Tetrabutylammonium Bromide Concentration Research Articles

Temporal Evolution of Interparticle Potentials of PMMA Colloids in CHB/Decalin.

Colloidal dispersions composed of polymethylmetacrylate particles dispersed in a mixture of cyclohexyl bromide and decalin find widespread use as model systems in optical microscopy experiments. While the system allows simultaneous density and refractive index matching, preparing particles with hard potentials remains challenging, and strong variations in the physical parameters of samples prepared in the same manner are commonly observed. Here, we present data on the measurement of forces between individual pairs of particles in highly diluted dispersions over the course of tens of days using the blinking optical tweezers method. Our results show that the variations in the particle properties are indeed caused by a temporal evolution of the particles' charging. Additional measurements of the influence of the addition of tetrabutylammonium bromide (TBAB) to the dispersions show that already small concentrations of added TBAB salt drastically decrease the electrostatic forces between colloidal particles. However, small, non-negligible contact potentials remain even at the highest TBAB concentrations added.

Yield and Selectivity Improvement in the Synthesis of Carbonated Linseed Oil by Catalytic Conversion of Carbon Dioxide.

Carbonation of epoxidized linseed oil (CELO) containing five-membered cyclic carbonate (CC5) groups has been optimized to 95% by reacting epoxidized linseed oil (ELO) with carbon dioxide (CO2) and tetrabutylammonium bromide (TBAB) as catalysts. The effect of reaction variables (temperature, CO2 pressure, and catalyst concentration) on the reaction parameters (conversion, carbonation and selectivity) in an autoclave system was investigated. The reactions were monitored, and the products were characterized by Fourier Transform Infrared Spectroscopy (FT-IR), carbon-13 nuclear magnetic resonance (13C-NMR) and proton nuclear magnetic resonance (1H-NMR) spectroscopies. The results showed that when carrying out the reaction at high temperature (from 90 °C to 120 °C) and CO2 pressure (60–120 psi), the reaction’s conversion improves; however, the selectivity of the reaction decreases due to the promotion of side reactions. Regarding the catalyst, increasing the TBAB concentration from 2.0 to 5.0 w/w% favors selectivity. The presence of a secondary mechanism is based on the formation of a carboxylate ion, which was formed due to the interaction of CO2 with the catalyst and was demonstrated through 13C-NMR and FT-IR. The combination of these factors makes it possible to obtain the largest conversion (96%), carbonation (95%), and selectivity (99%) values reported until now, which are obtained at low temperature (90 °C), low pressure (60 psi) and high catalyst concentration (5.0% TBAB).

Phase Equilibria of the Synthesized Ternary CH4/CO2/N2 Mixed-Gas Hydrates in Tetrabutylammonium Bromide Aqueous Solutions at Different Concentrations

Hydrate-based gas separation (HBGS) technology can effectively separate CH4 and CO2 in multicomponent gases. To provide the necessary basic data for the HBGS technology, the hydrate phase equilibrium conditions of a ternary gas mixture (CH4/CO2/N2 = 0.5/0.4/0.1) were determined and compared in tetrabutylammonium bromide (TBAB) aqueous solutions with different mass fractions (0.05, 0.1, 0.2, and 0.4). The results indicated that all four concentrations of TBAB aqueous solution could shift the hydrate phase equilibrium conditions of the ternary gas mixture to higher temperatures and lower pressures; this influence was enhanced with higher TBAB concentrations. When the TBAB mass fraction was 0.4, under the same phase equilibrium pressure conditions, the phase equilibrium temperature increased by a range of approximately 9–14 K compared with that of a pure water system. Meanwhile, TBAB had a greater impact on the phase equilibrium conditions of hydrates containing larger proportions of CO2 and CH4 gas and a greater impact on the phase equilibrium conditions of CO2 and CH4 gas hydrates than on N2 hydrate.

Tetrabutylammonium bromide assisted preparation of monodispersed submicrometer silica particles

In this work, we demonstrate a new, facile approach for preparation of monodispersed, submicrometer silica particles via a tetrabutylammonium bromide (TBABr) assisted Stöber method. Sizes of the resulting silica particles increased from 0.39 to 1.08 μm with polydispersity lower than 5 % while the concentration of TBABr in the reaction media was elevated from 0 to 20.0 mM. The presence of TBABr molecules was able to effectively suppress the condensation rate of silanol monomers during the Stöber reaction, which, in turn, slowed the formation of silica seeds and thus accounted for growth of large silica particles. The use of tetraethylammonium bromide (TOABr), a quaternary ammonium agent with longer alkyl chains, instead of TBABr, yielded monodisperse silica particles more hydrophobic in character, making it feasible to tailor the surface properties of the as-prepared silica particles.

Effect of Electric Current on the Wettability of Carbon-Containing Gas Diffusion Electrodes by Aqueous Solutions and the Change in Their Capacitance Characteristics

We study the effect of the treatment by an electric current of two-layer gas diffusion electrodes made of porous (66–68 vol %) composite material based on A-437E acetylene black and polytetrafluoroethylene. Polarization is carried out cyclically in the range 0.0 ± 2.0 V by anodic and cathodic currents, respectively, in 1 M H2SO4 and 0.5 M KOH with the addition of tetrabutylammonium bromide (TBAB). In both cases, the increase in the charge passed leads to an increase in the volume of electrolyte pores and the electrical capacitance of the electrodes. Under anodic polarization, the increase in the wettability and capacitance of the electrodes is larger than under the cathodic process; however, in the latter case, the carbon surface does not undergo oxidation. As the charge passed and the TBAB concentration increases, the ohmic loss grows. The possible causes of the observed phenomena are considered.

Kinetic investigations of styrene carbonate synthesis from styrene oxide and CO2 using a continuous flow tube-in-tube gas-liquid reactor

A continuous method of styrene carbonate (SC) synthesis from styrene oxide (SO) and carbon dioxide (CO2) is reported, using a semipermeable Teflon® AF-2400-based tube-in-tube gas-liquid reactor. The reaction was performed in the presence of and tetrabutylammonium bromide (TBAB) and zinc bromide (ZnBr2), acting as a highly efficient and economical homogeneous binary catalyst system. The exceptionally high permeation of CO2 through the membrane, combined with the high surface area to volume ratio in such continuous flow reactors resulted in complete SO conversion (100%) in a significantly reduced reaction time (tR) of 45 min at 120 °C and 6 bar of CO2 pressure. The effect of various operating conditions such as reaction temperature, CO2 pressure, residence time and catalyst molar ratio (ZnBr2/TBAB) was determined. Moreover, a detailed kinetic study of SC synthesis was carried out to determine the corresponding kinetic values (k and Ea) and activation parameters (ΔH‡, ΔS‡ and ΔG‡). Based on the experimental data, the reaction was found to be first-order in SO, TBAB and CO2 concentrations. The activation energy of SC synthesis in the presence of TBAB catalyst alone was calculated to be 55 kJ mol−1 over a temperature range of (90–120 °C), which was reduced to 32 kJ mol−1 as a result of using ZnBr2 as a co-catalyst.

A novel ion-exchange strategy for the fabrication of high strong BiOI/BiOBr heterostructure film coated metal wire mesh with tunable visible-light-driven photocatalytic reactivity

Visible-light-driven (VLD) BiOI/BiOBr heterostructure films with hierarchical microstructure have been firstly fabricated on 304 stainless steel wire mesh (304SSWM) substrates through a novel ion-exchange method using the BiOI film as precursor. The concentration of tetrabutylammonium bromide (TBAB) is the key factor to control the composition and microstructure of BiOI/BiOBr films. Physical, chemical, and optical properties of BiOI/BiOBr heterostructure films were characterized by X-ray diffraction, scanning electron microscope, energy-dispersive X-ray spectroscopy, high resolution transmittance electron microscopy, X-ray photoelectron spectroscopy, UV–vis diffuse reflectance absorption, and fluorescence spectrophotometer, respectively. The VLD photocatalytic ability of the BiOI/BiOBr heterostructure film coated 304SSWM was studied by degrading rhodamine B and pIRES2-EGFP plasmid as target water organic pollutants and pathogenic bacteria genetic materials. The BiOI/BiOBr heterostructure film coated 304SSWM fabricated with 50 mM TBAB has excellent photocatalytic activity, stability, and reusability in the cycled experiments. The reasons for these unique features can be ascribed to the formation of heterojuction structure and the open framework structure of the 304SSWM. The current work can provide new strategies to construct novel VLD photoactive functional films for water purification and disinfection.

Carbonation of Epoxidized Methyl Soyates in Tetrabutylammonium Bromide-Based Deep Eutectic Solvents.

Carbonated methyl soyates have been successfully prepared by cycloaddition of carbon dioxide (CO2) to epoxidized methyl soyates in tetrabutylammonium bromide (TBAB)-based deep eutectic solvents (DES). Experimental parameters, i.e., reaction temperature, reaction time, CO2 pressure and TBAB concentration were evaluated. The different reaction conditions have a significant influence on the yields of carbonated methyl soyates. The use of TBAB-based DES (tetrabutylammonium bromide/triethylene glycol) significantly shortened the reaction time of the cycloaddition of CO2 to epoxidized methyl soyates. FT-IR and NMR analysis indicated that 95% of the yield of the five-membered cyclic carbonated methyl soyates were obtained at 120°C with 1.0 MPa pressure of CO2.

Hydrate Equilibrium Measurements for CH4, CO2, and CH4 + CO2 in the Presence of Tetra-n-butyl Ammonium Bromide

In this paper, hydrate phase equilibrium data for the CH4/CO2 + water system, CH4 + tetrabutylammonium bromide (TBAB) + water system, CO2 + TBAB + water system, and CH4/CO2 + TBAB + water system were measured at temperature ranged from 273.6 to 294.2 K and pressure ranged from 0.54 to 14.57 MPa with the 1.76 and 14.00 mass fraction of TBAB solutions. The mixture gas hydrate formation equilibrium temperature and pressure were tested by an isochoric pressure-search method. The mixture gas were composed of 67.00 mol % CH4 and 33.00 mol % CO2. The experiment results show that at low TBAB concentration (1.76 wt %), TBAB solution have promote effect under low pressure (lower than 3 MPa), and have nonsignificant promote effect at high pressure. The phase equilibrium conditions for CH4/CO2 mixture gas hydrates with TBAB mainly were determined by the concentration of TBAB solution and did not rely on the concentration of CH4/CO2 mixture gas.

Determination of β-agonists in Porcine Meats by Ion-Pair Extraction and High Performance Liquid Chromatography

ABSTRACTIon-paired extraction was employed for the determination of salbutamol, clenbuterol, and ractopamine. Tetrabutylammonium bromide was used as the ion-pairing agent and water–acetonitrile was the extraction solvent. The concentration and pH of the buffer, salt addition, concentration of tetrabutylammonium bromide, and type and volume of extraction solvent were optimized. No centrifugation step was required. Matrix interferences from real samples were eliminated using matrix-matched calibration. Under the optimum conditions, a linear calibration relationship was present from 0.0025 to 3 µg mL−1 with an enrichment factor of more than 25. This method was combined with high-performance liquid chromatography for the determination of β-agonists in porcine meats with low limits of detection, high recovery, and rapid analysis.

Synthesis of Cyclic Carbonates Catalysed by Aluminium Heteroscorpionate Complexes.

New aluminium scorpionate based complexes have been prepared and used for the synthesis of cyclic carbonates from epoxides and carbon dioxide. Bimetallic aluminium(heteroscorpionate) complexes 9-14 were synthesised in very high yields. The single-crystal X-ray structures of 12 and 13 confirm an asymmetric κ(2)-NO-μ-O arrangement in a dinuclear molecular disposition. These bimetallic aluminium complexes were investigated as catalysts for the synthesis of cyclic carbonates from epoxides and carbon dioxide in the presence of ammonium salts. Under the optimal reaction conditions, complex 9 in combination with tetrabutylammonium bromide acts as a very efficient catalyst system for the conversion of both monosubstituted and internal epoxides into the corresponding cyclic carbonates showing broad substrate scope. Complex 9 and tetrabutylammonium bromide is the second most efficient aluminium-based catalyst system for the reaction of internal epoxides with carbon dioxide. A kinetic study has been carried out and showed that the reactions were first order in complex 9 and tetrabutylammonium bromide concentrations. Based on the kinetic study, a catalytic cycle is proposed.

Effect of TBAB/KCl on Constructing Anionic Wormlike Micelles

Using rheological measurements, we investigated the wormlike micelles formed by anionic surfactants, sodium oleate (NaOA), and sodium erucate (NaOEr) in the presence of KCl and tetrabutyl ammonium bromide (TBAB). The viscosity of the NaOA solution increased with KCl concentration, but adding TBAB decreased viscosity. In contrast, the apparent viscosity of NaOEr-KCl solution enhances with increasing TBAB concentration. In addition, NaOEr is better than NaOA at encouraging the construction of viscoelastic wormlike micelles, needing less surfactant and a lower salt concentration. We prepared a wormlike micelle system with strong viscoelasticity by using NaOEr, cooperatively induced by KCl and TBAB. Based on these studies, we discussed the complex influence of TBA+ on constructing wormlike micelles.

CO2 capture using semi-clathrates of quaternary ammonium salt: structure change induced by CO2 and N2 enclathration.

Semi-clathrates of tetrabutylammonium bromide (TBAB) are investigated for their potential application in the CO2 capture context based on hydrate technology. The three-phase lines of semi-clathrates of CO2-TBAB-H2O and N2-TBAB-H2O are established simultaneously with their structure using in situ Raman scattering performed at high pressure. The preferred crystal phase obtained at ambient pressure from solutions of 5 and 40 wt % TBAB initial concentrations is shown to change upon enclathration of CO2 or N2, or by applying a higher pressure on the system. Deep in the stability field, metastable hydrate phases are occurring at the onset of the formation and correspond to the ones expected under ambient pressure conditions. Depending on the pressure, they progressively transformed into the most stable ones when approaching equilibrium and dissociation points. Besides, it is shown that a 5 wt % TBAB original solution forms preferentially a mixed structure of both type B and type A at low gas pressure with CO2 as the guest gas. A new structure is spectroscopically characterized at pressures higher than ∼2 MPa CO2. Type A is demonstrated to be stable at 5 wt % initial TBAB concentration with N2 as the guest molecule and pressure between 8 and 12 MPa. These structural data address new insights on the relationship between the hydrophilic-anion and hydrophobic-cation intercalation with a guest gas producing hydrophobic interaction in a distorted water lattice.

Recovery of Levafix brilliant red E-4BA and Levafix brilliant red E-6BA from aqueous solution by supported liquid membrane

The transport and recovery of Levafix brilliant red E-4BA and Levafix brilliant red E-6BA were investigated using polytetrafluoroethylene (PTFE) fiber based supported liquid membrane containing tetra butyl ammonium bromide (TBAB) in coconut oil as a carrier. The influencing parameters studied are: pH of the feed solution, concentration of dye in the feed solution, extractant concentration, and various kind of stripping agent, rate of stirring, time of transport, reusability of membrane and stability of membrane. Increase in TBAB concentration inside the membrane enhances the flux with its maximum value at <TEX>$1.553{\times}10^{-4}$</TEX> M TBAB. Further increase in the concentration of TBAB leads to decreased rate of transport due to increase in viscosity of membrane liquid. The optimum conditions for dye transport are: pH of feed (<TEX>$7{\pm}0.1$</TEX>), <TEX>$1.553{\times}10^{-4}$</TEX> M extractant concentration, 350 rpm for stirring, <TEX>$4.9{\times}10^{-1}$</TEX> M potassium hydrogen phthalate as a stripping solution, the time of transport 6 h. It was noticed that flux values were increased with increasing dye concentration in the feed phase. Applying this study to textile wastewater, dyes were transported up to 98% in 6 h. This recovery technique is rewarding to environment and economic.

Adsorption behavior of the ternary system of phospholipid 1-palmitoyl-2-oleoyl-sn-gylycero-3-phosphocholine in 3-hydroxypropionitrile with added tetrabutyl ammonium bromide

The adsorption behavior in a ternary system composed of the non-ionic surfactant POPC (1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine) and the ionic surfactant TBABr (tetrabutyl ammonium bromide) in the polar solvent HPN (3-hydroxypropionitrile) is investigated utilizing surface tension measurements and ARXPS (angular resolved X-ray photoelectron spectroscopy). The latter technique allows evaluating the surface excess of both surfactants. The combined experimental information (i.e. surface excess and surface tension) allows the determination of the chemical potential and thus the activities of both surfactants by virtue of the Gibbs equation. While the activity coefficient of TBABr is hardly affected by the presence of POPC, the activity coefficient of POPC strongly depends on both, the concentration of POPC and the concentration of TBABr. We observe the activity coefficient fPOPC to vary by more than 3 orders of magnitude in the 2-dimensional parameter space (cPOPC, cTBABr). This finding reflects and explains the surprising behavior of the surface tension: adding TBABr to the binary system POPC/HPN may increase or decrease the surface tension, depending on the POPC concentration. Inspection of these results suggests that mixed POPC/TBABr aggregates are formed at low POPC concentrations while the typical features of micelle formation are absent in this ternary system even at very low TBABr concentration.

Use of bulk liquid membrane for the removal of Cibacron Red FN-R from aqueous solution using TBAB as a carrier

The transport of Cibacron Red FN-R anionic dye through a methylene chloride bulk liquid membrane (BLM) containing a tetra butyl ammonium bromide (TBAB) as an excellent carrier was studied. The extracted dye simultaneously stripped into aqueous stripping solution. The basic fundamental parameters were determined. These include pH of the feed, nitric acid concentration in the strip solution, TBAB concentration in the membrane phase, initial dye concentration in the feed phase and rate of stirring. The transport efficiency of dye increased with increasing carrier concentration from 6.06±0.1×10−6 to 3.85±0.1×10−4M. The transport study was highly selective for anionic dye and efficiency of transport was not affected by the presence of electrolytes such as sodium chloride and sodium sulphates in feed solution. The percentage of dye transported across the liquid membrane after 70min, was 95±0.1%. When the optimum parameters were used for real textile dyeing effluent for recovery of dyes, the results were found to be satisfactory.

Vapour–liquid equilibrium relationship between toluene and mixed surfactants

Micellar partitioning of volatile organic compounds (VOCs) in surfactant solutions and its effects on vapour–liquid equilibrium is fundamental to the overall design and implementation of surfactant-enhanced remediation. Knowledge of the vapour–liquid equilibrium partitioning coefficients for VOCs, especially in contaminated soils and groundwater in which they exist, is required. Headspace experiments were performed to quantify the effect of three mixed surfactants, cetyltrimethyl ammonium bromide (CTMAB) with tetrabutylammonium bromide (TBAB), sodium dodecyl sulph ate (SDS) with Triton X-405 (TX405), and CTMAB with Triton X-100 (TX100), on the apparent Henry's constants (H c ) of toluene at temperatures ranging from 25 °C to 40 °C. The H c values were significantly reduced in the presence of all three mixed surfactants at concentrations above their critical micelle concentrations (CMC). Mixed micellar partitioning, showing effects on the vapour–liquid equilibrium of toluene, was primarily responsible for the significant reduction of H c in their mixed systems. The mixed surfactants CTMAB–TX100 had the greatest effect on H c above the CMC, followed by SDS–TX405, then CTMAB–TBAB. Mixed systems of CTMAB–TX100 decreased H c at concentrations significantly lower than the SDS–TX405 and CTMAB–TBAB concentrations, because of to the lower CMC of CTMAB–TX100. Vapour–liquid equilibrium data were also tested against the model (H c =H/(1+K(X−CMC)) that described the partitioning of VOCs in vapour–water–micelle phases. The correlation of H c with mixed surfactant concentrations (X) and CMC can be utilized as an effective tool to predict the H c by mixed surfactants.

High performance liquid chromatography for the simultaneous analysis of penicillin residues in beef and milk using ion-paired extraction and binary water–acetonitrile mixture

An ion-paired extraction (IPE) has been developed for the analysis of penicillin antibiotics (penicillin G, oxacillin and cloxacillin) in beef and milk samples using tetrabutylammonium bromide (TBABr) as ion-pairing agent and binary water–acetonitrile as extractant. The factors affecting the IPE efficiency were optimized including solution pH, volume of acetonitrile (ACN), concentration of TBABr and electrolyte salt (NH4)2SO4. The optimum IPE conditions were 10mmolL−1 phosphate buffer pH 8, 2mL of ACN, 6mmolL−1 of TBABr and 2.5mL of saturated ammonium sulfate. Under the HPLC condition: an Xbridge™ C18 reversed-phase column, isocratic elution of 5mmolL−1 phosphate buffer (pH 6.6) and acetonitrile (75:25, v/v) and a flow rate of 1mLmin−1, with UV detection at 215nm, the separation of three penicillins was achieved within 10min. Under the selected optimum conditions, the enhancement of 21–53 folds compared to that without preconcentration and limits of detection (LODs) of 1–2ngmL−1 were obtained. Good reproducibility was achieved with RSD<2% for retention time and <5% for slope of calibration curves. The average recoveries higher than 85% were obtained. The proposed IPE-HPLC method has shown to be high efficient preconcentration and analysis method for penicillin residues in beef and milk with LOD lower than the maximum residue limits.

New accelerated method of impregnation by aqueous electrolyte of carbon black gas-diffusion electrodes to study their structural and electrochemical characteristics

A new method of fast impregnation of carbon black gas-diffusion hydrophobized electrodes is suggested under their cathodic polarization in an alkaline aqueous solution of tetrabutylammonium bromide (TBAB) at the potentials of hydrogen evolution. As dependent on the quantitative content of polytetrafluoroethylene (PTFE) in the electrode, current density, time, TBAB concentration, various degree of electrode wetting is observed, up to nearly complete electrode flooding in just several hours. When electrodes are stored, their original electrolyte porosity is not recovered. the electrode with 8 wt % of PTFE was used to show the effect of the electrode flooding degree on the double layer capacity, average diameter of electrolyte pores, their surface area and activity in the case of oxygen reduction. This method may be used for simulation of the process of flooding of gas-diffusion electrodes by electrolyte in the course of their prolonged operation.

Hierarchical construction of PbS architectures based on the adsorption and sustained release of H 2S by TBAB

Multi-arm PbS architectures were successfully synthesized in high yield by a facile hydrothermal process at 90 °C for 48 h, employing lead nitrate (Pb(NO 3) 2) and thioacetamide (TAA) as precursors. A new surfactant: tetrabutyl ammonium bromide (TBAB), was used in this process. The as-prepared PbS products are characterized by X-ray powder diffraction (XRD), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and Fourier transform infrared (FT-IR) spectroscopy. The results showed that the concentration of TBAB, as well as the molar ratio of Pb(NO 3) 2 to TAA are crucial factors on the morphologies and sizes of the hierarchical PbS microcrystals. A reasonable possible new formation mechanism of hierarchical PbS structures based on the adsorption and sustained release of H 2S by TBAB has been presented.