Octyl Trimethyl Ammonium Research Articles

Switching Hydrophobic Interface with Ionic Valves for Reversible Zinc Batteries.

Developing hydrophobic interface has proven effective in addressing dendrite growth and side reactions during zinc (Zn) plating in aqueous Zn batteries. However, this solution inadvertently impedes the solvation of Zn2+ with H2O and subsequent ionic transport during Zn stripping, leading to insufficient reversibility. Herein, an adaptive hydrophobic interface that can be switched "on" and "off" by ionic valves to accommodate the varying demands for interfacial H2O during both the Zn plating and stripping processes, is proposed. This concept is validated using octyltrimethyl ammonium bromide (C8TAB) as the ionic valve, which can initiatively establish and remove a hydrophobic interface in response to distinct electric-field directions during Zn plating and stripping, respectively. Consequently, the Zn anode exhibits an extended cycling life of over 2500 h with a high Coulombic efficiency of ≈99.8%. The full cells also show impressive capacity retention of over 85% after 1000 cycles at 5 A g-1. These findings provide a new insight into interface design for aqueous metal batteries.

Effective Removal of Ibuprofen from Aqueous Solution Using Cationic Surface-Active Agents in Dissolved Air-Flotation Process

This research paper focuses on the removal of the nonsteroidal anti-inflammatory drug, ibuprofen, from an aqueous solution using a dissolved air flotation process. The comparison of different types of cationic surface-active agents such as cetyltrimethyl ammonium bromide (CTAB), tetrabutyl ammonium bromide (TBAB), and octyltrimethyl ammonium bromide (OTAB) have been employed to scrutinize the effective removal of the ecotoxic pharmaceutically active compound. The work included the influencing parameters such as pressure, contact time, surfactant dosage, pH, flow rate, and initial concentration owing to the best-optimized conditions. The maximum removal rate of 96.09% was achieved at 15 min for CTAB, TBAB had 62.36% at 45 min, and 89.6% was obtained for OTAB at 30 min, with 50 mg L−1 as the initial concentration and pH = 4. The removal rate was better with the optimized dosage of CTAB at 0.6 g, TBAB at 1.2 g, and OTAB at 1.0 g. It was observed that the geometric shape of the surface-active agents had greater impacts on the contaminants’ efficiency. CTAB and OTAB were combined to find out the best possible removal rate of contaminants. The synergistic effect augments surfactant-based occurrence to be better in forming a good foaming effect and tends to have a lower critical micelle concentration (CMC). From the evaluation of kinetic models, pseudo-second-order flotation kinetics fitted the experimental data best. Furthermore, the formed metabolites that had been identified using gas chromatography-mass spectrometry were found to be less toxic than the parenting compounds.

Potentiometric Study of Carbon Nanotube/Surfactant Interactions by Ion-Selective Electrodes. Driving Forces in the Adsorption and Dispersion Processes.

The interaction (adsorption process) of commercial ionic surfactants with non-functionalized and functionalized carbon nanotubes (CNTs) has been studied by potentiometric measurements based on the use of ion-selective electrodes. The goal of this work was to investigate the role of the CNTs’ charge and structure in the CNT/surfactant interactions. Non-functionalized single- (SWCNT) and multi-walled carbon nanotubes (MWCNT), and amine functionalized SWCNT were used. The influence of the surfactant architecture on the CNT/surfactant interactions was also studied. Surfactants with different charge and hydrophobic tail length (sodium dodecyl sulfate (SDS), octyltrimethyl ammonium bromide (OTAB), dodecyltrimethyl ammonium bromide (DoTAB) and hexadecyltrimethyl ammonium bromide (CTAB)) were studied. According to the results, the adsorption process shows a cooperative character, with the hydrophobic interaction contribution playing a key role. This is made evident by the correlation between the free surfactant concentration (at a fixed [CNT]) and the critical micellar concentration, cmc, found for all the CNTs and surfactants investigated. The electrostatic interactions mainly determine the CNT dispersion, although hydrophobic interactions also contribute to this process.

Interconnected polyaniline nanostructures: Enhanced interface for better supercapacitance retention

Polyaniline and its nanocomposites have emerged as desirable electrode materials for supercapacitors. However, achieving specific capacitance with long-term cyclic stability is still a challenge. The present study reports on novel hierarchically porous and cross-linked polyaniline synthesized by a method employing aniline (monomer) and phytic acid (dopant acid) in the presence of octyltrimethyl ammonium bromide (OTAB) surfactant. The electrochemical performance of the phytic acid doped sample has been compared with HCl doped samples, the former being superior, i.e., a specific capacitance of 523 and 325 F g-1 at current densities of 0.25 and 10 A g-1, respectively. Additionally, the same possess excellent cycling stability with retention of ~88% of its initial capacitance over 10,000 charge-discharge cycles. Further, the phytic acid doped sample exhibited a lower equivalent series resistance (0.98 Ω cm2) than the HCl doped sample (1.26 Ω cm2). These results reveal the capability of the phytic acid doped hierarchical polyaniline sample as a promising active material for electrochemical applications.

Promising Route for the Development of a Computational Framework for Self-Assembly and Phase Behavior Prediction of Ionic Surfactants Using MARTINI.

Surfactants are amphiphilic molecules with multiple uses and industrial applications as detergents, wetting agents, emulsifiers, and so forth. They can be divided into three main categories: nonionic, ionic, and zwitterionic. The development of a universal computational framework able to predict key properties such as their critical micelle concentration (cmc) and the size of the micelles they form and to ultimately extract phase diagrams for their aqueous solutions, possibly in the presence of salts and oils, using their chemical constitution as input, would provide valuable information for the design and the production of these materials. In this work, we focus on ionic surfactants and investigate a possible route toward the development of such a framework based on coarse-grained simulations using the MARTINI forcefield in two versions: its implicit solvent version, called Dry MARTINI, and its explicit solvent version, called Wet MARTINI. The surfactants considered in our efforts are the anionic sodium dodecyl sulfate (SDS) and the three cationic cetyl, dodecyl, and octyl trimethyl ammonium bromide (CTAB, DTAB, and OTAB, respectively). First, we choose their mapping onto coarse-grained MARTINI beads. Next, we estimate their cmc's, their peak aggregation numbers, Nagg, and in the case of SDS, its small angle neutron scattering pattern at low concentrations, applying the Dry MARTINI forcefield. With a single modification to the Lennard-Jones energy parameter between hydrophobic beads and invoking Ewald summation with a physically meaningful dielectric constant for electrostatic interactions, our estimates are in very good agreement with experimental results. Furthermore, we predict the phase behavior of SDS/water and CTAB/water binary solutions using Wet MARTINI and find semiquantitative agreement with experimental phase diagrams. We conclude that the MARTINI forcefield, with careful treatment of electrostatic interactions and appropriate modification of parameters for some key functional groups, can be a powerful ally in the quest for a universal computational framework for the design of new surfactants with improved properties.

Novel eco-friendly ionic liquids to solubilize seven hydrophobic pesticides

In line with the requirements of green chemistry, the preparation of eco-friendly pesticide formulations has become an inevitable development trend. In this work, we explored the feasibility of four new ionic liquids (ILs, [Octyl trimethyl ammonium] anions, anions = proline, valine, leucine, tartaric acid) as environmentally-friendly solvents for pesticide emulsifiable concentrates, and also as alternatives to traditional imidazole-based ILs since they do not contain the imidazole ring and the anions are natural substances. The results showed that the solubility of pesticides (clethodim, metolachlor, acetochlor, prochloraz, thiamethoxam, glyphosate, acetamiprid) in water with 25%w/v ILs was significantly improved, especially for acetamiprid, where the solubility was increased 19-fold, while it only increased about 4 to 5-fold after adding imidazole-based ILs in our previous work. In addition, the solubilization mechanism was explored by many methods and found that the solubilization effect does not completely depend on the critical micelle concentration (CMC) value but has a great relationship with the hydrophilicity of the ILs which may affect the size of micelles and release behavior to pesticides. Finally, 1H NMR was used to investigate the solubilization sites of ILs for glyphosate, and the interaction between pesticides and anions was explored by the quantum chemical method.

The adsorption characteristics of fluoride on commercial activated carbon treated with quaternary ammonium salts (Quats)

Commercial activated carbon was treated with six quaternary ammonium salts (Quats), namely, hexyltrimethylammonium (HTMA), octyltrimethylammonium (OTMA), decyltrimethylammonium (DCTMA), dodecyltrimethylammonium (DDTMA), Tetradecyltrimethylammonium (TDTMA), and hexadecyltrimethylammoium (HDTMA) as to enhance the fluoride adsorption capacity. In batch mode experiments, fluoride adsorption onto the Quats-treated activated carbon decreased dramatically with increase in solution pH. Fluoride removal by the Quats-treated activated carbons was closely related to the Quats chain length at less-than critical micelle concentration (CMC). Multi-site adsorption isotherm described fluoride adsorption characteristics well. Results showed that activated carbon treated with DDTMA exhibited the best fluoride adsorption density among all Quats investigated. DDTMA-treated activated carbons exhibited two-fold increase in the fluoride adsorption capacity compared to the untreated activated carbon. Results of regeneration, by alkaline desorption and/or Quats re-loading, showed fluoride-laden activated carbons have high reusability. DDTMA increased the positive surface charge of the activated carbon that enhanced fluoride adsorption. DDTMA-treated activated carbon was promising for fluoride removal from water with much enhanced removal capacity.

One-pot synthesis of SiO2@SiO2 core-shell microspheres with controllable mesopore size as a new stationary phase for fast HPLC separation of alkyl benzenes and β-agonists.

Monodisperse SiO2@SiO2 core-shell silica microspheres (CSSM) with enlarged mesopores perpendicular to the particles surface were prepared using a dual-templating approach. With cetyltrimethyl ammonium bromide as the template and octyltrimethyl ammonium bromide as an auxiliary chemical, the pore size can be enlarged from 2.6 to 10.6nm. The average shell thickness can be increased from 31nm to 97nm by adjusting the concentrations of the surfactants under continuous addition of tetraethyl orthosilicate. After coating twice, the resulting CSSM has a uniform mesoporous shell of about 198nm thickness and a narrow pore size distribution. The CSSM were then modified with octadecyltrichlorosilane to give a material referred to as CS-C18. It was evaluated by separating the mixture of methylbenzene (toluene), ethylbenzene, n-propylbenzene, n-butylbenzene, n-amylbenzene and hexylbenzene. The baseline separation of the six alkyl benzenes is achieved within 2min. Compared to a commercial column of type BEH-C18, CS-C18 shows a faster and better separation even at lower back pressure. It was also applied to the fast separation of benzo[a]pyrene, salbutamol, ractopamine and clenbuterolin residues in pork samples. The high column efficiency and better reproducibility suggest that the CSSM can be used as a matrix for fast separation and analysis of several kinds of small analytes. Graphical abstract A dual-templating approach was utilized to produce the core shell microsphere with controllable mesopore channels by using hexadecyltrimethylammonium bromide (CTAB) as the template and trioctylmethylammonium bromide (TOMAB) as an auxiliary chemical to enlarge the size of CTAB micelles.

Detecting wormlike micellar microstructure using extensional rheology

We report experiments on two series of wormlike micellar solutions that comprise octyl trimethylammonium bromide/sodium oleate (OTAB/NaOA) and cetylpyridinium chloride/sodium salicylate (CPCl/NaSal) using a capillary breakup extensional rheometer (CaBER) and a dripping onto substrate (DoS) technique. These wormlike micellar systems show a peak in zero shear viscosity or in the shear relaxation time beyond a critical surfactant or salt concentration. Prior cryogenic transmission electron microscopy imaging has indicated that the system based on OTAB/NaOA experiences a transition from linear to shorter linear micelles (L-L) beyond the viscosity peak. However, the linear wormlike micelles based on CPCl/NaSal form branched networks beyond the viscosity peak (L-B). In this work, we investigate whether the extensional rheology is sensitive to these two different microstructural transitions. In particular, we attempt to develop a criterion based on the extensional flow parameters in order to distinguish these two systems from each other. In addition, we probe the possibility of flow-induced micellar breakage imposed by capillary breakup extensional experiments. Our results indicate that at a given zero shear viscosity, the branched wormlike micelles based on CPCl/NaSal exhibit a longer filament lifetime tfil than the linear wormlike micelles. However, beyond the critical concentration, the linear wormlike micelles based on OTAB/NaOA exhibit significantly shorter filament lifetimes than their linear counterparts at concentrations below the viscosity peak. More importantly, we show that the filament lifetime scales differently with zero shear viscosity η0 in these two systems. For L-B transition, tfil∝η01.1 below the viscosity peak and tfil∝η00.76 above the viscosity peak. However, for L-L transition, this scaling remains the same for concentrations below and above the viscosity peak and reads as tfil∝η00.5. These findings provide a novel criterion to distinguish these two types of microstructural transitions in wormlike micelles. On the other hand, we demonstrate that the Trouton ratio, filament lifetime, and the extensional relaxation time measured by CaBER technique are all lower than the ones obtained by DoS method. The latter result provides the first evidence for strong nonlinear effects (e.g., flow-induced micellar breakage) in capillary breakup extensional flows of wormlike micelles.

Synthesis, structure, and host-guest properties of an anthracene-based macrocyclic arene

A new anthracene-based macrocyclic host (H) was designed and synthesized. H has a molecular box-type structure with a flexible cavity. It exhibits highly strong binding affinities towards selected cationic model guests, butyl viologen (BV), dibutylammonium (DBA), and octyltrimethylammonium (OTMA). For example, the association constant of H and BV is up to (2.2 ± 0.3) × 107 M−1; it is interesting to observe host-guest charge-transfer band (and color change) and fluorescence quenching of H’s anthracene unit due to the formation of inclusion complex.

Tetrodotoxin, Epinephrine, and Chemical Permeation Enhancer Combinations in Peripheral Nerve Blockade.

Chemical permeation enhancers (CPEs) have the potential to improve nerve blockade by site 1 sodium channel blockers such as tetrodotoxin (TTX). Here, we investigated the efficacy and toxicity of CPE-enhanced nerve blockade across a range of TTX concentrations using 2 CPEs (sodium octyl sulfate and octyl trimethyl ammonium bromide). We also tested the hypothesis that CPEs could be used to reduce the concentrations of TTX and/or of a second adjuvant drug (in this case, epinephrine) needed to achieve prolonged local anesthesia METHODS:: Sprague-Dawley rats were injected at the sciatic nerve with combinations of TTX and CPEs, with and without epinephrine. Sensory and motor nerve blockade were assessed using a modified hot plate test and a weight-bearing test, respectively. Systemic and local toxicities of the different combinations were assessed. Addition of increasing concentrations of TTX to fixed concentrations of CPEs produced a marked concentration-dependent improvement in the rate of successful nerve blocks and in nerve block duration. CPEs did not affect systemic toxicity. At some concentrations, the addition of sodium octyl sulfate increased the duration of block from TTX plus epinephrine, and epinephrine increased that from TTX plus CPEs. The addition of epinephrine did not cause an increase in local toxicity, and it markedly reduced systemic toxicity. CPEs can prolong the duration of nerve blockade across a range of concentrations of TTX. CPEs could also be used to reduce the concentration of epinephrine needed to achieve a given degree of nerve block. CPEs may be useful in enhancing nerve blockade from site 1 sodium channel blockers.

A comparison of linear and branched wormlike micelles using large amplitude oscillatory shear and orthogonal superposition rheology

In this study, we present a comparative investigation of linear and branched wormlike micelles using two nonlinear rheological tools: orthogonal superposition rheology and large amplitude oscillatory shear (LAOS) rheology. The surfactants were a series of mixtures of octyl trimethyl ammonium bromide (C8TAB) and sodium oleate (NaOA). A transition from linear to branched wormlike micelles was obtained by either varying the relative ratio of NaOA to C8TAB at a fixed total surfactant concentration or by fixing the ratio of NaOA to C8TAB and varying the total surfactant concentration. Orthogonal superposition rheology imposes a small amplitude oscillatory shear strain over an orthogonally imposed shear flow to probe the effect of shear on the storage and loss modulus of the fluid. For both the linear and branched wormlike micelle solutions, the plateau modulus, the relaxation times, and the dynamic viscosity were all found to be sensitive to the strength of the orthogonally imposed shear rate. However, the non...

The Interaction between Reactive Dye and Octyl Trimethyl Ammonium Chloride

Octyl trimethyl ammonium chloride (OTMAC) is a very efficient accelerant for reactive dyes on dyeing silk. In order to understand the accelerating mechanism, the interaction between dye molecules and OTMAC molecule was studied in this paper. The results showed that the DTMAC made the dye molecules assembled and the particle size of dye assemblages could reach to more than 500nm. The assembling of dye molecules leads to increase of the maximum absorption wavelength of dye. The higher the temperature is, the weaker the interaction between dye molecule and accelerant.

Topical Drug Formulations for Prolonged Corneal Anesthesia

Ocular local anesthetics currently used in routine clinical practice for corneal anesthesia are short acting and their ability to delay corneal healing makes them unsuitable for long-term use. In this study, we examined the effect of the site 1 sodium channel blocker tetrodotoxin (TTX) on the duration of corneal anesthesia, applied with either proparacaine (PPC) or the chemical permeation enhancer octyl-trimethyl ammonium bromide (OTAB). The effect of test solutions on corneal healing was also studied. Solutions of TTX, PPC, and OTAB, singly or in combination, were applied topically to the rat cornea. The blink response, an indirect measure of corneal sensitivity, was recorded using a Cochet-Bonnet esthesiometer, and the duration of corneal anesthesia was calculated. The effect of test compounds on the rate of corneal epithelialization was studied in vivo after corneal debridement. Combination of TTX and PPC resulted in corneal anesthesia that was 8 to 10 times longer in duration than that from either drug administered alone, whereas OTAB did not prolong anesthesia. The rate of corneal healing was moderately delayed after coadministration of TTX and PPC. Coadministration of TTX and PPC significantly prolonged corneal anesthesia, but in view of delayed corneal reepithelialization, caution is suggested in the use of the drug combination.

Dyeing Acceleration Theory of Molecule Companion on Silk with Reactive Dyes

In this paper, a novel high efficient dyeing acceleration theory of molecule companion(DATMC) on silk with reactive dyes was invented and studied. Organic cations were used as accelerants to company reactive dyes to dye on silk, and the dyed silk was washed with anionic surfactant. The results showed that the dye-uptake rates were very high, nearly 100%. But if the carbon atom number of hydrophobic hydrocarbon chain of organic cation was equal to or more than 12, the organic cation would affect the fixation reaction of reactive dye on silk. On the contrary, if it was equal to or less than 8, the fixation reaction would be accelerated. The fixation rates were 98.10% and 98.48% with octyl trimethyl ammonium bromide(OTAB) and hexyl butyl dimethyl ammonium bromide(HBDAB) as accelerants, respectively. The fastnesses of dyed silk were 4-5, and the silk could be dyed uniformly if the accelerant was added in several times.

Stabilization of a hydrophobic natural dye by intercalation into organo-montmorillonite

The stability of the naturally occurring annatto dye against irradiation with visible light was enhanced by intercalation into octyl trimethylammonium and dodecyl trimethylammonium montmorillonite. The intercalated dye exhibited improved light fastness. The effect of the stability enhancement was more distinct with dodecyl trimethylammonium montmorillonite. The reason of the improvement was proved to be the hindrance from the contact with the atmospheric oxygen because the dye molecules were incorporated in the interlayer space. The amount of the adsorbed dye could be increased more than ten times when an aqueous ethanolic solution was used instead of pure ethanol as solvent in the adsorption process.

Adsorption Kinetic Study of Reactive Dyes on Silk with Octyl Trimethyl Ammonium Bromide as Accelerant

The dyeing accelerating effect of octyl trimethyl ammonium bromide (OTAB) on dyeing silk with reactive red dye B-3BF, reactive yellow dye B-4RFN and reactive dark blue dye B-2GLN was studied in this paper. The dye-uptake rates increased with increasing concentration of OTAB, and the highest dye-uptake rates of three reactive dyes were 91~98%. The adsorption kinetics of dyeing process at different temperatures was also investigated by using pseudo first- and second-order kinetic models. The results showed that adsorption rates increased with increasing temperature. The adsorption kinetics of three reactive dyes on silk with OTAB as accelerant was found to follow the pseudo second-order sorption kinetics equation. The activation energy of reactive red dye B-3BF, reactive yellow dye B-4RFN and reactive dark blue dye B-2GLN dyeing on silk with OTAB as accelerant were found to be 26.91, 17.31, 6.99 kJ/mol, respectively.

Effect of cosolvents on the adsorption of ethofumesate by modified Moroccan bentonite and common clay

The adsorption of the slightly hydrophobic herbicide ethofumesate (Kow = 2.70) by a bentonite and a common clay from Morocco was studied in water and in the presence of different cosolvents (methanol, hexane and dissolved organic matter (DOM)). The bentonite (SC) and the clay (NSC) were used in both a raw and modified state by the addition of long-chain quaternary ammonium ions (tetramethylammonium TMA, octyl trimethylammonium OTMA and octadecyl trimethylammonium ODTMA). The Freundlich adsorption coefficients (Kf) of ethofumesate by TMA- and OTMA-clays in water increased significantly (8.5–93 fold (SC) and 2–12 fold (NSC)) in relation to raw clays. This was more evident for ODTMA-clays (1100 fold (SC) and 290 fold (NSC)). The adsorption capacities were lower for modified NSC and increased with the organic carbon content. Different interactions between adsorbate–solvent and adsorbate–adsorbent were established with cosolvents, but when they were present in the clay–water system a decrease in adsorption was seen in general. Adsorption decreased 4–7-fold (TMA-clays), 3.2-fold (OTMA-clays) and 2.4–2.8-fold (ODTMA-clays) in the presence of methanol. No significant change was seen in the adsorption by ODTMA-clays in presence of hexane, although a marked decrease occurred in this system for the adsorption by TMA-clays (no adsorption) and OTMA-clays (22-fold). No significant variation in adsorption was observed in the presence of DOM. The results indicated that the enhanced adsorption of ethofumesate by organic cation-exchanged clays in water can be significantly changed in the presence of different cosolvents. This has serious environmental implications for pesticide adsorption by modified bentonites and clays in the presence of organic solvents.

Ethylene adsorption on cationic surfactant modified zeolite NaY

The ethylene adsorption isotherms of zeolite NaY and their cationic surfactant modifiers, phenyl trimethyl ammonium bromide (PTAB), octyl trimethyl ammonium bromide (OTAB), hexadecyl trimethyl ammonium bromide (HTAB) and dioctadecyl dimethyl ammonium bromide (DDAB), were investigated. Zeolite NaY was synthesized and modified by cationic surfactants in the concentration range 0.1–3.0 mM. The ethylene adsorption isotherms indicated that only zeolite modified with PTAB could significantly enhance the ethylene adsorption capacity. Zeolite NaY modified with 0.5 mM PTAB was the best adsorbent and could adsorb up to 111.19 cm 3 g −1 of ethylene which was equivalent to a 28.5% increase. The XRD results indicate that modification of zeolite NaY with small amount of cationic surfactants does not change the crystallinity of the starting zeolite. The elemental analysis indicated that the Si/Al ratio of synthesized zeolite NaY was close to 2. Surface area characterization showed that the BET surface area and micropore surface area of modified zeolite slightly decreased but the external surface area, pore volume and pore size diameter remained unchanged.

Natural and modified clays from Morocco as sorbents of ionizable herbicides in aqueous medium

The capacities of two Moroccan clays, one of them swelling and the other non-swelling, as sorbents of three ionisable pesticides: terbutryn (basic), dicamba (anionic) and paraquat (cationic) were studied. Sorption was studied on natural and modified clays with three quaternary alkyl ammonium cations of different long-chain, octadecyltrimethylammonium (ODTMA), octyltrimethylammonium (OTMA) and tetramethylammonium (TMA). Freundlich or Langmuir models were used to obtain sorption parameters. Sorption of terbutryn and dicamba by ODTMA-clays was always higher than by natural clays. Distribution coefficients (Kd) of these modified clays increased 55–128-fold (terbutryn), and 1.4–8.6-fold (dicamba) respect to the natural clays. In contrast, sorption of terbutryn by the TMA-clays and of dicamba by TMA- and OTMA-clays was lower than for natural clays. Sorption coefficients of paraquat by natural clays were similar or higher than those obtained with modified clays. In general, the sorption of herbicides was higher by swelling clay than by non-swelling clay. The results point out that the Moroccan clays studied may be used as sorbents of cationic pesticides in their natural form and of basic or even anionic herbicides when modified with long-chain organic cations in barrier technologies to enhance the immobilization of herbicides and to prevent the contamination of surface and ground water.