Octadecyltrimethylammonium Chloride Research Articles

Extremely slow settling behavior of particles in dilute wormlike micellar fluid with broad spectrum of relaxation times

We selected a 1.4 wt% Octadecyl trimethyl ammonium chloride (OTAC) concentration wormlike micellar fluid with broad relaxation time spectrum and another single relaxation Maxwell fluid of 4.0 wt% OTAC concentration with a constant weight ratio of OTAC to NaSal of 5:1. The shear viscosity, dynamic modulus as well as the extensional viscosity were tested. The steady and unsteady motion of spheres were investigated by high-speed video images in these two wormlike micellar fluids. Extremely slow settling velocity is found when smaller spheres with diameters of 3.2 and 4.0 mm settles in the 1.4 wt% OTAC solution. Stronger rebound of these spheres occurs in this fluid. Comparing with particle settling velocity in inelastic power law fluid, we concluded that this extremely slow sedimentation in the 1.4 wt% OTAC solution seems to be dominated by the slowest stress relaxation of this solution. The rheology test demonstrated that this wormlike micellar fluid has more tensile hardening, low viscosity and strong elasticity. The oscillation of sphere results from the elasticity of the entangled microstructures of wormlike micelles. For a Maxwell viscoelastic 4.0 wt% OTAC solution, settling behaviors of spheres agree with previous literatures that the flow becomes instability as the Wi number exceeds a critical value.

Effect of the alkyl chain of quaternary ammonium cationic surfactants on corrosion inhibition in hydrochloric acid solution

In this study, the effect of the alkyl chain of quaternary ammonium cationic surfactants on corrosion inhibition in hydrochloric acid (HCl) solution was investigated by using dodecyl trimethyl ammonium chloride (DTAC), tetradecyl trimethyl ammonium chloride (TTAC), cetyl trimethyl ammonium chloride (CTAC), and octadecyl trimethyl ammonium chloride (OTAC) as corrosion inhibitors to uncover their structure–efficiency relationships. The effect of the alkyl chain of quaternary ammonium cationic surfactants on corrosion inhibition in HCl solution was studied under different conditions, such as corrosion inhibitor concentration, temperature, and acidity, and this was done using the weightlessness method. The results obtained show that these inhibitors have high corrosion inhibition effect on A 3 steel, and the corrosion inhibition efficiency is dependent on the length of the alkyl chain. At the same concentration, the longer the alkyl chain, the weaker the corrosion inhibition effect. When the temperature was 50 °C and the concentration of corrosion inhibitor was 70 mg/L, the corrosion inhibition efficiency order of the four cationic surfactants was DTAC > TTAC > CTAC > OTAC. Besides, the experimental results obtained show that the adsorption of the inhibitor on the A 3 steel surface conforms to the Langmuir type isotherm, and then the corresponding adsorption thermodynamic parameters were obtained according to these parameters. It was observed that Δ H , Δ S , and E a increased with increase in the length of the alkyl chain. The adsorption of the inhibitor on the steel surface is an exothermic, spontaneous, entropy process.

The influence of organic modification on the cytotoxicity of clay particles to keratinocytes, hepatocytes and macrophages; an investigation towards the safe use of polymer-clay nanocomposite packaging

Organically modified clays can be used as nanofillers in polymer-clay nanocomposites to create bio-based packaging with improved strength and barrier properties. The impact of organic modification on the physico-chemical properties and toxicity of clays has yet to be fully investigated but is essential to ensure their safe use. Two organoclays, named N116_HDTA and N116_TMSA, were prepared using a commercially available sodium bentonite clay and the organic modifiers hexadecyl trimethyl ammonium bromide (HDTA) and octadecyl trimethyl ammonium chloride (TMSA). An in vitro hazard assessment was performed using HaCaT skin cells, C3A liver cells, and J774.1 macrophage-like cells. Organic modification with HDTA and TMSA increased the hazard potential of the organoclays in all cell models, as evidenced by the higher levels of cytotoxicity measured. N116_TMSA caused the greatest loss in viability with IC50 values of 3.2, 3.6 and 6.1 μg/cm2 calculated using J774.1, HaCaT and C3A cell lines, respectively. Cytotoxic effects were dictated by the amount of free or displaced organic modifier present in the exposure suspensions. The parent bentonite clay also caused distinct cytotoxic effects in J774.1 macrophage-like cells with associated TNF-α release. Such information on the hazard profile of organoclays, can feed into risk assessments for these materials.

Effect of Layer Charge on Adsorption Properties of Octadecyl Trimethyl Ammonium Chloride by Montmorillonite

Effect of Layer Charge on Adsorption Properties of Octadecyl Trimethyl Ammonium Chloride by Montmorillonite

Preparation and surface activity study of amino acid surfactants

Quaternary ammonium cationic surfactants are widely applied in many different fields, such as textile, cosmetic, and petrochemical industries. However, little research has been done on the effects of anion on cationic surfactants. In this study, two new surfactants, cetyltrimethylammonium glycine (CTAG) and octadecyltrimethylammonium glycine (OTAG), were prepared in a simple way using cetyltrimethylammonium chloride (CTAC), octadecyltrimethylammonium chloride (OTAC), and glycine. Then the surface activities were evaluated and compared with the two raw materials. The surface activity of CTAG and OTAG, including surface tension, foaming ability, and emulsification, is better than that of CTAC and OTAC in each case. With the glycine, the corrosion inhibition efficiencies of CTAG and OTAG are 91.12% and 97.89%, respectively, which are more effective than that of CTAC and OTAC. The superior performance of the two surfactants will be very helpful for developing an effective solution in the future.

EFFECTS OF MAGHNITE NANOCLAY MODIFICATION AND COMPATIBILIZATION ON THE PHYSICAL AND MORPHOLOGICAL PROPERTIES OF POLY(VINYL CHLORIDE)/POLY(ETHYLENE-CO-VINYL ACETATE) BLENDS

In this research work poly(vinyl chloride)(PVC), ethylene vinyl acetate copolymer (EVA), and Maghnite nanoclay (MGT) were used to prepare PVC/EVA nanocomposites. The MGT clay was intercalated with octadecyltrimethylammonium chloride (ODTMA) and grafted with γ-aminopropyltriethoxysilane (APTES). The blend nanocomposites were prepared through the melt mixing of PVC/EVA blend at a weight ratio of 50/50 (wt%/wt%) with 20 wt% of compatibilizer; ethylene vinyl acetate grafted with an alcohol (EVA-g-OH) and 3 wt% of modified MGT clay using a Brabender plastograph. The nanocomposites so prepared were characterized using X-ray diffraction, TGA/DTA, mechanical tests and SEM. The results showed that when PVC was blended with EVA, with the modified MGT and with the compatibilizer, synergistic effects in the thermal stability and mechanical properties were observed.

Isothermal Crystallization Properties and Improved Rheological Performance of Waxy Crude Oil using Polyoctadecylacrylate-Modified Montmorillonite Composite as a Pour Point Depressant

AbstractRecently, studies on the use of polymer nanomaterial composites as pour-point depressants (PPD) have drawn much attention, but the crystallization properties and improved rheological performance of waxy crude oils using nanoclay-based composite PPDs have rarely been reported. In this paper, montmorillonite (Mnt) was first organically modified using octadecyltrimethylammonium chloride (C21H46NCl, or stearyltrimethylammonium chloride) in aqueous solution. Then, the organically modified Mnt (OMnt) material was dispersed into a polyoctadecylacrylate (POA) matrix to prepare a POA/OMnt composite PPD by melt blending. The composition, structure, and morphology of Mnt, OMnt, and the POA/OMnt composite PPDs were investigated. The results showed that the OMnt and POA were compatible and that the OMnt was exfoliated into several sheets in the POA matrix. Subsequently, the isothermal crystallization kinetics of the POA/OMnt composite PPDs showed that small amounts of OMnt had a dramatic impact on POA chain motion during crystallization and facilitated POA crystallization. After it was added to a waxy crude oil, the POA/OMnt composite PPDs produced better rheological properties and performance than identical concentrations of the neat POA. The POA/OMnt composite PPDs can act as wax nucleation sites for wax molecule precipitation and result in larger and more compact wax crystal flocs, which adversely affect the formation of a wax crystal network and, thus, favor the improvement of waxy crude oil rheology.

Adsorption of phenol from aqueous solution by four types of modified attapulgites

To study the adsorption of phenol by various modifications of attapulgite, four modifiers (hydrochloric acid, octadecyl trimethyl ammonium chloride, nitrilotriacetic acid and ethanediamine) were chosen and the phenol removal properties of the aqueous solution were explored. All modified attapulgite samples were characterized by SEM and FTIR, which revealed that the modified attapulgites had different surface structures and that the modifier groups successfully grafted onto the surface of the attapulgite. Effects of dosage, pH, the concentration of sodium ions and temperature on the adsorption capacity were evaluated. In this experiment, phenol removal was maximized at an adsorbent’s dosing concentration of 200 g L−1. The sorption kinetic data could be well represented by a pseudo-second-order model. The Langmuir equation agrees very well with the equilibrium isotherm. The findings herein suggest that octadecyl trimethyl ammonium chloride modified attapulgite may be a cost-effective and highly efficient material for phenol removal, with removal rates of more than 90% in aqueous solutions with low concentrations of sodium ions, at room temperature and a pH of 3. In conclusion, octadecyl trimethyl ammonium chloride modified attapulgite was superior to other forms of attapulgite as a phenol absorbent.

One‐pot synthesis of sheet‐like MFI as high‐performance catalyst for toluene disproportionation

AbstractIn this study, one‐pot hydrothermal synthesis of sheet‐like ZSM‐5 as a high‐performance catalyst for toluene disproportionation was carried out using binary surfactants. In the dual template, tetraethylammonium hydroxide was used to construct the microporous structure of ZSM‐5, and cationic surfactant (e.g., octadecyltrimethylammonium chloride (C18TMAC), hexadecyltrimethyl ammonium bromide (C16TMAB), and tetradecyltrimethylammonium bromide, (C14TMAB)) can change the growth habits of the ZSM‐5 crystals by hindering the regular stacking of zeolite layers from their longer hydrophobic chain. From the XRD pattern of the as‐synthesized samples which were hydrothermally treated for different time, it was found that a lamellar mesostructured intermediate gradually transformed into the sheet‐like ZSM‐5 during hydrothermal process. With a proper amount of cationic surfactant, the thickness of the sheet‐like ZSM‐5 could be controlled to less than 30 nm. Concerning the catalyst application, the toluene disproportionation performance over the sheet‐like ZSM‐5 is 1.5 times higher than that of the commercial ZSM‐5. The higher conversion is ascribed to the faster diffusion amount due to the sheet‐like ZSM‐5.

Investigation of cationic surfactants as clean flow improvers for crude oil and a mechanism study

Cetyl trimethyl ammonium chloride (CTAC), cetyl trimethyl ammonium bromide (CTAB), and octadecyl trimethylammonium chloride (OTAC) were evaluated as clean flow improvers for crude oil. The results showed that all of them have some effect on the viscosity of crude oil in a certain temperature range, and can depress the pour point, among which CTAC is the most potent one. The viscosity was reduced to below 540 mPa s under different concentration at 35 °C by CTAC, and it can depress the pour points by 7.5 °C with the concentration of 0.03%. DSC analysis and microscopic morphology analysis discovered the interaction of CTAC and saturated hydrocarbon component of the crude oil, which can reduce the wax peak temperature and wax precipitation point of crude oil. CTAC may precipitate and pack with the long-chain alkane to form the crystal nucleus, while the cationic part and the corresponding Cl− anion can act as a wax crystal modifier and block the wax crystal to grow up, thereby reduce the risk to form three-dimensional networks.

2D PdAg Alloy Nanodendrites for Enhanced Ethanol Electroxidation.

The development of highly active and stable electrocatalysts for ethanol electroxidation is of decisive importance to the successful commercialization of direct ethanol fuel cells. Despite great efforts invested over the past decade, their progress has been notably slower than expected. In this work, the facile solution synthesis of 2D PdAg alloy nanodendrites as a high-performance electrocatalyst is reported for ethanol electroxidation. The reaction is carried out via the coreduction of Pd and Ag precursors in aqueous solution with the presence of octadecyltrimethylammonium chloride as the structural directing agent. Final products feature small thickness (5-7 nm) and random in-plane branching with enlarged surface areas and abundant undercoordinated sites. They exhibit enhanced electrocatalytic activity (large specific current ≈2600 mA mgPd-1) and excellent operation stability (as revealed from both the cycling and chronoamperometric tests) for ethanol electroxidation. Control experiments show that the improvement comes from the combined electronic and structural effects.

Effect of modification extent of montmorillonite on the performance of starch nanocomposite films

The mechanism of the influence of organically modified montmorillonites (OMts) with different modification extents on starch/OMt nanocomposites was investigated. The nanostructures of OMts and their dispersion in starch films were analyzed using X‐ray diffraction (XRD) and transmission electron microscopy (TEM), respectively. The modifier content in the OMts increased with an increase in the added amount and molecular weight of the modifiers. The highest d‐spacing of 3.71 nm was achieved for the OMt modified with 30% dioctadecyl dimethyl ammonium chloride (DDAC). Intercalated nanostructures were formed between starch and the OMts modified with DDAC, whereas exfoliated nanostructures were formed between starch and the OMts modified with octadecyltrimethyl ammonium chloride (OAC) and octadecyl dimethyl benzyl ammonium chloride (ODBAC). The films with the OMt modified with 50% DDAC exhibited the highest tensile strength of 6.22 MPa. The water vapor permeability (WVP) of the film with the OMt modified with 30% DDAC exhibited a minimum value of 1.63 × 10−10 g · m/m2 · s · Pa. The amount and types of the modifiers in the OMts significantly influenced the structure and properties of the starch/clay nanocomposites. For a given polymer, the modification extent of Mt should be optimized to achieve high‐performance nanocomposites.

In vitro anti-microorganism activity and detergency of Sapindus mukorossi extract based on surfactive nature

Abstract This study aimed to improve the development and utilization of an aqueous extract of Sapindus saponins (SW) from the pericarp of Sapindus mukorossi Gaertn and fermentation product (SWF) by focusing on its surfactive nature. Compound systems containing SWF and fatty alcohol polyoxyethylene ether sodium sulphate, octadecyl trimethyl ammonium chloride, alkyl poly glycoside (APG), and fatty alcohol polyoxyethylene ether were produced, and their detergency and antimicrobial activity were determined. The surfactive nature of SWF was higher compared with that of SW, to different degrees, and its compound system with APG showed the best surfactive activity. The detergency ability of SWF/APG was also higher, to different degrees, compared with SWF and APG based on three types of representative soiled swatches and standard cleaning requirements at the level of 16.7/33.4 mg/mL (SWF/APG, weight per weight). Compared with SWF, the antimicrobial activity of SWF/APG was significantly better ( P Escherichia coli, Staphylococcus aureus, Pseudomonas aeruginosa, Trichophyton rubrum , and Candida albicans . Our results show that Sapindus saponins have the potential for functionality development as a natural detergency resource.

Novel family of periodic mesoporous organosilicas containing azobenzene within the pore walls

Three new bis-silylated azobenzenes, differently substituted, having terminal triethoxysilyl groups attached directly to the para position of the phenyl rings without linker, namely bis(4-triethoxysilyl)azobenzene, bis(2,6-dimethyl-4-triethoxysilyl)azobenzene and bis(2,6-diisopropyl-4-triethoxysilyl)azobenzene, have been successfully synthesized by Lithium-Iodine exchange from its diiodoazobenzene-derivatives, and used to prepare three novel azobenzene-bridged periodic mesoporous organosilica materials (Azb-PMO-R, R= H, Me and iPr). The synthesis of these materials from 100% of bis-silylated azobenzenes precursors was carried out under basic conditions using octadecyltrimethylammonium chloride (C18TMACl) as structure-directing agent. The successful synthesis was verified by N2 sorption measurements, solid state MAS-NMR spectroscopy, and IR spectroscopy. Materials with pore sizes between 3.7 and 4.6 nm and specific surface areas in the range of 400–700 m2/g were obtained. UV–Visible spectroscopy shows that the prepared PMOs are formed by rigid combination of isomers cis and trans of azobenzene moieties, which do not exhibit a regular photochemical trans-to-cis isomerization of the azo group upon alternating UV–Visible irradiation. However, these materials probably exhibit a dynamic and local bending which could be useful for reversible gas adsorption and release with light.

Rheological properties of organo-palygorskite in oil-based drilling fluids aged at different temperatures

Aiming to develop a new excellent rheological additive for use in oil-based drilling fluids, palygorskite (Pal) was organically modified with three cationic surfactants using wet method. The surfactants were octadecyl trimethyl ammonium chloride (C18-A), benzyl dimethyl octadecyl ammonium chloride (C18-B) and dimethyl dioctadecyl ammonium chloride (DC18). The structure and properties of organo-palygorskite (OPal) and its use in oil-based drilling fluids were characterized by X-ray diffraction (XRD), scanning electronic microscope (SEM), thermal analysis, gel volume and rheological tests. Surfactant-modification did not change the crystal structure of Pal, but changed the aggregation of Pal fibers. Surfactants mainly coated on the surface of Pal. But the details were influenced by the molecular scale of surfactants and the coating level. The scale of polar heads of surfactants being smaller than the channels' scale is expected. Surface modification decreased the particle size of Pal and loosened the arrangement of Pal fibers. The thermal stability of OPal decreased as follows: C18-A-Pal>C18-B-Pal>DC18-Pal, as well as the thermal stability of corresponding oil-based drilling fluids. Particularly, C18-A-Pal fluids could bear heat of 200°C. OPal could increase the viscosity of oil-based drilling fluids well. In addition, the oil-based drilling fluids containing OPal showed excellent thixotropy aged above 150°C. Temperatures below 150°C increased the rheological properties of oil-based drilling fluids while high temperature helped to disperse the OPal particles and fibers. The rheological properties of oil-based drilling fluids containing OPal were influenced by surfactants nature (polar head scale of surfactant cation, Hydrophilic-Lipophilic Balance (HLB) value, molecular conformation), coating level and temperature. The rheological properties of OPal fluids indicated that OPal was very suitable for oil-based drilling fluids.

Effect of STAC on Structure of Biotite when Biotite Transform to Hydrated Ba-Mica

After Ba2+/K+ ion exchange, hydrated Ba2+ replaced K+ from interlayer spacing of biotite. original biotite transformed to vermiculite-type hydrated Ba-mica. in order to study the effect of long-chain alkylammonium on biotite after structure changes, biotite, hydrated Ba-mica and mixing mica (A mixture of biotite and hydrated Ba-mica) were used to be modified by STAC (octadecyl trimethylammonium chloride). Fourier transform infrared spectroscopy and powder X-ray diffraction spectroscopywere were used to characterize the obtained samples to reveal the changes of interlayer spacing and basal spacing. The results showed that STA+ could not enter into the interlayer spacing of biotite but enter into that of hydrated Ba-mica and mixing mica. Almost all basal spacing of Ba-mica and mixing mica were increased to 2.8nm.

Synthesis and characterization of UV-curing epoxy acrylate coatings modified with organically modified rectorite

Epoxy acrylate (EA) coatings modified with organically modified rectorite (OREC) were synthesized employing the ultraviolet-curing technique. Two kinds of alkyl ammonium ions, octadecyltrimethylammonium chloride (OTAC) and [2-(methacryloyloxy)ethyl]trimethylammonium chloride (MAOTMA), were used to modify rectorite (REC). The methacrylate functionalities of MAOTMA were capable of reacting with the acrylate groups of EA. The structure of OREC was characterized by FTIR and XRD and the results indicated that the surfactants were successfully intercalated into the REC interlayers via cation exchange process. The morphology of nanocomposites was investigated by SEM and TEM. OREC showed better dispersion in EA matrix compared with unmodified REC. The T g of neat EA obtained by DMA was 75.6°C, while for 5 wt% EA/MAOTMA-REC and EA/OTAC-REC nanocomposites it increased to 76.5 and 80.8°C, respectively. The nanocomposite with 3 wt% loading of OTAC-REC had the highest T g (89.7°C). TGA revealed that the thermal stability of nanocomposites was enhanced by OTAC-REC and MAOTMA-REC and the thermal stability of EA/MAOTMA-REC nanocomposites was better than that of EA/OTAC-REC nanocomposites. The mechanical properties of nanocomposites containing OTAC-REC and MAOTMA-REC were better than those of nanocomposites containing unmodified REC. With increasing OREC content, the adhesive force of nanocomposites decreased slightly and the flexibility increased significantly.

Restraining Na-Montmorillonite Delamination in Water by Adsorption of Sodium Dodecyl Sulfate or Octadecyl Trimethyl Ammonium Chloride on the Edges

The delamination of montmorillonite in water leads to sliming in ore slurry, which is detrimental to mineral flotation and solid/water separation. In this work, the delamination of Na-montmorillonite (Na-MMT) has been restrained by sodium dodecyl sulfate (SDS) or octadecyl trimethyl ammonium chloride (1831) through the adsorption on the edge of the mineral. The experimental results have shown that the pretreatment by adding SDS and 1831 could greatly reduce the Stokes size percentage of −1.1 µm particles in the aqueous Na-MMT suspension. From the X-ray diffractometer (XRD) results, the interlayer spacing of the MMT pre-treated by SDS and 1831 is smaller than that of original MMT particles. Adsorption position of SDS and 1831 on MMT surfaces was analyzed by the measurements of adsorption capacity of SDS and 1831, inductively-coupled plasma spectra, and zeta potential before and after the plane surface of MMT was covered with tetraethylenepentaminecopper ([Cu(tetren)]2+). The results indicated that SDS and 1831 are adsorbed on the edge and the whole surface of Na-MMT, respectively. Delamination of MMT could be well restrained by the adsorption of SDS and 1831 on the edges of MMT.

Mass scale calibration of TOF‐SIMS spectra with molecular ions of internal additives

The applicability of internal additives for mass scale calibration in time‐of‐flight secondary ion mass spectrometry (TOF‐SIMS) was studied. Relation between the ions selected for mass scale calibration and the relative mass accuracy of the target molecular ions was investigated. Didecyldimethylammonium bromide (dC10DMA+Br−), dioctadecyldimethylammonium chloride (dC18DMA+Cl−) and tetradecyltrimethylammonium chloride (C14TMA+Cl−) as target molecules and octadecyltrimethylammonium chloride (C18TMA+Cl−) as an internal additive were prepared for positive TOF‐SIMS spectra. Tinuvin 770 as a target molecule and sodium hexadecyl sulfate (C16OSO3−Na+) as an internal additive were used to evaluate negative TOF‐SIMS spectra. In the case of dC10DMA+Br−, dC18DMA+Cl− and Tinuvin 770, the relative mass accuracy of the target molecular ions tends to be improved by mass scale calibration using the molecular ion of the internal additive. The relative mass accuracy of the molecular ion of the target ensured by the mass scale calibration using internal additives was less than approximately ±46 ppm. In some cases, however, internal additives highly effect on samples and change the sample properties because of coverage of the sample, removing a target molecule or causing matrix effects. It is necessary to evaluate the influence of the internal additive addition before applying internal additives. The detection of target ion peak should be especially confirmed after the addition of the internal additive. When samples are not influenced by internal additive addition, the internal additive method is effective for accurate mass calibration. Copyright © 2016 John Wiley & Sons, Ltd.

Effect of intercalating agents on structure and properties of dimer acid‐based polyamide modified by in situ doping of Na‐montmorillonite

Under the condition of 0.4% (mass), the effects of intercalating agents on conglomeration structure and thermal and mechanical properties of dimer acid‐based polyamide (DAPA) were investigated. The results show that layer‐stripped Na‐montmorillonite (MMT) with octadecyl trimethyl ammonium chloride caused a sharp decrease of content of the γ crystal phase in DAPA, thus bringing out decrease in mechanical properties and increase in IZOD notched impact strength while a sharp increase of content with the γ crystal phase in DAPA modified by Na‐MMT with dioctadecyl dimethyl ammonium chloride. Thus, it brought out a large increase in mechanical properties and a limited increase in IZOD notched impact strength. The decomposition reaction processes of DAPA modified by Na‐MMT and Na‐MMT with octadecyl trimethyl ammonium chloride were one step ranging from 410 to 500°C, respectively. The thermal decomposition reaction processes of DAPA modified by Na‐MMT with dioctadecyl dimethyl ammonium chloride were two steps. Copyright © 2016 John Wiley & Sons, Ltd.