Adsorption Of Cetyltrimethylammonium Bromide Research Articles

Mutual influence of cetyltrimethylammonium bromide and Triton X-100 on their adsorption at the water–air interface

On the basis of surface tension values of the aqueous solution of cetyltrimethylammonium bromide (CTAB) and Triton X-100 (TX-100) mixtures measured at 293K as a function of CTAB or TX-100 concentration at constant TX-100 or CTAB concentration, respectively, the real surface area occupied by these surfactants at the water–air interface was established which is inaccessible in the literature. It appeared that at the concentration of the CTAB and TX-100 mixture in the bulk phase corresponding to the unsaturated monolayer at the water air-interface this area is the same as in the monolayer formed by the single surfactant at the same concentration as in the mixture. In the saturated mixed monolayer at this interface the area occupied by both surfactants is lower than that in the single surfactant monolayer corresponding to the same concentration in the aqueous solution. However, the decrease of the CTAB adsorption is lower than that of TX-100 and the total area occupied by the mixture of surfactants is also lower than that of the single one. The area of particular surfactants in the mixed saturated monolayer changes as a function of TX-100 and CTAB mixture concentration and at the concentrations close to CMC or higher the area occupied by both surfactants is the same. The changes of the composition of the mixed surface monolayer are connected with the synergetic effect in the reduction of the water surface tension by the adsorption of CTAB and TX-100 at the water–air interface. This effect was confirmed by the values of the standard Gibbs free energy of adsorption of both individual surfactants and their mixtures with different compositions in the bulk phase determined by using the Langmuir equation if RT instead of nRT was applied in this equation.

Anion-specificity at water–air interface probed by total reflection X-ray fluorescence (TRXF)

Accumulation of bromide ions in the Stern part of the electrical double layer (EDL) near a Gibbs monolayer of cationic surfactant, cetyltrimethylammonium bromide (CTABr), at the water–air interface was probed by the total reflection X-ray fluorescence (TRXF). A combination of TRXF with surface tension data allowed for the first time to determine the adsorbed amounts of bromide ions in the Stern and diffuse parts of EDL. TRXF and X-ray reflectivity (XR) were employed to probe the competitive adsorption of other anions present in the aqueous solution. The Gibbs monolayers of CTABr were studied in the absence and presence of different anions from the Hofmeister series (Br−, NO3−, F−, Cl−, H2PO4−, ClO4−, and I−) with the aim to compare their affinity to the interface positively charged by adsorption of surface-active CTA+ cation. For studying the effect of anions on adsorption of CTABr, the concentration of the latter was kept constant (10−4M), and that of NaX (X−=Br−, NO3−, F−, Cl−, H2PO4−, ClO4−, and I−) was varied between 10−2M and 10−5M. The results clearly show the competition between anions for the positively charged aqueous–air interface, with F− being the least “surface active” and ClO4− and I− – the most “surface active” anions, in full agreement with the Hofmeister series.

Catalytic carbonization of an uncarbonizable precursor by transition metals in olivine cathode materials of lithium ion batteries

Herein, we report on catalytic effects of transition metals (Me) in phospho-olivines (LiMePO4) on carbonization of cetyltrimethylammonium bromide (CTAB). Carbon coating is the required process to enhance electronic conductivity of phospho-olivines that are used as cathode materials for lithium ion batteries. Primary particles of phospho-olivines were in situ coated with CTAB and the adsorbed carbon precursor was carbonized to provide an electrically conductive pathway. CTAB was successfully carbonized in a significant amount with Fe in phospho-olivines (LiFexMn1−xPO4 with x = 1 and 0.5) even if CTAB is thermally decomposed around 300 °C without any residual mass in the absence of the phospho-olivines. LiMnPO4 was the most inferior in terms of CTAB adsorption and thermal carbonization. LiNiPO4 and LiCoPO4 showed inefficient conversion of adsorbed CTAB to carbon even if their adsorption ability for CTAB is quite large. Also, the effect of the amount of carbon coating on LiFePO4 was investigated, leading to a conclusion that the carbon thickness balanced between electronic and ionic conductances results in the best electrochemical performances of lithium ion batteries specifically at high discharge rates.

Adsorption of cetyltrimethylammonium bromide and/or cetyldimethylbenzylammonium chloride on partly covered hanging mercury drop electrode

Adsorbed cetyldimethylbenzylammonium chloride (CDBACl) or cetyltrimethylammonium bromide (CTAB) on mercury is used as template for the adsorption of CTAB, CDBACl, or their equimolar mixture at 20°C. Adsorptive stripping voltammetry with the two step procedure is used. The results are compared with previously published results on the adsorption of CTAB and CDBACl on mercury and then transferred in base electrolyte. A surfactant is preadsorbed. The adsorption of the second does not remove away from the mercury the first one, as evidenced by the capacitance measurements and the repeated scans. The surfactants were maintained close to each other and in the vicinity of the electrode by the applied electric field. In all cases studied, there was a decrease in the capacitance in the potential range −0.8 to −1V to very low capacitance values forming condensed film. Mixed films and synergy effects were observed. The already adsorbed CTAB on mercury did not permit the desorption–reorientation peaks of CDBACl. Shifts of the capacitance peaks were observed to more positive potentials and were attributed to the occurrence of a slow change in the organization of the monolayer. The electrical state of the preadsorbed surfactant would be of critical importance in the formation of the various structures. The results suggested that the ordering and arrangement of molecules could be controlled by appropriate selection of templates.

Influence of Surface Roughness on Cetyltrimethylammonium Bromide Adsorption from Aqueous Solution

The influence of surface roughness on surfactant adsorption was studied using a quartz crystal microbalance with dissipation (QCM-D). The sensors employed had root-mean-square (R) roughness values of 2.3, 3.1, and 5.8 nm, corresponding to fractal-calculated surface area ratios (actual/nominal) of 1.13, 1.73, and 2.53, respectively. Adsorption isotherms measured at 25 °C showed that adsorbed mass of cetyltrimethylammonium bromide per unit of actual surface area below 0.8 cmc, or above 1.2 cmc, decreases as the surface roughness increases. At the cmc, both the measured adsorbed amount and the measured dissipation increased dramatically on the rougher surfaces. These results are consistent with the presence of impurities, suggesting that roughness exacerbates well-known phenomena reported in the literature of peak impurity-related adsorption at the cmc. The magnitude of the increase, especially in dissipation, suggests that changes in adsorbed amount may not be the only reason for the observed results, as aggregates at the cmc on rougher surfaces are more flexible and likely contain larger amounts of solvent. Differences in adsorption kinetics were also found as a function of surface roughness, with data showing a second, slower adsorption rate after rapid initial adsorption. A two-rate Langmuir model was used to further examine this effect. Although adsorption completes faster on the smoother surfaces, initial adsorption at zero surface coverage is faster on the rougher surfaces, suggesting the presence of more high-energy sites on the rougher surfaces.

Adsorption of cetyltrimethylammonium bromide and cetyldimethylbenzylammonium chloride on a hanging mercury electrode studied by adsorptive transfer stripping voltammetry

The adsorption of cetyltrimethylammonium bromide (CTAB) and cetyldimethylbenzylammonium chloride (CDBACl) on a hanging mercury electrode is studied using adsorptive transfer stripping voltammetry. The surfactants are adsorbed on mercury and are then transferred in KBr or KCl under various conditions, including temperatures from 1 to 40°C, open or closed circuits with different initial potentials, and repeated scans, etc. The results are compared with previously published results on the adsorption of CTAB or CDBACl on mercury, where condensed films were formed and are quite different than those obtained by adsorptive stripping voltammetry. In this case, an absence of condensed film is observed for CTAB. A condensed film with low capacitance value is formed in the case of CDBACl after transfer at low temperatures, or after repeated scans, resulting in reorientation of the molecules to more compact states. Capacity time curves at the potentials where the film is formed show in a few cases a nucleation and growth mechanism, with induction time and studied by the Avrami formulation, while an observed increase of the capacitance with time is attributed to the formation of hemimicelles. The results also indicate the importance of interactions between the hydrophobic chains.

Comparative study of CTAB adsorption on bituminous coal and clay mineral

AbstractAdsorption of cetyltrimethylammonium bromide (CTAB) onto bituminous coal (BC) and a clay mineral, montmorillonite (MMT), was studied. Simultaneous measurements of the CTAB adsorption and zeta potential determination of the adsorption suspensions were carried out. The adsorption isotherms were found to be of the typical Langmuir type; values of the CTAB adsorption capacities were calculated (a m = 0.65 mmol g−1 for coal and a m = 3.24 mmol g−1 for MMT). The shape of the adsorption isotherms was correlated with zeta potential values at the adsorption equilibrium. The adsorption properties of both sorbents were studied by voltammetry on carbon paste electrodes (CPE) modified with coal-CTAB and MMT-CTAB system, respectively. Open circuit sorption with differential pulse voltammetry was performed in order to compare the sorption properties of the systems with the unmodified sorbents. The Cu2+ adsorption on BC and MMT decreased to approximately 50 % and 40 %, respectively. The surface adsorption mechanism of CTAB on coal based on hydrophilic interactions was proposed. In the case of montmorillonite, the CTAB intercalation is expected via ion exchange into the inter-layer space forming a double- or triple-layer arrangement.

Cationic surfactant adsorption on silica gel and its application for wastewater treatment

The adsorption of cetyltrimethylammonium bromide (CTAB), a well known cationic surfactant on silica gel and its application for organic bearing wastewater treatment was studied in detail. The study was conducted for both CTAB-spiked distilled water and real wastewater. The studies on adsorbent dose variation and removal kinetics were conducted to find the optimum dose and equilibrium contact time for CTAB removal. Interestingly, the adsorption capacity was found to be very high for real wastewater and the reaction occurred very rapidly compared to that of CTAB-spiked distilled water samples. The kinetic study revealed that the reaction followed the pseudo-second order reaction kinetics model. The isotherm followed four region isotherm models. The effects of various parameters such as pH, presence of electrolytes and operating conditions on the adsorption process were studied. High adsorption capacity was observed in presence of electrolytes and in alkaline condition. Kinetic study determined the rate limi...

Synthesis of rectangular plate like gold nanoparticles by in situ generation of seeds by combining both radiation and chemical methods

Synthesis of gold nanoparticles of morphology other than spheres or rods in a single step by combining the radiolytic and chemical methods has been investigated. The seeds of gold nanoparticle are generated in situ by irradiating aqueous solution containing 4×10 −4 mol dm −3 gold precursor ion (Au III), 0.1 mol dm −3 cetyltrimethyl ammonium bromide (CTAB), 0.2 mol dm −3 isopropanol, 6×10 −5 mol dm −3 Ag + and 7.2×10 −4 mol dm −3 ascorbic acid (AA) at a dose rate 3.4 kGy hr −1. After a short irradiation time sufficient number of seeds were formed in the solution. Au I present in the system get adsorbed upon these seeds and then subsequently reduction of Au I to Au 0 by ascorbic acid and growth of the seeds results in formation of gold nanoparticles. TEM image confirmed that plate like gold nanoparticles have been formed. The anisotropic growth of nanoparticles was found to be controlled by bilayer structure of CTAB and selective adsorption of silver ion present in the system.

Monomer and micellar adsorptions of CTAB onto the clay/water interface

In this study, the monomeric and micellar adsorption properties of clay samples in aqueous cetyltrimethylammonium bromide (CTAB) solutions were investigated as a function of ionic strength, CTAB equilibrium concentration, and temperature. It was found that the efficiency and effectiveness of CTAB adsorption decrease with increasing temperature, which is the exothermic nature of the adsorption. The sorption of CTAB onto clay increased at the pH range of 3–9 then the adsorbed amount did not change significantly in the range of pH 9–11. The isosteric adsorption enthalpy was found to be − 69.05 kJ/mol. Another observation was that the isotherm shape shifted from an L-shape to an S-shape with increasing temperature. The calculated entropy value (227.46 Jmol − 1 K − 1 ) was quite high and positive. The adsorption capacity increased with increasing ionic strength, as expected. The isotherm shapes for all electrolytes exhibited the change in the case of non-electrolyte and both the efficiency and effectiveness of adsorption decreased with increasing electrolyte concentration. The experimental data concerning adsorption of CTAB at 293 K were applied to the Langmuir model and a high fit was obtained, particularly for monomeric adsorption.

Electrodeposition of nickel/SiC composites in the presence of cetyltrimethylammonium bromide

Electrodeposition of SiC particles with nickel matrix in the presence of cetyltrimethylammonium bromide (CTAB) at two current densities was carried out. Surface chemistry (amount of acidic and basic superficial groups, surface charge, Ni 2+ and Br − adsorption) of the SiC powder in the presence of various CTAB amounts (0–1.1 mM) was studied. Cationic surfactant inhibited adsorption of cations and enhanced adsorption of anions on the positive charged carbide surface, but Br −/Ni 2+ molar ratios for adsorbed ions were higher than in the bath. It was attributed to the CTAB adsorption realized predominantly by hydrophobic interactions between aliphatic chain of the molecule and SiC surface with the positive head group of CTA + pointed toward the bulk solution. Increased SiC incorporation to the composite coating with CTAB addition was observed. Correlation between current efficiency and Br −/Ni 2+ molar ratios for ions adsorbed on SiC was found. The influence of CTAB concentration on the cathodic polarization curves was also determined. Structure of the composite coatings was studied by microscopic observations. Microhardness of the fine-grained metal matrix composites was also determined.

Mechanistic study of adsorption of cetyltrimethyl ammonium bromide on high purity iron using contact angle, polarization resistance and XPS

The mechanism of inhibition of carbon dioxide (CO 2) corrosion of high purity iron by cetyl trimethyl ammonium bromide (CTAB) was investigated by contact angle, polarization resistance and X-ray photoelectron spectroscopy (XPS). The wetting properties, corrosion inhibitor performance and the adsorption of the inhibitor on a high purity iron surface were investigated. Test conditions during corrosion testing were 25 °C, 3 wt% NaCl brine, initial pH 3.9 and 1 bar CO 2 partial pressure. The samples were precorroded for 5 h before inhibitor was added. The inhibitor performance data showed that addition of CTAB significantly reduced the corrosion rate of high purity iron. The decreased corrosion rate seems to be caused by a blocking effect, where the CTAB forms a surface structure on the iron surface. Chemisorption of the CTAB molecules, which could lead to gradually increasing inhibitor efficiency, might be the reason for the slowly decreasing corrosion rate. The XPS data confirmed a gradual accumulation of inhibitor on the surface but did not show any distinct change between different mechanisms at different exposure times. The contact angle measurements showed that the iron was water wet, with a contact angle higher than 160°, at all CTAB concentrations.

Static Threshold Pressure Gradient Characteristics of Liquid Influenced by Boundary Wettability

We propose an experimental setup to measure the threshold pressure gradient (TPG) of microchannels with different wettability surfaces by the static method in microchannels with diameters from 20 μm to 320 μm, and compare the TPG of microchannels with adsorption of cetyl trimethyl ammonium bromide (CTAB) with that without CTAB adsorption. The results show the existence of TPG in microchannels. The TPG of microchannels increases with decreasing hydrodynamic diameter, and the relation between TPG and diameter is in agreement with the single-log normalization. The TPG of a microchannel with CTAB adsorption decreases obviously as compared with the microchannel without CTAB adsorption. The TPG of microchannels with different wettabilities of boundary surface are different, and the resistance of liquid flow can be reduced by changing the wettability of boundary surfaces.

Adsorption of the Cationic Surfactant Cetyltrimethylammonium Bromide to Silica in the Presence of Sodium Salicylate: Surface Excess and Kinetics

The adsorption of cetyltrimethylammonium bromide (CTAB) to silica in the presence of sodium salicylate has been investigated using atomic force microscopy, optical reflectometry, and a quartz crystal microbalance. Salicylate is found to have a dramatic influence on surface adsorption in terms of the kinetics, surface excess, structure of adsorbed aggregates and the mechanical rigidity of the adsorbed film. This is consistent with the bulk solution behavior of more concentrated CTAB-salicylate solutions and reflects the higher local concentration induced by adsorption to the silica surface. Slow adsorption kinetics are found over a wide range of concentrations below the critical micelle concentration.

Adsorption of CTAB on Zeolite A Detected by Surfactant Ion-selective Electrode

Abstract Adsorption of cationic surfactant, cetyltrimethylammonium bromide (CTAB) on zeolite A has been investigated using surfactant-selective electrode technique. The electrode consisted of a polyvinyl chloride (PVC) membrane based on neutral ion-pair carrier complex of cetyltrimethylammonium tetraphenylborate (CTA+TPB−). Adsorbance of CTAB on zeolite A was calculated from the potential and concentration response characteristics of the surfactant-selective electrode to get the surfactant adsorption isotherms. Adsorption isotherm of CTAB was S-shaped. The adsorbance was related to pH and electrolyte in the surfactant solutions.

Adsorption of a jet fuel on a model organic–clay soil: Application of small angle neutron scatteringA paper submitted to the Journal of Environmental Engineering and Science.

Small angle neutron scattering (SANS) data are reported from a system that models the contamination of a clay – organic matter soil from a fuel spillage. The soil was represented as an aqueous dispersion of the synthetic clay mineral Laponite coated with lysine, and the contaminant was a representative jet fuel, quadricyclane, mixed with the detergent cetyltrimethylammonium bromide (CTAB). The adsorbed surface coverage on the clay was estimated. It is shown that the presence of adsorbed lysine considerably enhances the subsequent adsorption of both CTAB and quadricyclane. It is demonstrated that the SANS technique can contribute to the general problem of environmental remediation and retention by probing the interactions of pollutants and clay surfaces.

Estudo da adsorção de surfactante catiônico na matriz inorgânica fosfato de nióbio hidratado

This work describes the study the adsorption of a cationic surfactant, cetyl trimethyl ammonium bromide (CTAB) in the hydrous niobium phosphate matrix. The matrix was characterized by powder X-ray diffraction (DRX), thermal analysis (TG), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and surface area measurements (BET). The Langmuir and Freundlich isothermal models were used in the CTAB adsorption study. The adsorption process wasn`t favorable for the NbOPO4.nH2O in both studied models.

Effects of binding of counterions on adsorption and coalescence

In many industrial applications, ionic surfactants are used in aqueous media in the presence of a mixture of salts. The surface activity of a surfactant in such solutions depends strongly on the ions of different valence. In the present study, surface tensions of aqueous solutions of cetyltrimethylammonium bromide (CTAB) were measured in the presence of sodium bromide and potassium sulfate. The interfacial tension between water and toluene was also measured in the presence of CTAB and these salts. The effects of monovalent (bromide) and divalent (sulfate) counterions on the adsorption of CTAB at air–water and water–toluene interfaces were studied. Coalescence of air bubbles and toluene drops at flat interfaces was studied in these surfactant–salt systems. A stochastic model was used to fit the coalescence time distributions. The significance of the model parameters was discussed. The difference between air–water and water–hydrocarbon interfaces was analyzed in terms of the effects of counterion-binding on adsorption and coalescence. The mean values of the coalescence time distributions were compared with the predictions from seven film-drainage models.

Characterization of well faceted palladium nanoparticles supported on alumina by transmission electron microscopy and FT-IR spectroscopy of CO adsorption

Well faceted palladium nanoparticles supported on alumina were synthesized by a seed-mediated growth technique. The quantification of the different exposed crystallographic planes of these supported palladium nanoparticles was done by TEM analysis. Infrared spectroscopy measurements of an adsorbed probe molecule (CO) allowed to evidence and to quantify the presence of crystallographic planes and defects not seen by TEM. Well faceted palladium nanoparticles (rods, cubes, tetrahedrons, polyhedrons) supported on alumina were synthesized by a seed-mediated growth technique. The quantification of the different exposed crystallographic planes of these supported palladium nanoparticles was firstly done by TEM analysis. To get more information about the exposed crystallographic planes, the amount of defects and the accessibility of palladium sites, infrared spectroscopy measurements of an adsorbed probe molecule (CO) were also performed and enabled to improve and complete the first TEM analysis. In fact, infrared measurements allowed to evidence, and likely to quantify, the presence of crystallographic planes and defects not seen by TEM. Finally, the preferential adsorption of CTAB (cetyltrimethylammonium bromide) on low coordinative crystallographic planes was also experimentally demonstrated.

Dispersion of Carbon Nanotubes in Aqueous Solution with Cationic Surfactant CTAB

Stable homogeneous dispersions of carbon nanotubes were prepared by using cetyl trimethyl ammonium bromide(CTAB)as dispersant.Surface chemistry of the carbon nanotube was investigated by measuring isotherm adsorption and Zeta potential.The stabilization mechanism of the carbon nanotubes in aqueous solution of surfactant CTAB was discussed.In the CTAB solutions,the Zeta- potential of carbon nanotube surface progressively increases with increasing the CTAB concentration, in which the Zeta potential of carbon nanotube changes from-29mV to 65mV.The isotherms of CTAB adsorption on carbon nanotubes indicate a two-step mechanism of adsorption,and the isotherms reach the saturation plateau at CTAB concentration of about 9×10~(-4)mol·L~(-1).The optimum concentration of CTAB to obtain a stable homogeneous dispersions of carbon nanotubes is about 9×10~(-4)mol·L~(-1).