Solutions Of Cetyltrimethylammonium Bromide Research Articles

Co-Solubilization of the Binary Mixture of 1-Naphthol and 2-Naphthol in the Water Micellar Solution of Sodium Cholate and Cetyltrimethylammonium Bromide

The micellar co-solubilization of α- and β-naphthol and their binary mixture with surfactants sodium cholate (SC) and cetyltrimethylammonium bromide (CTAB) is examined. The micellar solubilization of 2-naphthol (2-NpOH) in SC is entropic, and it is an energetically more favored process than the micellar solubilization of 1-naphthol (1-NpOH). The capacity of the solubilization by CTAB for solubilizing 1- and 2-naphthol is about eight-times higher at 4CMC than at 2CMC (four- and two-times the critical micelle concentration, respectively), which can be explained by the change in the micelle structure with an increase in the total concentration of the CTAB surfactant. For the same CMC values of the examined surfactants, SC has a higher solubilization capacity for naphthols in comparison to the solubilization capacity of CTAB, which is explained by the existence of hydrogen bonds between the building units and solubilizates that are formed in the SC micelles. For each molar ratio of the micellar binary mixture...

Research on catalytic pyrolysis of algae based on Py-GC/MS.

In order to improve the quality of catalysis products of algae, composite molecular sieve catalyst was prepared by digestion and crystallization of HZSM-5 to reduce the oxygen content of the catalytic products. According to the analysis of the pyrolysis products, the best preparation conditions were chosen of tetra propylammonium hydroxide (TPAOH) solution 2.0 mol l−1, cetyltrimethylammonium bromide (CTAB) solution 10 wt%, crystallization temperature 110°C, digestion–crystallization time: 24–24 h. The results indicate that the main function of catalysts is to promote the conversion of alcohols into hydrocarbons by reducing energy barriers. Catalysed by the composite molecular sieve, the content of alcohols in the pyrolysis products decreased from more than 30% to less than 10%, the content of hydrocarbons increased from 20% to nearly 60%, while all the adverse components remained at a low level, which indicates that the catalytic pyrolysis products are of high quality. The great deoxidation effect of composite molecular sieves is not only due to the expansion of the range of organic matter during re-pyrolysis, but also the increasing of the residence time of pyrolysis products inside the structure for the external mesoporous structure.

Features of Field Electron Emission when Changing the Positional Order in Colloidal Solutions and Cetyltrimethylammonium Bromide

The features of the field electron emission through a drop of a colloidal solution of a surfactant (structured colloidal solution of cetyltrimethylammonium bromide) are studied. The results indicate the possibility of using data on the angular distribution of the electron emission intensity stimulated by a pulsed electric field from structured liquid media to study the positional order and geometry of molecular associates in solutions.

Surfactant Micelles Enable Metal‐Free Spirocyclization of Keto‐Ynamides and Access to Aza‐Spiro Scaffolds in Aqueous Media

Micellar solutions of cetyltrimethylammonium bromide (CTAB) surfactant allow the spirocyclization of keto‐ynamides in an aqueous medium without recourse to transition‐metal catalysis, enabling access in water to naturally occurring aza‐spiro compounds with potential in drug discovery. The reaction was monitored by dynamic light scattering (DLS) and cryogenic transmission electron microscopy (cryo‐TEM), which determined the morphology and change in size of the micelles before and after incorporation of the substrate and achievement of 5‐endo‐dig cyclization inside the micelles.

Dynamic Equilibrium in the Cetyltrimethylammonium Bromide-Au Nanoparticle Bilayer, and the Consequent Impact on the Formation of the Nanoparticle Protein Corona.

Nanoparticles in ionic solutions are usually surrounded by stabilizing molecules that avoid aggregation and determine their surface properties, which strongly influence their behavior. The present work aims to shed light on the static vs dynamic nature of the cetyltrimethylammonium bromide (CTAB) bilayer on gold nanoparticles and to understand its effects on nanoparticle evolution in biological systems. A systematic study of the CTAB bilayer of Au nanorods and nanospheres was carried out, exploring the role of excess free surfactant in solution on the surface properties of nanoparticles and their colloidal stability. The results indicated the presence of a CTAB bilayer in which the external layer was in rapid dynamic equilibrium with the free surfactant in solution. The internal surfactant layer of the gold nanospheres was also found to be in dynamic equilibrium. Conversely, the gold nanorods had a permanent internal layer. Consequently, the CTAB-nanoparticle dispersions always contained free CTAB in excess to maintain the colloidal stability of the NPs. In contrast, decreasing the free CTAB concentration resulted in nanoparticle aggregation. The impact of the dynamic equilibrium on the exposure of particles to biological fluids and on the formation of the nanoparticle protein corona was studied, revealing the different fates of the nanoparticles, which depended on the amount of free CTAB in solution.

Fluorescence resonance energy transfer between cerium ion(III) and levofloxacin in micellar solution and its analytical application to the determination of levofloxacin

Fluorescence resonance energy transfer between cerium ion(III) and levofloxacin is studied in a micellar solution of cetyltrimethyl ammonium bromide. A non-fluorescent 1:2 complex was formed between excited cerium ion(III) and ground state levofloxacin. The fluorescence of cerium ion(III) is quenched by levofloxacin with the quenching in accordance with the Stern–Volmer relation. The analytical relationship was established between the ratio of the fluorescence of levofloxacin present and absent cerium ion (III) and the concentration of levofloxacin, which helped to estimate the content of levofloxacin directly.

Fabrication and Performance Evaluation of Pd‐Cu Nanoparticles for Hydrogen Evolution Reaction

AbstractHerein, the effects of different types of surfactants including sodium dodecyl sulfate (SDS), cetyltrimethyl ammonium bromide (CTAB), and t‐octyl phenoxy polyethoxy ethanol (Triton X‐100, TX‐100) were presented on the hydrogen evolution reaction (HER) at the surface of carbon paste electrode (CPE) modified with Pd−Cu nanoparticles. Firstly, Cu nanoparticles with average diameters at about 80 nm were electro‐deposited at the CPE surface in H2SO4 solution containing CTAB and CuSO4 by potentiostatic method. Then, Pd−Cu bimetallic nanoparticles with diameters at about 75 nm were prepared through galvanic replacement reaction between PdII ions and Cu particles. The synthesized Cu nanoparticles were covered by CTAB in solution and surface tension of the nanoparticles were decreased, and consequently stabilized. Also, the surfactants play different roles on the HER depending on the electrode polarity and surface charges. The electro‐catalytic activity of the Pd−Cu/CPE and nano‐Cu/CPE towards HER was found to be highest in the presence of SDS. The effects of galvanic replacement reaction and type of surfactants on kinetic parameters of the HER such as cathodic electron transfer coefficient and exchange current density were comparatively investigated.

Polyurethane/Bentonite/Chitosan Blend for Improved Thermal and Protection Microorganisms for Paint Application

In this study polyurethane synthesis was carried out using the pre-polymer method using the reaction of Toulena Diisocyanate (TDI) with oleic acid-based palm oil polyols. To provide heat resistance properties for coating paint material, add bentonite (B) and chitosan (K) to polyurethane samples. The concentrations of bentonite and chitosan used were 1% b / b, 2% b / b and 3% b / b, respectively. Palm oil-based oleic acid polyol samples were analyzed for chemical compound structure using Fourier Transform Infrared (FTIR) obtained by O-H group at a wavelength of 3437.15 cm-1. Preparation of bentonite and chitosan purification was done by adding cetyltrimethyl ammonium bromide solution to bentonite solution and CH3 3 COOH 2% solution and NaOH into chitosan solution, successfully increasing the d-spacing layer with the acquisition of 1.144 nm to 1.513 nm in bentonite and 1.117 nm to 1.475 nm in chitosan and an increase in the value of heat resistance is evidenced by the results of observations using XRD and Thermogravimetric Analysis (TGA).

Vortex ring processes allowing shape control and entrapment of antibacterial agents in GO-based particles

Vortex ring (VR) processes have proved highly effective in tailoring the morphology/shape of particles prepared from nanoclays, silica nanocolloids, magnetic nanoparticles and different polysaccharides. Herein, we have prepared toroidal-, teardrop-, jellyfish-, and cap-shaped vortex ring particles by dripping an aqueous suspension of graphene oxide (GO) into a cetyl trimethylammonium bromide (CTAB) aqueous solution that played the role of coagulating agent. Interestingly, the GO suspension exhibited liquid crystalline features. We demonstrated how controlling the drop impact force against the liquid surface was critical to produce VR particles with such intriguing shapes. With the purpose of controlling the drop impact force, we studied the drop density/viscosity, the speed at which the drop impacts the surface of the liquid pool and the surface tension of the CTAB solution. Finally, we also demonstrated the antibacterial activity of the resulting GO-based VR particles against Escherichia coli and Bacillus subtilis, and discussed about the origin of such a behaviour. In particular, we investigated the occurrence of (1) membrane damage by physical contact between GO and bacteria, (2) GO-induced oxidative stress, or (3) CTAB released into the bacteria culture, the antiseptic and disinfectant action of which may ultimately kill bacteria.

Enhancement of flotation response of fine low-rank coal using positively charged microbubbles

This study investigates the possibility of using positively charged (PC) microbubbles in pulp conditioning to improve the flotation response of fine low-rank coal. The surface properties of the coal are characterized by means of a zeta potential analyzer, scanning electron microscopy, and X-ray photoelectron spectroscopy. Batch flotation tests are conducted with the use of PC microbubbles, cetyltrimethylammonium bromide (CTAB) solution, and tap water in pulp conditioning. The roles of PC microbubbles in the coal flotation are illustrated by combining observations of particle–particle and particle–bubble interactions and extended Derjaguin–Landau–Verwey–Overbeek (DLVO) theory calculations. The results indicate that fine low-rank coal is negatively charged and contains a large amount of oxygen. In addition, the rough structure and the presence of numerous impurity mineral particles on the surface of low-rank coal afford adsorption sites for water molecules. These features of the coal render traditional collectors ineffective, whereas the presence of PC microbubbles significantly enhances flotation recovery. However, increasing CTAB concentration cannot continuously improve flotation performance with the use of PC microbubbles, possibly because the excess CTAB molecules can form bilayer or micelle adsorption structures on the coal surface, particularly on the mineral surface. The presence of PC microbubbles promotes particle–particle agglomeration and particle–bubble attachment by providing an additional attractive electrical double-layer force and enhancing hydrophobic interactions. The extended DLVO theory calculations agree well with the experimental results.

Facile in situ Encapsulation of Highly Dispersed Ni@MCM‐41 for the Trans‐Decalin Production from Hydrogenation of Naphthalene at Low Temperature

AbstractNi@MCM‐41 catalyst that has uniformly distributed, highly dispersed Ni nanoparticles (about 2.3 nm) was designed and successfully synthesized by in situ encapsulation of Ni in the channels of MCM‐41. This catalyst exhibits excellent thermal stability and hydrogenation activity. Water insoluble nickel acetylacetonate (Ni(acac)2) was first dissolved aqueous solution of cetyltrimethyl ammonium bromide (CTAB) and encapsulated in micelles of CTAB. Sodium silicate was used as a silicon source to rapidly hydrolyze and then wrap on the micelle surface to synthesize the MCM‐41 zeolite. The MCM‐41 zeolite encapsulating Ni(acac)2 was synthesized within a short time (4 h) at 120 °C. Compared with conventional supported catalysts, thus 3 wt.% Ni@MCM‐41 has ultra‐small uniformly distributed Ni nanoparticles and exhibits improved activity for the hydrogenation of naphthalene to decalin at very low reaction temperatures. The TOF and the apparent activation energy of Ni@MCM‐41 and the conventional catalysts (Ni/MCM‐41 and Pt/MCM‐41) were evaluated and compared. And the catalysis mechanism was analyzed. Furthermore, this Ni@MCM‐41 catalyst offers an additional advantage of selectivity in decalin isomerization; 92 % trans‐decalin selectivity was achieved at a wide temperature range.

Gram-Scale Synthesis of Isolated Monodisperse Gold Nanorods.

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

Catalytic fast pyrolysis of rice husk over hierarchical micro-mesoporous composite molecular sieve: Analytical Py-GC/MS study

In order to promote efficient production of hydrocarbons, catalytic fast pyrolysis (CFP) of rice husk (RH) over catalysts is performed using Py-GC/MS. The catalyst is hierarchical micro-mesoporous composite molecular sieve prepared under different conditions including different concentrations (1.5 mol/L, 2.0 mol/L, 2.5 mol/L, 3.0 mol/L) of NaOH solution, different mass fraction of cetyltrimethylammonium bromide (CTAB) solution, different temperatures (90℃, 100℃, 110℃, 120℃) and durations (12 h, 24 h, 36 h). The fabricated hierarchical catalyst with HZSM-5 structure as the core and MCM-41 structure as the shell is characterized using N2 adsorption-desorption measurement and transmission electron microscopy. As the experimental results suggest, the highest value of total peak area of all the chemical compounds is obtained at 600℃. The fabricated hierarchical catalyst exhibit pronounced deoxygenation and excellent selectivity of aromatics. The maximum relative abundance of hydrocarbons (54%), maximum relative abundance of aromatics (39%) and value of selectivity of monocyclic aromatics (65%) are obtained by comparison with different hierarchical catalysts. Besides, the catalyzed transformation of large oxygenated compounds into hydrocarbons can be improved as a function of significant activation of hydrocarbon pool.

Temperature dependent solution properties of amino acids in colloidal solutions

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

Hyaluronan-assisted synthesis of silver nanoparticles and nanowires

Silver nanowires (NWs) were successfully synthesized in high yield in cationic surfactant solutions of cetyltrimethylammonium bromide (CTAB) with hyaluronan (HA) additive. Most of the NWs had diameter of 10–30 nm and length of more than tens of microns. The carboxylate group of HA provides a stronger electrostatic interaction with the cationic heads of CTAB and promotes formation of lengthened cylindrical micelles. Silver ions were reduced by addition of ascorbic acid and heating, and the embryonic silver seeds promoted growth of silver NWs along the one-dimensional direction of the cylindrical micelles. Presence of any gold nanoparticles or nanorods in the solution can prominently inhibit the formation of silver seeds and decrease the yield of silver NWs.

Co-solubilisation of a binary mixture of isoflavones in a water micellar solution of sodium cholate or cetyltrimethylammonium bromide: Influence of micelle structure

During co-solubilisation of a binary mixture of daizdein (D) and genistein (G) in a micelle water solution of sodium cholate (SC), G synergistically affects the solubilisation of D, while D antagonistically affects the solubilisation of G. In SC micellar binary mixtures of isoflavones, the interaction parameter (coefficient of activity) of molecule D is <1, while for G it is >1, i.e. D molecules are thermodynamically more stable than in the micellar pseudophase without G. It is assumed that formation of SC secondary micelles have a role in the thermodynamic stabilisation of D, especially when the content of the micellar binary mixture of isoflavones leads to a molar fraction of 1. In micellar co-solubilisation of the same binary mixtures with cetyltrimethylammonium bromide (CTAB), a mutual antagonistic effect occurs between components of the mixture related to their solubilisation. This is probably the result of competition between D and G for micelle binding sites.

Removal Properties of Anionic Dye Eosin by Cetyltrimethylammonium Organo-Clays: The Effect of Counter-Ions and Regeneration Studies.

The organo-clays (OCs) were prepared by a cation exchange reaction between surfactant (cetyltrimethylammonium, C16TMA) from different counterions (Bromide, Chloride, and Hydroxide). The effect of the counterions was investigated on the physico-chemical properties of the prepared organo-clays. The highest uptake of organic cations (1.60 mmol/g) was achieved using cetyl trimethylammonium bromide solution and the lowest value (0.93 mmol/g) was obtained after modification with cetyl trimethylammonium hydroxide solution starting from the same initial ratio of mmol/g of clay greater than 2.40. The arrangement of C16TMA cations within the interlayer space was assumed to be perpendicular with a tilt angle of 32° to the plane of clay sheets instead of being parallel to the clay surface using C16TMAOH solution at the same ratio. Different techniques were used to characterize these materials. The thermal stability of these organ-clays was investigated using an in-situ X-ray diffraction (XRD) technique. The decomposition of the surfactant moiety occurred at temperatures higher than 215 °C and was accompanied with a shrinkage of the basal spacing value to 1.42 nm. These materials were applied in the removal of an acid dye “eosin.” The removed amount of eosin depended on the initial concentrations and the content of surfactants in the organo-clays. The removal of eosin was found to be an endothermic process. The maximum amount of 90 mg/g was achieved. The preheated treatment temperature of two selected OCs did affect the removal properties of eosin. A progressive reduction was observed at temperatures higher than 200 °C. The regeneration of spent OCs was studied and acceptable removal efficiency was maintained after 4 to 6 cycles depending on the used initial concentrations.

The distinct roles of the anaphylatoxin receptors C5aR1, C5aR2 and C3aR during experimental invasive meningococcal disease

In this study, the experimental surface tensions were measured for aqueous solutions of cetyltrimethyl ammonium bromide, 1-propanol, 2-propanol, and 1-butanol with a pendant drop apparatus. The temperature and pressure of all experiments were 298.15 K and 1 bar, respectively. Subsequently, a model based on the equality of the chemical potential of components at the interface and the bulk liquid was used. The results of this part showed that the surface tensions were reproduced well. The average absolute deviation percent of surface tension was 1.11. Then the surface tensions of (cetyltrimethylammonium bromide + alcohols) aqueous mixtures were measured at different concentrations. Moreover, the critical micelle concentrations of the applied systems were determined. The present model was used for aqueous mixtures of (cetyltrimethylammonium bromide + alcohols). The average absolute deviation percent of surface tension was 2.72, so the model successfully predicted the surface tension for aqueous solutions of (cetyltrimethylammonium bromide + alcohols). Furthermore, the results of the model proved that the presence of alcohols decreased the surface coverage of cetyltrimethylammonium bromide and increased the values of the critical micelle concentration.

Experimental study on thermal performance of a pulsating heat pipe with surfactant aqueous solution

In this work, the thermal performance of pulsating heat pipe (PHP) using surfactant aqueous solution as working fluid was experimentally investigated. The cetyl trimethyl ammonium bromide (CTAB) was applied for preparation of surfactant solution in the concentration range of 0.025–0.25 wt%. It is found that the adding of CTAB can significantly reduce the surface tension and improve the wettability, thus enhance heat transfer between the tube wall and working fluid due to the increase in the liquid film area. The thermal performance of CTAB solution PHP depends greatly on the input power, filling ratio and surfactant concentration. Experimental results indicate that the heat transfer enhancement of PHP with CTAB solution is apparent at higher input power when the concentration is very high. Comparing to the water PHP, the thermal resistance of 0.25 wt% CTAB solution is decreased by 48.5% at the input power of 100 W when filling ratio is kept as 50%.

SYNTHESIS OF COPPER NANOPARTICLES USING ASCORBIC ACID AND CETYL TRIMETHYL AMMONIUM BROMIDE

Objective: The present study highlights the development of a method to synthesize copper nanoparticles (CuNPs).Methods: CuNPs were developed using 0.01 M copper penta sulfate and 0.11 M of ascorbic acid (AA) and 0.03 M of cetyl trimethyl ammonium bromide solution. The synthesized CuNPs were differentiated through filtration and washed by water (deionized). CuNPs were kept in dialysis bag 70 KD in a 250 mL glass beaker along with distilled water. The assembly was kept on a magnetic stirrer for 24 h at 500 rpm. Then, the dialysis bag containing CuNPs solution was filtered by a filter assembly with 0.2 μm nylon filter. The filtered CuNPs were spray dried with the help of spray drier.Results: The prepared CuNPs were found to be 440 nm with zeta potential of −10 mV and polydispersity index 0.314.Conclusion: The investigation deciphers the promising and material technique to synthesis of CuNPs by methods for synthetic reduction utilizing strategy using AA (0.2 M) and sodium hydroxide (1 M), and Syloid 244FP.