crystals. Under severe treatment conditions, NaKFER transformed to GIS and SOD phases, successively. The samples were characterized by XRD, N2 sorption, SEM, TEM, EDS, TG, etc. The influence of NaOH concentration, temperature, reaction time, CTAB and cation form of the parent zeolite was investigated in order to study the mechanism of mesopores formation, delamination process and phase transformation of ferrierite. Phase diagrams were established to show the transformation process of NaKFER as a function of NaOH concentration, reaction time and temperature.

Leuco-crystal-violet micelle gel dosimeters: Component effects on dose-rate dependence

Designed experiments were performed to produce empirical models for the dose sensitivity, initial absorbance, and dose-rate dependence respectively for leucocrystal violet (LCV) micelle gel dosimeters containing cetyltrimethylammonium bromide (CTAB) and 2,2,2-trichloroethanol (TCE). Previous gels of this type showed dose-rate dependent behaviour, producing an ∼18% increase in dose sensitivity between dose rates of 100 and 600 cGy min-1. Our models predict that the dose rate dependence can be reduced by increasing the concentration of TCE, CTAB and LCV. Increasing concentrations of LCV and CTAB produces a significant increase in dose sensitivity with a corresponding increase in initial absorbance. An optimization procedure was used to determine a nearly dose-rate independent gel which maintained high sensitivity and low initial absorbance. This gel which contains 33 mM CTAB, 1.25 mM LCV, and 96 mM TCE in 25 mM trichloroacetic acid and 4 wt% gelatin showed an increase in dose sensitivity of only 4% between dose rates of 100 and 600 cGy min-1, and provides an 80% greater dose sensitivity compared to Jordan’s standard gels with similar initial absorbance.

The phase behaviors of cationic and anionic aqueous mixtures and the usage as templates for synthesis of mesoporous materials

Liquid crystals formed in aqueous mixtures of cationic and anionic surfactants were used as structure- directing templates for preparation of mesoporous silicas. For this purpose, micellar particle sizes and liquid crystal regions in the mixed system containing cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS) were investigated by Melvin laser particle size analyzer and polarizers, respectively. The formation of large organized assemblies was closely related to both the total surfactant concentrations and mixing ratios. Micelles formed at low total concentration while liquid crystals formed at high total concentration. The mixtures of CTAB and SDS favored the formations of large organized assemblies when the molar fraction of CTAB was 0.30 or 0.70. Using tetraethoxysilane as precursor and liquid crystals as templates, mesoporous silicas were prepared at different total concentrations of surfactants when molar fraction of CTAB was fixed at 0.70. Transmission electron microscopy results revealed that ordered mesoporous silicas with lamellar pore channels were prepared. Nitrogen adsorption-desorption determinations showed that these materials exhibited a pore size about 4.5 nm. In addition, the surface areas increased significantly with the increase of total surfactant concentrations. This work provided a simple and effective approach to synthesize lamellar mesoporous silicas.

Ionic Liquid-Assisted Electron Transfer in Micelles for Simultaneous Deposition of Uniform Ag Nanoparticles at Electrode Surface and in Bulk Microemulsions

The synthesis of metal nanoparticles (NPs) with controllable size from aqueous or organic solutions has long been a scientific and technological challenge. Here we show a unique electrodeposition approach from ionic liquid microemulsions (ILM) which enables simultaneous fabrication of uniform controllable Ag NPs at both electrode substrate and in bulk solution. In the ILM system containing cetyltrimethylammonium bromide (CTAB), butanol, 1-butyl-3-methyl-imidazolium chloride ([BMIM][Cl]), and an aqueous solution of silver nitrate, uniform Ag NPs with a narrow size distribution of 20 ~ 50 nm could be electrodeposited on the cathode surface at low deposition current (0.2~1.5 mA·cm-2). The size and size distribution of Ag NPs can be adjusted by tuning the deposition current, time, temperature and IL concentrations. Remarkably, at high deposition current (>1.50 mA·cm-2) the electrochemical reduction of Ag NPs takes place not only on the electrode surface but also beyond into the bulk microemulsion phase. Uniform Ag NPs of diameters 2 ~ 13 nm thus can be obtained from the bulk ILMs. It is found that the ionic liquid plays a quaternary role as a soft template and co-surfactant for the formation of micro-reactors, an electrolyte for enhancing conductivity, and an electron carrier facilitating electron transport between nanodropletsfor Ag reduction. The electrocatalytic activity of the electrodeposited Ag NPs has been investigated for oxidation of glycerol for potential applications in direct alcohol fuel cells.

Bromide (Br−) ion-mediated synthesis of anisotropic palladium nanocrystals by laser ablation

Anisotropic growth of Pd nanoparticles in bromine (Br) containing solution has been studied by pulsed laser ablation. For size and shape control different solutions like water, sodium dodecyl sulphate (SDS) (anionic surfactant), and (Br−) ion containing cetyltrimethylammonium bromide (CTAB) (cationic surfactant) and electrolyte (KBr) were used. In laser ablation surrounding liquid plays a dominant role in controlling size and directional growth. Absorption spectra of as-generated Pd nanoparticles undergo modification with time in different solutions due to Br− ion-mediated directional growth. In water and SDS quasi-spherical and spherical Pd nanoparticles with mean size of 14 and 8nm, respectively, and in CTAB decahedron and icosahedron shape Pd nanocrystals with mean size 65nm were observed. When strong Br− ion source KBr was used sharp edged cuboid shaped large Pd nanoparticles were observed. Surface energy modification due to preferential chemisorption of Br− ions onto {100} planes of Pd resulted in formation anisotropic Pd nanostructures enclosed with {100} planes. The nanocubes exhibit broad plasmon resonance around 250–280nm. Further, size of nanocuboids were controlled by using mixed solutions of KBr with SDS and CTAB for tunable plasmon resonance wavelength from 230 to 550nm.

Oil swollen surfactant gel based synthesis of metal oxides nanoparticles: An attractive alternative for the conventional sol gel synthesis

Metals (Zr, Zn and Cu) containing oil swollen surfactant gels have been utilized as precursors for the preparation of metal oxides (ZrO2, ZnO and CuO) nanoparticles. No metal alkoxide, external gelating agent or any other intricate molecule have been utilized to reinforce gelation; gel stage has been achieved simply through judicial adjustment of water to surfactant ratio and salinity of the reaction mixture. Unlike, several previously published reports, in this approach surfactant has been added not to just increase the viscosity of solution but it has also formed rod shaped gelatinous micelles in response to the variation in water to surfactant ratio, which endowed mechanical strength to the gel. The effect of nature of metal salt on mechanical properties of gel has also been investigated. Zn and Cu containing cetyltrimethylammonium bromide (CTAB) gels have been found to be strongest and weakest, respectively. Metal containing CTAB gels were heat treated at various temperatures (600, 700 and 800°C) in order to obtain metal oxides nanoparticles. The effect of calcination temperature on crystallinity, particle size and morphology of the metal oxides nanoparticles has also been investigated. A comparison between ZrO2 nanoparticles prepared using conventional sol gel and oil swollen surfactant gel method has also been carried out in terms of crystallinity, particle size and optical property.

Chemically Modified Electrodes for Recessed Microelectrode Array

Chemical modifications on recessed microelectrode array, achieved via electrodeposition techniques are reported here. Silicon-based gold microelectrode arrays of 10μm microband and microdisc array were selected and functionalised using sol-gel and nanoporous gold (NPG) respectively. For electrochemically assisted self-assembly (EASA) formati6154on of sol-gel, electrode surface was first pre-treated with a self-assembled partial monolayer of mercaptopropyltrimethoxysilane (MPTMS) before transferring it into the sol containing cetyltrimethyl ammonium bromide (CTAB)/tetraethoxysilane (TEOS):MPTMS (90:10) precursors. A cathodic potential is then applied. It was found that larger current densities were required in ensuring successful film deposition when moving from macro- to micro- dimensions. For NPG modification, a chemical etching process called dealloying was employed. NPG of three different thicknesses have been successfully deposited. All the modified and functionalized microelectrode arrays were characterized by both optical (SEM) and electrochemical analysis (cyclic voltammetry and impedance spectroscopy). An increase in surface area and roughness has been observed and such will benefit for future sensing application.

Electrochemical Synthesis of Continuous Controllable Ag Nanoparticles from Quaternary Ionic Liquid Microemulsions and Electrocatalytic Activity

The synthesis of metal nanoparticles (NPs) with controllable size from aqueous or organic solutions has long been a scientific and technological challenge. Here we show a unique electrodeposition approach from ionic liquid microemulsions (ILM) which enables simultaneous fabrication of uniform controllable Ag NPs at both electrode substrate and in bulk solution. In the ILM system containing cetyltrimethylammonium bromide (CTAB), butanol, 1-butyl-3-methyl-imidazolium chloride ([BMIM][Cl]), and an aqueous solution of silver nitrate, uniform Ag NPs with a narrow size distribution of 20∼50 nm could be electrodeposited on the cathode surface at low deposition current (0.2∼1.5 mA·cm−2). The size and size distribution of Ag NPs can be adjusted by tuning the deposition current, time, temperature and IL concentrations. Remarkably, at high deposition current (>1.50 mA·cm−2), the electrochemical reduction of Ag NPs takes place not only on the electrode surface, but also beyond into the bulk microemulsion phase. Uniform Ag NPs of diameters 2∼13 nm thus can be obtained from the bulk ILMs. It is found that the ionic liquid plays a quaternary role as a soft template and co-surfactant for the formation of micro-reactors, an electrolyte for enhancing conductivity, and an electron carrier facilitating electron transport between nanodroplets for Ag reduction. The electrocatalytic activity of the electrodeposited Ag NPs has been investigated for oxidation of glycerol for potential applications in direct alcohol fuel cells.