Stearyltrimethylammonium Bromide Research Articles

Amino-Functionalized Pore-Expanded MCM-41 for CO2 Adsorption: Effect of Alkyl Chain Length of the Template

Solid adsorbents modified with N-containing functional groups have been extensively studied due to their excellent CO2 adsorption performance. In this work, an adsorbent was obtained to capture CO2 by impregnating polyethylenimine (PEI) into MCM-41 with a reserved template that had different alkyl chain lengths [myristyltrimethylammonium bromide (C14), cetyltrimethylammonium bromide (C16), and stearyltrimethylammonium bromide (C18)]. The thermogravimetric analysis, small-angle X-ray diffraction, N2 adsorption–desorption, Fourier transform infrared (FTIR) spectroscopy analysis, and in situ FTIR spectra were employed to study the properties of adsorbents. The results showed that the template had been successfully introduced into the supports in the synthetic process, and the CO2 adsorption performance was quite sensitive to the alkyl chain length of the template. Besides, the adsorbent with the template (C16) exhibited the highest CO2 adsorption capacity (2.49 mmol/g) and amine utilization rate (0.28 mmol CO2/mmol N) under 25 °C and pure CO2. It is believed that the appropriate alkyl chain length of the template could act as an important role in the enhancement of PEI distribution and decrease the CO2 transfer resistance, thereby improving the CO2 adsorption capacity.

Tuning redox ability of Zn3In2S6 with surfactant modification for highly efficient and selective photocatalytic C-C coupling

Heterogeneous photocatalytic C-C coupling is a green and efficient approach to producing valuable chemicals. The strategies for guiding effective photocatalyst design are desired but still limited. Here, we report visible-light-driven highly selective photocatalytic C-C coupling of benzyl alcohol over surfactant-modified Zn3In2S6 semiconductors. A complete switch of product selectivity from benzyl aldehyde (91.5 %) to C-C coupling products (96.5 %) is obtained by the modification of Zn3In2S6 with stearyl trimethyl ammonium bromide (STAB). This modification assists the formation of sulfur vacancies on Zn3In2S6 to enhance charge carrier separation, thereby increasing the photocatalytic activity. The selectivity switch is mainly attributed to increasing conduction band position of Zn3In2S6 by surfactant modification which strengthens the reduction ability of photogenerated electrons to induce the reversible reduction of benzyl aldehyde to ketyl radicals, and partially to the poor oxidation ability of the material that inhibits the oxidation of ketyl radicals to benzyl aldehyde. Encouragingly, this universal protocol has been successfully applied to a series of aromatic alcohols and biomass-derived furanic alcohols to selectively produce C-C coupling products.

Headgroup interaction effects in mixed fatty acid-alkyl amine monolayers

The impact of headgroup interactions in binary mixed monolayers comprised of fatty acids and alkyl amine-based surfactants has been investigated with a view towards understanding molecular pair formation at the air-water interface. Monolayers consisting of equimolar mixtures of cationic Stearyltrimethylammonium bromide with myristic acid (STAB/MA), and nominally neutral octadecyl amine with myristic acid (ODA/MA) were studied using a combination of Langmuir monolayer methods. Measurements support the formation of molecular pairs between STAB and MA in monolayers, which was not observed for the ODA/MA mixture. By studying the effect of subphase pH, measurements suggest hydrogen bonding between the headgroups and surrounding water significantly impacts film structure for the mixed systems. Notably, at pH 3.5, similarities in film morphology for the STAB/MA and the ODA/MA were observed, indicating that subphase pH can be used to enhance pair formation. This lower pH promoted the formation of phase-separated domains with LE and LC features and changed the kinetic stability of the monolayers. These works clarify the fundamental importance of headgroup interactions, hydrogen-bond formation and chemical structures in regulating intermolecular pair formation, an issue that has been largely unreported and underappreciated in the literature to date. This information can provide guidance on important intermolecular interaction considerations that must be taken into account for applied systems.

Sensitive analytical detection of nitrite using an electrochemical sensor with STAB-functionalized Nb2C@MWCNTs for signal amplification

An electrochemical sensor based on stearyl trimethyl ammonium bromide - functionalized niobium carbide@multi-walled carbon nanotubes (Nb2C@MWCNTs-STAB) for signal amplification was successfully constructed for sensitive detection of nitrite (NO2−). Niobium carbide@multi-walled carbon nanotubes (Nb2C@MWCNTs) with high electrical conductivity and water dispersibility were first prepared in a one-pot hydrothermal synthesis, after which cationic STAB was added to overcome the negative surface charge on the Nb2C@MWCNTs. The electrostatic attraction between Nb2C@MWCNTs-STAB and NO2− was improved by the STAB, which enhanced the sensitivity of the constructed sensor for NO2−. Under optimized conditions, Nb2C@MWCNTs-STAB/GCE exhibited excellent analytical performance for detection NO2− with two wide liner ranges (0.1–100 μmol L−1 and 100–2000 μmol L−1) and a limit of detection of 0.022 μmol L−1. Nitrite recovery tests in milk and spinach samples showed recoveries in the range of 89.82–104.52%. The NO2− residues in ham and pickled vegetable (cedrela sinensis) samples were analysed using the presented sensor and a spectrophotometric method, with no significant difference found between the results of the two methods.

Molecular interaction for quasi-binary mixture of N-acyl amino sulfonate amphoteric surfactant from castor oil and stearyltrimethyl ammonium bromide

The micellization behavior and the molecular interaction of quasi-binary mixture constituted by an amphoteric sodium N-acyl amino sulfonate based on castor oil (AAS-CO) with a cationic stearyltrimethyl ammonium bromide (STAB) in aqueous solution at 298.15 K were investigated using both the tensiometry and the conductometry and the two techniques were adopted to determine the mixed critical micelle concentration (cmc). Based on the regular solution theory and in the framework of the pseudophase separation model, Rubingh’s model and Clint’s model were adopted to estimate the mole fractions and the activity coefficients in mixed micelle, the interaction parameters between quasi-one AAS-CO and STAB. Also, thermodynamic parameters were obtained by thermodynamic models. Synergistic interaction between surfactants and non-ideal mixing were observed in the entire range of composition in this investigation. The addition of quasi-one AAS-CO into aqueous solution can induce the alteration of interaction behavior between surfactants, which can be explained rationally by the shielding effect, the electrostatic repulsion and the steric hindrance. Thermodynamic parameters imply that it appears an enthalpically spontaneous behavior in the process of micellization and there exists a largest negative deviation of free energy change of micellization from the ideal case at the optimum composition in which a maximum synergism happens. These findings will help with understanding the molecular interaction between quasi-one component and other one in surfactant mixtures.

Electrochemical detection of methotrexate in serum sample based on the modified acetylene black sensor

A novel acetylene black (AB) sensor modified with stearyltrimethylammoniumbromide (STAB) was fabricated and applied to the determination of methotrexate (MTX) in serum. For the strong adsorption of STAB and the high catalytic capacity of AB, the prepared sensor performed better adsorption and electrochemical catalysis capacity compared with acetylene black paste electrode (ABPE). Several factors affecting the performance of the sensor, such as the construction of the sensor and the parameters affect the electrochemical catalysis were optimized carefully on sequences in this study. The prepared sensor showed favorable performance in the determination of MTX with the linear range of 0.005 μM to 7.0 μM and the detection limit of 3.07 nM. Furthermore, the fabricated sensor exhibited good stability and repeatability, which was of importance in the electrochemical detection. Finally, the established electrode was employed in the detection of MTX in real sample of serum, which demonstrated the reliable and accurate of the prepared method. It is obvious that the prepared sensor existed great potential in the determination of MTX, which could provide a new approach for the fast and low-coat detection for MTX.

Effect of Emulsifier on the Structure and Properties of Waterborne Silicone Antifouling Coating

Three-component waterborne silicone antifouling coatings, which could cured at room temperature, were prepared, respectively, with cationic (stearyl trimethyl ammonium bromide) or anionic (sodium dodecyl benzene sulfonate) silicone emulsion as a film-forming substance, γ-methacryloxypropyltrimethoxysilane as a curing agent and dibutyltin dilaurate as a catalyst. The effect of emulsifier on the structure and properties of silicone coating was studied. The results showed that the coating with cationic silicone emulsion had high crosslinking density, and its surface is smooth. The surface of the coating prepared by the anionic silicone emulsion is rough. Emulsifier type had no obvious effect on the surface free energy of the waterborne silicone coating. The coatings have the characteristics of low surface energy and excellent bacterial desorption properties. Stearyl trimethyl ammonium bromide in the cured coating can reduce the adhesion of marine bacteria on the coating surface. Both the emulsifiers can inhibit the activity of Navicula Tenera. The waterborne silicone coating prepared by cationic silicone emulsion has better comprehensive mechanical properties and antifouling performance.

Study of STAB- and DDAB-modified sepiolite tructures and their adsorption performance for emulsified oil in produced water

Electrostatic adsorption and hydrophobicity constitute the main functions of effective removal of emulsified oils (EOs) in produced water. Here, sepiolite (Sep) is modified with single-chain and double-chain organic cation surfactants, stearyl trimethyl ammonium bromide (STAB) and dimethyl dioctadecyl ammonium bromide (DDAB). Analyses of SEM, CA and ζ-potential indicated that individually-dispersed Sep fibers modified to form Sep fibrous aggregates with a more hydrophobic and electropositive surface, which greatly improved EOs adsorption and oil-water separation efficiency, and EOs removal efficiency exceeded 99%. The maximum adsorption capacities were 957.0 mg/g for STAB-Sep and 1031.5 mg/g for DDAB-Sep, suggesting that modified Sep with double chains exhibited a high affinity for EOs. Both the Langmuir and the Freundlich isotherms could be used to explain the adsorption process. Thermodynamic parameters proved that the adsorption process was a spontaneous endothermic physical process. This study provides a theoretical foundation for the design of high-efficiency and low-cost organoclay adsorbents.

Design and functionalization of magnetic ionic liquids surfactants (MILSs) containing alkyltrimethylammonium fragment

A series of magnetic ionic liquids surfactants (MILSs) containing alkyltrimethylammonium fragment {dodecyltrimethylammonium bromotrichloroferrate (III) ([DTA][FeCl3Br]), tetradecyltrimethylammonium bromotrichloroferrate (III) ([TTA][FeCl3Br]), cethyltrimethylammonium bromotrichloroferrate (III) ([CTA][FeCl3Br]), and stearyltrimethylammonium bromotrichloroferrate (III) ([STA][FeCl3Br])} were synthesized and characterized by FT-IR, Raman and MS (ESI) spectra. The physical properties including thermal stability, density and magnetic susceptibility were determined, which revealed that the MILSs had good thermal stability (Td > 210 °C) and considerable magnetic susceptibility (xg > 3.2 × 10−5 emu·g−1). The critical micelle concentration (CMC) values of MILSs aqueous solutions based both on electrical conductivity method and surface tensiometry demonstrated that MILSs had better surface active than the corresponding nonmagnetic parent surfactants {dodecyltrimethylammonium bromide (DTAB), tetradecyltrimethylammonium bromide (TTAB), cethyltrimethylammonium bromide (CTAB) and stearyltrimethylammonium bromide (STAB)}. Moreover, the surface tensiometry in a magnetic field revealed that the MILSs showed a magnetically induced reduction in surface tension. With surface active and magneto-responsivity bi-functional properties, allow these MILSs pretend to be manipulated noninvasively and reversibly by an applied external magnetic field in further potential applications such as colloid and surface chemistry.

Deep Oxidative Desulfurization of Model fuels by Prepared Nano TiO2 with Phosphotungstic acid

In this study, nano TiO2 was prepared with titanium isopropoxide (TTIP) as a resource to titanium oxide. The catalyst was synthesized using phosphotungstic acid (PTA) and, stearyl trimethyl ammonium bromide (STAB) was used as the structure-directing material. Characterization of the product was done by the X-ray diffraction (XRD), X-ray fluorescent spectroscopy (XRF), nitrogen adsorption/desorption measurements, Atomic Force Microscope (AFM) and Fourier transform infrared (FTIR) spectra, were used to characterize the calcined TiO2 nanoparticles by STAB and PWA. The TiO2 nanomaterials were prepared in three crystalline forms (amorphous, anatase, anatase-rutile). The results showed that the nanoparticles of anatase TiO2 have good catalytic oxidative activity. This is because of the conversions of 100% within 90 sec from 300 ppm of dibenzothiophene. This is compared to conversion rates for anatase–rutile nanoparticles and amorphous nanoparticles which reached 52% and 31 %, respectively. The influence of the temperature of reaction, catalyst amount, H2O2 concentration, and initial DBT concentration on the oxidation of DBT was investigated.

Electrodeposition and Properties of Composites Consisting of Carbon Nanotubes and Copper

Copper–matrix–carbon nanotubes (Cu–CNTs) composite films were prepared in a Cu plating solution with multiwall carbon nanotubes (MWCNTs) using electrodeposition. The MWCNTs surface treatment method, electroplating solution system, electroplating conditions, heat treatment process and other parameters of this process are discussed. The results showed that MWCNTs purified by HCl treatment and dispersed by stearyltrimethylammonium bromide are more suitable as add-on materials for the preparation of the copper matrix composite films by electrodeposition. An appropriate heat treatment process was able to improve the structures and properties of the composite films. The final products showed that the MWCNTs were evenly distributed in the composite films and joined with the copper grains to form a mutually entangled mesh structure with excellent corrosion resistance (3.19 × 10−8 Ω M) and a hardness of 53.5 HV. All this was possible through extensive optimization of the electrodeposition and post-treatment parameters.

Creviced titanate nanotube modified with stearyl trimethyl ammonium bromide as a support for amine-based CO2 sorbent

In this paper, a series of protonated titanate nanotubes (PTNTs) modified by stearyl trimethyl ammonium bromide (STAB) were prepared as supports for Polyethyleneimine (PEI)-based sorbents. The CO2 adsorption performance was evaluated in a self-assembled fixed bed reactor. The typical sorbents were characterized by XRD, EDS, SEM, HR-TEM, N2 adsorption-desorption, FT-IR and TGA. Results indicate that the modification significantly improves CO2 adsorption capacity of the sorbents. The maximum CO2 adsorption amount of 2.22 mmol/g was obtained over the modified PEI-based sorbent in 2% CO2/air. Based on the characteristic analysis, the formation of creviced nanotubes, instead of intact nanotubes, is testified because of the modification. Such unique nanotubes possess the higher BET surface area and larger pore volume, which enables more PEI to uniformly distribute on the surface of modified PTNT supports. Especially, it is easier for PEI to enter the inner pores through the crevice than from tube orifices, avoiding pore blockage and facilitating CO2 diffusion in pores. The abundant amine-sites and small internal diffusion resistance endow the modified sorbent with large CO2 adsorption capacity. In addition, the PEI/PTNT adsorbent displays good thermal stability and reusability.

Control of pore size in shell of hollow silica–alumina composite spheres for hydrolytic dehydrogenation of ammonia borane

In the present study, we attempted to control the shell pore size of hollow spheres and investigated the resulting effect on their acidic properties and activity for the acid-promoted hydrolytic dehydrogenation of ammonia borane. Silica shells were formed on polystyrene template particles via sol–gel method, followed by calcination. For controlling the pore structure, surfactants with various molecular lengths (decyltrimethylammonium bromide (DeTAB), cethyltrimethylammonium bromide (CTAB), and stearyltrimethylammonium bromide (STAB)) were used. The shells of all the hollow spheres included monodispersed and well-ordered pores, and the pore size increased with increase in the molecular length of the surfactant. In particular, the hollow spheres prepared with CTAB and STAB consisted of numerous well-ordered mesopores with sharp peaks centered at approximately 2.4 and 2.8 nm, respectively. The molar ratios of the hydrolytically evolved hydrogen to the initial NH3BH3 in the presence of the hollow spheres prepared with DeTAB, CTAB, and STAB were 0.9, 3.0, and 2.7, respectively, which indicated the stoichiometric amount of hydrogen was evolved in the presence of the hollow spheres prepared with CTAB and STAB. The amount and rate of hydrogen evolution depended on the pore structure, and the hollow spheres with well-ordered and appropriate-sized mesopores in the shells showed a large amount and high rate of hydrogen evolution.

Surfactant-assisted preparation of nanohybrid for simultaneously improving enzyme-immobilization and electron-transfer in biosensor and biofuel cell

As enzyme-immobilization and electron-transfer are the key factors for fabricating an enzymatic bioelectrode and its devices, we investigated a strategy to simultaneously improve the two aspects by assistance of the cationic surfactant, stearyltrimethylammonium bromide (STAB). By electrodeposition method, we obtained a multifunctional STAB-modified nanomaterial on electrode surface to improve enzyme-immobilization and electron-transfer. On the one hand, STAB could firmly adsorb a substantial number of enzymes via electrostatic interaction in a favorable orientation on the conductive nanomaterial surface for electron-transfer. On the other hand, STAB acts as a dispersant and stabilizer for traditionally conductive nanomaterials (reduced graphene oxide, carbon nanotubes, and gold nanoparticles) to guarantee their unique properties and form a well-conductive network. Electrochemical measurements demonstrated that enzymatic electrodes based on the nanohybrid possessed fast electron-transfer rate, a large quantity of immobilized enzymes, and good activity toward glucose oxidation or oxygen reduction. The glucose biosensor performed linear response range of 0.01–11.71 mM, detection limit of 3.84 × 10−3 mM, and sensitivity of 10.42 μA mM−1 cm−2, while the glucose/O2 biofuel cell exhibited maximum power density of 121.87 μW cm−2 and open-circuit voltage of 0.663 V. Both of the devices showed better performances than those of devices without STAB or conductive nanomaterials in this work.

Organic Modification and Ball Milling of Bentonite and its Retention Properties

Stearyltrimethyl ammonium bromide(STAB) was used for organic modification of bentonite and then ball milled the modified bentonite. The organically modified bentonite was analyzed by FT-IR and XRD. The results show that the stearyltrimethyl ammonium bromide has been interalated into the layers of bentonite. The layer distance of the bentonite is increased from 1.256nm to 2.694nm. The appropriate experimental conditions of interplanar spacing increasing were the dosage of STAB 40%, reaction time 4h, temperature 75°C. The ball milled organically modified bentonite was analyzed by SEM. The results show that the particle mainly reach submicron to nanometer when ball mill 2h. The particle size distribution range is from 100nm to 500nm. Ball milled organically modified bentonite/ cationic guar gum(CGG) can improve retention rate of paper-process reconstituted tobacco pulp obviously than organically modified bentonite/CGG because of smaller grains and better unigormity of ball milled bentonite.

Formation of Ethylene–Silica Nanofibers with Concentric Circular Mesopores Inside and Lamellar Mesopores on the Surfaces

Ethylene-silica nanofibers with concentric circular mesopores inside and lamellar mesopores outside were prepared using stearyltrimethylammonium bromide (STAB) as template and (S)-beta-citronellol as a co-structure-directing agent. They were formed at the (S)-beta-citronellol/STAB molar ratio range of 3:1 to 4:1. Field emission scanning electron microscopy and transmission electron microscopy images taken after different reaction times revealed a phase transition from hexagonal to lamellar phase on the surface of the organic-inorganic hybrid silica nanofibers. The nanofibers with concentric circular pore channels were proposed to be formed from spherical micelles. With increasing the (S)-beta-citronellol/STAB molar ratio from 0.5:1 to 5:1, the morphology changed from short hexagonal rod to long nanofiber, and then to shrunk multilamellar vesicle. Moreover, 1,4-phenylene-silica nanofibers and nanoparticles with concentric circular mesopores inside and lamellar mesopores outside were also prepared.

Fabrication of carboxylic functionalized superparamagnetic mesoporous silica microspheres and their application for removal basic dye pollutants from water

Superparamagnetic mesoporous silica microspheres embedded with a silica-coated superparamagnetic iron oxide nanoparticles core and mesoporous silica shell have been prepared using stearyltrimethyl ammonium bromide (STAB) as surfactant template. The superparamagnetic mesoporous silica microspheres then were modified with anhydride functionalized silane to graft carboxylic groups and developed for removing basic dye pollutants, e.g., Methylene Blue (MB) and Acridine Orange (AO) from wastewaters. The results show that the as-prepared adsorbent exhibits high adsorption capacity, extremely rapid adsorption rate and separation convenience for basic dye pollutants removal. Furthermore, the as-prepared adsorbent can be regenerated by simple washing with acid solution to recover both the adsorbents and the adsorbed dyes. The regenerated adsorbent can be reused for dye removal and the adsorption efficiency is still above 88% even after use for seven times. So it can be used as an economic recyclable tool for dyes pollutants removal from wastewater.

Adsorption properties of Congo Red from aqueous solution onto surfactant-modified montmorillonite

A series of surfactant-modified montmorillonites (MMT) were prepared using octyltrimethylammonium bromide (OTAB), dodecyltrimethylammonium bromide (DTAB), cetyltrimethylammonium bromide (CTAB) and stearyltrimethylammonium bromide (STAB), and the organification of MMT was proved by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD), scanning electron micrographic (SEM) and transmission electron microscope (TEM). The adsorption of Congo Red (CR) anionic dye from aqueous solution onto surfactant-modified MMT was carried out. Compared with MMT, the adsorption capacity of surfactant-modified MMT for CR was greatly enhanced and MMT modified with CTAB (2.0 CEC) exhibited the higher adsorption capacity. The effects of pH value of the dye solution, adsorption temperature, adsorption time and the initial dye concentration on the adsorption capacity of CR on CTAB-MMT have been investigated. The results showed that the adsorption kinetic of CR on CTAB-MMT could be best described by the pseudo-second-order model and that the adsorption isotherm of CR was in good agreement with the Langmuir equation. The IR spectra and SEM analysis also revealed that the adsorption of CTAB-MMT was a chemical adsorption process between CTAB and the NH 2, –N N– and SO 3 groups of CR.

Synthesis of highly-ordered mesoporous silica particles using mixed cationic and anionic surfactants as templates

We applied a molecular assembly formed in an aqueous surfactant mixture of cationic cetyltrimethylammonium bromide (CTAB) and anionic sodium octylsulfate (SOS) as templates of mesoporous silica materials. The hexagonal pore size can be controlled between 3.22 and 3.66 nm with the mixed surfactant system. In addition, we could observe the lamellar structure of the mixed surfactants with precursor molecules, which strongly shows the possibility of precise control of both the pore size and the structure of pores by changing the mixing ratio of surfactants. Moreover, use of the cationic surfactant having longer hydrophobic chain like stearyltrimethylammonium bromide (STAB) caused the increase in d 100 space and shifted the point of phase transition from hexagonal phase to lamellar phase to lower concentration of SOS.

Catalysis by stearyltrimethylammonium bromide of the reaction between long chain alkanethiols and p-nitrophenyl acetate

The effect of stearyltrimethylammonium bromide (stab) upon the reaction between alkanethiols and p-nitrophenyl acetate has been examined in aqueous solution; below the critical micellar concentration (c.m.c.) of stab, the activities of thiols decrease with increasing carbon chain length, whereas, above the c.m.c., dodecanethiol is some 104 fold more reactive than in the absence of stab at pH 9.