Surfactant Cetyltrimethylammonium Bromide Research Articles

Surface activity of N-graphene quantum dot in presence of CTAB surfactant

An interface can be subtly engineered utilizing nanoparticle-surfactant interactions by controlling surface activity and surface charge balancing. In this research, the effect of N-doped Graphene Quantum Dot particles (N-GQDs) and Cetyl trimethylammonium bromide surfactant (CTAB) presence in the air/water interface is explored. We found on the study of interplay of N-GQD with CTAB that N-GQDs are surface active particles. Thereafter, the effect of concentration ratio of CTAB to N-GQD on surface tension and elasticity is investigated up to critical micelle concentration (CMC). The results demonstrate the surface activity of N-GQDs when there is no surfactant molecules (1 wt% N-GQD, surface tension (ST) ∼53). In addition, the results manifest that due to CTAB molecules' attachment to the N-GQD particles, more efficient surface-active mixtures are created. At higher surfactant loadings, the excess CTAB monomers compete with CTAB/ N-GQDs mixtures to reach the interfaces, causing mixture to come back into the bulk of liquid verified by elasticity evaluations. The preparation of N-GQDs and as a result its mixture includes economical and easy experimental protocols, and according to the synergistic effects defeat the individual components constraints i.e. –at 1% N-GQD+0.25 CMC CTAB the dynamic surface tension lies below pure CTAB CMC line.

Influence of surfactant concentration on structural properties and corrosion behaviour of electrodeposited Ni–SiO2 nanocomposite coatings

Abstract In this study, Ni–SiO2 nanocomposite coatings were deposited on the surface of X70 steel by performing direct current electrodeposition. The effect of different concentrations of cetyltrimethylammonium bromide surfactant (0.3, 0.5, 1, and 2 g L−1) on particle distribution and corrosion behaviour of the coatings was analysed. The structural properties of the obtained coatings were evaluated by scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy analysis, X-ray diffraction, and atomic force microscopy. The corrosion behaviour of the coatings was tested by potentiodynamic polarisation and electrochemical impedance spectroscopy. The results showed that the electrodeposited coatings obtained from the electroplating bath with 1 g L−1 of surfactant modified the surface morphology of the Ni–SiO2 nanocomposite coating and presented a finer and more uniform microstructure. The results of the phase structure analysis showed that the addition of the surfactant in the electrodeposition process changed the preferred orientations for the coatings from (111) to (220) and (200) planes. The anti-corrosion performance of the resulting coating produced in the presence of 1 g L−1 of surfactant was significantly higher than the anti-corrosion performance of the other coatings and showed a lower corrosion rate.

In-situ design of hierarchical durable silica-based coatings on polypropylene films with superhydrophilic, superhydrophobic and self-cleaning properties

Superhydrophobic surfaces are receiving increasing attention due to their real-world applications. However, these surfaces suffer from a lack of durability and complicated synthetic processes. This research uses a combination of a simple in-situ coating process between oxygen-activated polypropylene films and unreacted silane monomers. The in-situ process uses a modified Stöber method with the addition of the surfactant cetyltrimethylammonium bromide (CTAB) which aggregates silica (SiO 2) particles in a basic aqueous solution. This resulted in a layer of covalently bonded hierarchical coating of individual and aggregated SiO 2 “flakes” and particles. These coatings were found to have at least double the surface roughness than samples prepared without CTAB with superhydrophilic properties due to their high surface roughness and hydrophilic surface chemical groups. A second layer of fluorocarbon silane monomers was reacted with the hydroxyl groups on the hierarchical SiO 2 coating resulting in films with excellent superhydrophobic and self-cleaning properties. The sample containing aggregated SiO 2 particle structures exhibited higher chemical and physical durability against external irritations including adhesion, different pH levels, detergent, abrasion and UV radiation by retaining high contact angles and low rolling angles. Samples coated with flake structures were negatively affected by mechanical irritations. This simple in-situ SiO 2 coating process in combination with different concentrations of CTAB has not been investigated and has promising potential for many practical applications such as superhydrophilic, superhydrophobic and self-cleaning surfaces.

Modified magnetite nanoparticles synthesized using cetyltrimethylammonium bromide and their application to immobilize trypsin

This paper presents the study of the properties of immobilized trypsin from the bovine pancreas. Fe3O4 nanoparticles as magnetically detachable carriers were synthesized using surfactant cetyltrimethylammonium bromide (CTAB). CTAB allows for obtaining non-agglomerated nanosized particles with superparamagnetic properties. The support surface was functionalized with amino groups using (3–aminopropyl)triethoxysilane and next glutaraldehyde. Immobilization of trypsin was carried out by covalent binding of trypsin with modified magnetite. The activities of native and immobilized trypsin were measured using 1% casein. The effect of reuse at nine cycles on the activity of the immobilized trypsin was tested. The activity of immobilized trypsin on magnetite was studied during storage at 4 °C for 28 days. It was found that in optimal conditions at a temperature of 55 °C and pH 7.6. The Michaelis–Menten constant Km was 5.59 ± 0.37 mM and the maximum reaction rate vmax was 10.74 ± 1.85 mM min−1 for immobilized trypsin, compared to a Km of 4.63 ± 0.34 mM and a vmax of 8.74 ± 0.88 mM min−1 for free trypsin at a temperature of 37 °C. High activity of the immobilized trypsin during reusability, presents that immobilized trypsin might find potential application in practice.

The influence of surfactants of different classes on the toxicity of diesel fuel forSaccharomycetes

The effect on the survival of the yeastS. cerevisiaeof mixtures of diesel fuel (summer variety) with four representatives of different classes of surfactants – cationic (cetyltrimethylammonium bromide), anionic (sodium dodecyl sulfate), nonionic (Tween-80) and polymeric (polyvinyl alcohol) – was studied. It was shown that diesel fuel and two representatives of the classes of anionic and cationic surfactants (sodium dodecyl sulfate and cetyltrimethylammonium bromide) in the mixture exhibited higher toxicity than when exposed individually. At the same time, the toxicity of diesel fuel mixed with a nonionic surfactant (Tween- 80) and a polymer surfactant (polyvinyl alcohol) was comparable to their individual toxicity.

Surfactant-mediated enhanced FRET from a quantum-dot complex for ratiometric sensing of food colorants.

Herein we report that a surfactant modified quantum dot-complex (S-QDC; with λem-515 nm) nanocomposite, as a donor fluorophore, exhibits enhanced Förster resonance energy transfer (FRET) efficiency to an acceptor organic dye (λem-576 nm) in comparison to only the QDC. The proposed S-QDC (consisting of a ZnS quantum dot, zinc quinolate inorganic complex and cetyltrimethylammonium bromide (CTAB) surfactant) provides the unique and selective ratiometric visual detection of organic dyes present as food colorants in commercial chili powder, tomato ketchup and mixed fruit jam. Notably, the S-QDC shows a limit of detection (LOD) as low as 2.2 nM in the linear range of 0.17-4.89 μM for food colorants. Furthermore, the present work will bring new possibilities to unravelling the chemistry among surfactants, inorganic complexes and quantum dots to make newer optical materials with futuristic scope of utilization ranging from optical sensors to light emitting devices.

Synthesis of barium hexaferrite nano-platelets for ethylene glycol ferrofluids

The exchange of cetyltrimethylammonium bromide (CTAB) surfactant with barium hexaferrite magnetic nanoparticles enables the synthesis and dispersion of a new generation of permanent magnetic ferrofluids.

A CTAB-assisted PANI-MoS2 nanosheet flower morphology for the highly sensitive electrochemical detection of hydrazine.

In this work, cetyl trimethylammonium bromide (CTAB)-assisted polyaniline-molybdenum disulfide (CPANI-MoS2) nanosheets with a flower morphology have been synthesized through in situ polymerization and a hydrothermal method. The composite was analyzed for structural modification through X-ray diffraction (XRD) to examine chemical changes and the presence of functional groups via Fourier transform infrared (FTIR) and Raman spectroscopy techniques. The surface morphology was identified by field-emission scanning electron microscopy (FESEM) and high-resolution transmission electron microscopy (HR-TEM) techniques. The CPANI-MoS2 nanosheet glassy carbon electrode (GCE) offers a novel strategy for the electrochemical detection of carcinogenic hydrazine. The cyclic voltammetry (CV) curve demonstrated a quasi-reversible behaviour with a high-surface area. Furthermore, differential pulse voltammetry (DPV) analysis of hydrazine detection showed a wide linear range from 10 μM to 100 μM, a low limit of detection of 0.40 μM, and a high sensitivity of 7.23 μA μM cm-2. The determination of hydrazine in a water sample and the recovery percentage were found to be 100.31% and 103.73%, respectively. The CPANI-MoS2 nanosheet GCE significantly contributed to the high electroanalytical oxidation activity due to the CTAB surfactant modifying the flower-like nanosheet morphology, which enables the easy adsorption of hydrazine analyte species and exhibits a high current rate with a rapid detection response.

Ultrasmall Pt NPs-modified flasklike colloidal motors with high mobility and enhanced ion tolerance.

Chemically powered colloidal motors propelled by the self-phoretic effect have attracted widespread attention. However, the low motion efficiency and ion tolerance hinder their application in complex media. Herein, we report a scalable and simple method to synthesize 2.6 nm Platinum nanoparticles (Pt NPs) in the nanoporous wall of carbonaceous flasklike colloidal motors in a ligand-free manner. The obtained Pt NPs-modified flasklike colloidal motors (Pt-FCMs) are propelled by the catalytic decomposition of H2O2 fuels. They exhibit ultrafast mobility with an instantaneous velocity of 134 μm s-1 at 5% H2O2, which is equivalent to 180 bodylengths per second. Particularly, these Pt-FCMs have an enhanced ion tolerance, due to the higher catalytic activity of small-sized Pt NPs in the carbonaceous wall. Furthermore, the direction of motion could be reversed by adding cationic surfactant cetyltrimethylammonium bromide. Such ultrasmall Pt NPs funtionalized flasklike colloidal motors exhibit a great potential utilization in the field of biomedicines and environmental technology.

Silica-coated gold nanorods biofunctionalization for localized surface plasmon resonance (LSPR) biosensing

We introduce here the engineering of nanobiosensors designed from gold nanorods coated with an ultrathin layer of silica (AuNR@SiO2) and biofunctionalized with antibodies for the Localized Surface Plasmon Resonance (LSPR) biosensing of proteins. Despite the outstanding properties of AuNRs, their use for LSPR biosensing is limited due to the presence of the surfactant cetyltrimethylammonium bromide (CTAB) – mandatory for their synthesis - which forms a strongly-bounded and positively-charged bilayer at their surface and significantly complicates their bio-functionalization. When coated with a thin layer of silica, these nanomaterials exhibit an improved sensitivity to refractive index change which augurs for better analytical performances. Here, we undertook an in-depth investigation of the biofunctionalization of AuNR@SiO2via three different routes to design and test a label-free LSPR biosensor operating in solution. In the first route, we took advantage of the negatively charged external silica shell to immobilize anti-rabbit IgG antibody by electrostatic physisorption. In the second and third routes, the silica surface was reacted with thiol or aldehyde terminated silanes, subsequently utilized to covalently attach anti-rabbit IgG antibody to the surface. The resulting nanoprobes were characterized by a wide range of physical methods (TEM, XPS, DLS, ELS and UV-Visible spectroscopy) then tested for the biosensing of rabbit-IgG. The three nanobiosensors maintain an excellent colloidal stability after analyte recognition and exhibit extremely high analytical performances in terms of specificity and dynamic range, with an LoD down to 12 ng/mL.

A Robust Switchable Oil-In-Water Emulsion Stabilized by Electrostatic Repulsions between Surfactant and Similarly Charged Carbon Dots.

How to control the stability of oil-in-water (O/W) emulsions is one of the main topics for scientists working in colloidal systems. Recently, carbon dots (CDs) have received great interest as smart materials because of their excellent physicochemical properties and versatile applications. Herein, for the first time, advanced and switchable O/W emulsions are presented that are stabilized by the synergistic effect of cationic surfactant cetyltrimethylammonium bromide CTAB (emulsifier) and similarly charged CDs (stabilizer). In the formulated emulsion, the cationic surfactant molecules are adsorbed at the oil and water interface to decrease the interfacial tension and enrich the drops with a positive charge to ensure intensive electrostatic repulsions among them. On the contrary, cationic CDs are distributed in the water phase among the droplets to reduce the water secretion and prevent flocculation and droplet coalescence. The stabilizing effect is found to be universal for emulsions of a range of oil phases. Furthermore, the formulated emulsion is found to be switchable between "stable" and "unstable" modes by adding an equivalent of anionic surfactant sodium dodecyl benzene sulphonate (SDBS). The stabilized and switchable O/W emulsions are believed to have wide practical applications in water purification, pharmaceuticals, protein recognition, as well as catalysis.

Electroosmotic flow in fused deposition modeling (FDM) 3D-printed microchannels.

Electroosmotic flow (EOF) was determined in tridimensional (3D)-printed microchannels with dimensions smaller than 100µm. Fused deposition modeling 3D printing using thermoplastic filaments of PETG (polyethylene terephthalate glycol), PLA (polylactic acid), and ABS (acrylonitrile butadiene styrene) were used to fabricate the microchannels. The current monitoring method and sodium phosphate solutions at different pH values (3-10) were used for the EOF mobility (µEOF ) measurements, which ranged from 2.00×10-4 to 12.52×10-4 cm2 V-1 s-1 . The highest and the smallest µEOF were obtained for the PLA and PETG microchannels, respectively. Adding the cationic surfactant cetyltrimethylammonium bromide to the sodium phosphate solution caused EOF direction reversion in all the studied microchannels. The obtained results can be interesting for developing 3D-printed microfluidic devices, in which EOF is relevant.

Study on Volumetric, Compressibility and Viscometric Behavior of Cationic Surfactants (CTAB and DTAB) in Aqueous Glycyl Dipeptide: A Thermo-Acoustic Approach

This study aims to understand how glycyl dipeptide affected the compressibility, volumetric behavior and viscometric behavior of the cationic surfactants CTAB (Cetyltrimethylammonium bromide) and DTAB (dodecyltrimethylammonium bromide). Information on solute-solute, solute-solvent, and solvent-solvent interactions has been inferred using the quantification of density (ρ), speed of sound (u) and viscosity in aqueous media containing glycyl dipeptide in the temperature range 293.15-313.15 K at an interval of 5 K. The data from the aforementioned research have been used to enumerate numerous volumetric and compressibility metrics that aid in the collection of information about the interactional behavior of the system under consideration. The study suggests that CTAB interacts strongly compared to DTAB with dipeptide, and it also significantly dehydrates glycyl dipeptide. The difference in water-water interactions caused by the loss of hydrophobic hydration of the surfactant molecules upon the addition of cationic surfactants may be the cause of the variation in determined parameters with surfactant concentration. Consideration of the structural rearrangement of molecules that may occur in the system has been used to explain the results of viscosity and computed factors related to viscosity. The patterns of competitive intermolecular interactions in the ternary (dipeptide + water + surfactant) system have been used to analyze the trends of all the parameters. The study may be helpful to understand the stability and structural changes in protein-surfactant systems mediated through various interactions that may be present in the system.

Adsorption of nitrate in water by CTAB-modified MgFe layered double hydroxide composite biochar at low temperature: Adsorption characteristics and mechanisms

In this study, for the purpose of improving the removal effect of biochar on nitrate in wastewater at lower temperature, MgFe layered double hydroxides (MgFe-LDHs) were precipitated on the surface and in the pores of corn stover biochar (BC) in the presence of surfactant cetyltrimethylammonium bromide (CTAB) to prepare a novel adsorbent MgFe-CTAB-LDHs/BC. The result shows that BC has abundant pore structure and MgFe-LDHs has been uniformly loaded on the surface of BC and in the pores, which greatly reduced the agglomeration of LDHs. Part of CTAB was on the surface of BC, making it more positively charged, and the other part entered the interlayer of LDHs, changing the interlayer spacing, which is beneficial to adsorption. Meanwhile, the hydroxyl groups and metal hydroxides in LDHs and numerous active groups of BC enhanced the adsorption capacity through synergistic effect. The successful preparation of MgFe-CTAB-LDHs/BC was proved by various characterization analyses and the adsorption mechanism of nitrate on MgFe-CTAB-LDHs/BC was investigated through experimental demonstration and characterization analysis. The adsorption kinetics and isotherm studies also showed that the adsorption rate of MgFe-CTAB-LDHs/BC for nitrate was improved, and it still had a good adsorption effect at lower temperature. This study aims to provide a novel environmentally friendly adsorbent for nitrate adsorption at lower temperature.

Facet Selectivity of Cetyltrimethyl Ammonium Bromide Surfactants on Gold Nanoparticles Studied Using Molecular Simulations.

We have studied facet selectivity of cetyltrimethyl ammonium bromide (CTAB) surfactants of varying alkyl tail lengths (C17TAB and C10TAB) during their adsorption on a spherical gold metal nanoparticle (MNP) using umbrella sampling and well-tempered metadynamics techniques in molecular simulations. We show that the surfactants strongly adsorb with their alkyl tails wrapped around the MNP. The adsorption morphologies are dictated by the strong preference of the polar head group of the surfactants to adsorb on to the atoms that lie between the facets of the MNP, that is, in the vicinity of low-coordinated gold atoms. The alkyl tails do not display any strong facet preference. Owing to the longer alkyl tails, C17TAB molecules pack together better than the C10TAB molecules in the adsorbed state on the MNP. These findings suggest that the regions near the edges of the facets and low-coordinated atoms are expected to be preferentially covered with the adsorbed surfactants.

Surfactant aided electrocoagulation/flotation using punched electrodes for the remediation of salicylic acid from wastewater

Performance of a batch electrocoagulation/floatation (ECF) setup using punched aluminium electrodes for the remediation of salicylic acid in the presence of cetyl-trimethyl ammonium bromide (CTAB) surfactant is evaluated in this research. The operational parameters of ECF technology were optimized in this research and based on the optimized operating conditions with electrolysis time of 50 min, electrode gap of 2 cm, electrolyte concentration of 0.6 g/L, pH of 7.2, a current density of 2.25 mA/cm2, and 20 mg/L of CTAB dose, about 92.1 ± 2.5% of salicylic acid removal was attained corresponding to an initial salicylic acid concentration of 50 mg/L. The salicylic acid degradation in ECF was observed to follow first−order−rate kinetics. The electrode corrosion and sludge generation were also evaluated. After the ECF-based treatment, a considerable reduction in phytotoxicity was observed, which was suitable for the germination of the Vigna radiata. About 2 mM of green fuel H2 gas was also produced during the treatment. The sludge generated during ECF was reduced nearly by 2−folds when cationic surfactant CTAB was added to the electrolyte. Moreover, the energy consumption of 0.328 kWh and treatment cost of 0.21 US$ (16.72 INR) were observed for the treatment of per m3 of salicylic contaminated wastewater. Treatment efficiency of salicylic acid in a real municipal wastewater matrix was about 65 ± 3.4% at optimum operating conditions, contributing to 47% of total organic carbon removal. Thus, ECF process was found to be effective in removal of salicylic acid from contaminated water.

Ultrafine metallic cobalt nanoparticle encapsulated in N‐doped carbon as high‐efficiency catalysts for reduction of 4‐nitrophenol

Novel and efficient ultrafine metallic cobalt nanoparticles encapsulated in N‐doped carbon catalysts are prepared via a facile method from pyrolysis of ZIF‐67‐x%CTAB, which is modified by CTAB (cetyltrimethyl ammonium bromide). The content of surfactant CTAB can control the crystal size of ZIF‐67, which further determines the Co particle size of Co@CN‐x%CTAB. The as‐prepared ZIF‐67‐x%CTAB and Co@CN‐x%CTAB were characterized by X‐ray powder diffraction (XRD), scanning electron microscopy (SEM), high‐resolution transmission electron microscopy (HRTEM), Brunauer−Emmett−Teller (BET), and X‐ray photoelectron spectroscopy (XPS). Co@CN‐0%CTAB could not maintain the primary morphologies of ZIF‐67‐0%CTAB with the collapse of skeleton. However, the Co@CN‐3%CTAB and Co@CN‐5%CTAB catalysts inherit the original morphologies with skeleton constriction. It indicated that Co@CN catalysts could maintain the skeleton structure of ZIF‐67 by adding CTAB during the preparation process. The particle size of Co@CN decreased with the increasing of CTAB content. Moreover, the addition of CTAB facilitated the formation of Co‐Nx species on catalyst surface. The kinetic rate constant of Co@CN‐5%CTAB catalyst was 0.99 min−1, which is 2.5 times as high as that of Co@CN‐0%CTAB catalyst for 4‐nitrophenol reduction. The excellent catalytic performance of Co@CN‐5%CTAB may be due to the presence of Co (0) species generated in situ during the calcination process, the smaller Co nanoparticles and more Co‐Nx site on the surface of the catalyst.

Tipping Gold Nanobipyramids with Titania for the Use of Plasmonic Hotspots to Drive Amine Coupling.

Designing plasmonic photocatalysts with spatially controlled catalytic sites is an effective strategy to boost the sunlight-driven chemical transformation efficiency through plasmonic enhancement. Herein, we describe a facile method for the synthesis of TiO2-tipped Au nanobipyramids (NBPs) to give (Au NBP)/t-TiO2 nanodumbbells. The surfactant cetyltrimethylammonium bromide concentration is the key factor in the construction of this type of unique nanostructure. The photocatalytic aerobic oxidative coupling of amines using the plasmonic photocatalysts with the dumbbell-like and core@shell structures indicates that the TiO2-tipped ends for the photo-reduction and the exposed adjacent Au surface for the photo-oxidation on (Au NBP)/t-TiO2 can significantly improve the photocatalytic activity. The underlying mechanism of the photocatalytic oxidative coupling of benzylamine over (Au NBP)/t-TiO2 has been thoroughly investigated. Both experimental and simulation results for (Au NBP)/t-TiO2 and (Au nanorod)/t-TiO2 confirm the important effect of the plasmonic hotspots on the enhancement of the photocatalytic activity.

Friction dynamics of human hair treated with water or cationic surfactant aqueous solution

AbstractCationic surfactants are adsorbed on the surface of human hair and exhibit a lubricating effect. Here, we evaluated the friction when the hair treated with water or 1 wt% cationic surfactant (cetyltrimethylammonium bromide) aqueous solution was rubbed by a contact probe equipped in a sinusoidal motion friction evaluation system. Because of the rough structure of the cuticle on the human hair surface, an oscillatory phenomenon with a frequency of 50–70 Hz was observed when untreated hair was rubbed with a contact probe. On the other hand, the oscillatory phenomenon was not observed when the hair contained a large amount of water because stick–slip phenomena were inhibited on the soft, swollen hair surface. Furthermore, the change in kinetic friction coefficient and delay time, which is a normalized value of the time difference between the reaction of the friction force to accelerated motion, from untreated hair, Δμk and Δδ, was almost zero. However, we found a large difference in Δμk and Δδ for the hair treated with cationic surfactant aqueous solution. The treatment with cationic surfactant reduced both friction parameters, Δμk and Δδ, indicating that the treatment induced not only the frictional force but also the profile at the beginning of frictional sliding. The significant lubrication is due to cationic surfactant adsorption on the hair surface. These data imply that the smoothness of hair treated with a cationic surfactant is related to a reduction in friction coefficient and delay time δ.

Interaction of Direct Blue 86 with cationic surfactant micelles: spectroscopic, conductometric and thermodynamic aspects

Abstract Due to the amphiphilic structure of surfactants, aqueous surfactant solutions can behave like very good solvents and dissolve both polar and non-polar solutes. This study reports on the solubilisation of a direct dye (Direct Blue 86) in a micellar medium using the cationic surfactant cetyltrimethylammonium bromide (CTAB). Solubilisation of dyes is important for their subsequent removal from aqueous media. UV spectroscopy and conductometry, among others, were used to quantitatively evaluate this process. The extent of solubilisation, the interaction between the molecules and the stability of the processes were checked using the partition coefficient (K x), the binding constant (K b) and the corresponding thermodynamic parameters. From the results, it could be concluded that the solubilisation of Direct Blue 86 is a spontaneous process supported by an increase in entropy. It was also found that the micellar medium CTAB is efficient for solubilisation and binding of the dye and can be used economically.