Study of the influence factors on the synthesis of Fe-MCM-48 with binary mixed cationic and anionic surfactants

Highly ordered Fe-MCM-48 was synthesized by a mixed template method under low molar ratio (0.17:1) of mixed surfactants to silica. The effect of various factors, such as Fe sources, the amount of Fe salt, Si sources, surfactant/SiO₂, crystallization temperature and crystallization time on the synthesis were discussed in detail. The Debye-Huckel theory, the theory of salts formation, the local effective surfactant packing parameter theory and the charge balance theory were used to explain the reason that various factors can affect the product structure reasonably. The optimum synthesis conditions for Fe-MCM-48 were obtained.     

Influence of anionic and non-ionic surfactants on the synthesis of core-shell Fe3O4@TiO2 nanocomposite synthesized by hydrothermal method

Magnetite spinel nanoparticles (Fe₃O₄) coated titanium dioxide has been prepared by the solvo-hydrothermal method for application in dye degradation and wastewater remediation. The core-shell Fe3O4@TiO2 nanoparticles have been synthesized using titanium butoxide (TBT) and ferric chloride as precursors. In this method, firstly, magnetite nanoparticles have been prepared through a solvothermal process using ethylene glycol as a solvent. Then, titanium butoxide was used as a precursor to synthesize Fe₃O₄@TiO₂ core-shell nanoparticles using the hydrothermal method. The surfactants that were added, in separate synthetic processes, were anionic oleic acid and Sodium Dodecyl sulfonate, and non-ionic Polyvinylpyrrolidone and Polyethylene glycol. The effects of the various surfactants on the fabrication of core-shell magnetic nanoparticles were studied. Various characterization methods have been established to examine the morphology and magnetization features of the nanostructured particles, such as XRD, FTIR, TEM, FESEM, UV-spectroscopy, and VSM, etc., which validated the formation of Titania coated magnetite nanoparticles. The TiO₂ shell formation drastically reduces the saturation magnetization of the magnetic nanoparticles. The Oleic acid as a surfactant produces the smallest nanoparticles. The PVP coating is best amongst these surfactants for the retention of saturation magnetization upon coating.     

Synthesis,surface active and thermal properties of novel imidazolium cationic monomeric surfactants

A series of long chain water soluble cationics have been synthesized by using renewable raw materials like fatty alcohols and epichlorohydrin. The surface activity of the molecules has been determined by measurement of their conductance and surface tension in aqueous solution. The dynamics of surface activity of these surfactants have also been investigated in the presence of sodium halides, NaCl and NaBr by surface tension measurement. A series of useful parameters like critical micelle concentration (cmc), surface tension at the cmc (γ_cmc), adsorption efficiency (pC20), effectiveness of surface tension reduction (Π_cmc), Gibbs free energy of the micellization (ΔG_0 mic) and Gibbs free energy of adsorption (ΔG_0 ads) have been determined from the measurements obtained by surface tension and conductivity method. Further with the application of the Gibbs adsorption isotherm, maximum surface excess concentration (θ_max) and minimum surface area/molecule (A_min) at the air–water interface were also estimated. Thermal stability of these long chain cationics has been measured by thermal gravimetric analysis under nitrogen atmosphere. Analysis of thermal stability measurement indicated that the thermal stability of these long chain imidazoliums increase with an increase in chain length.     

氧化铝、改性氧化铝及硅酸铝的酸性特征(续)

介绍了氧化铝的酸性,其中包括酸度、酸强度、酸类型及酸位微观结构,在氧化铝中加入P、B、F、Ti、Zr或Si对酸性的影响,以及Y型沸石及其改性的酸性。     

有序介孔氧化铝的合成及稳定性研究

以硝酸铝为原料,聚乙二醇1540为模板剂,碳酸铵为沉淀剂,合成了有序介孔氧化铝。通过BET法比表面积测定以及透射电镜（TEM）、X射线衍射（XRD）分析,对合成的有序介孔氧化铝的结构特征进行了表征。重点考察了合成的有序介孔氧化铝在高温条件下的热稳定性。结果表明,合成的有序介孔氧化铝在高温条件下保持了良好的介孔结构,但比表面积有所降低。     

Head group-modified sophorolipids: Synthesis of new cationic, zwitterionic, and anionic surfactants

Amino acid-glycolipid conjugates were prepared using carbodiimide-mediated coupling methods. The amino acid units were multifunctional and possessed a para-aminobenzoic acid linker. The glycolipid used was a stearic sophoroside. The aim of preparing these modified sophorolipids was to increase their water solubility as well as to introduce sites at the polar head groups that permitted further chemical derivatization. After acidolytic or hydrogenolytic deprotection of the amino acid N-terminus or side chain, water-soluble compounds were obtained that displayed good surfactant properties. Critical micelle concentration values were clustered in the range of high 10⁻⁶ to low 10⁻⁵ M, and minimum surface tension values were below 40 mN m⁻¹. Two of the compounds represented more complicated structural classes, namely, gemini and bolaform surfactants.     

Comparison of the thermally stable conducting polymers PEDOT, PANi, and PPy using sulfonated poly(imide) templates

We showed that it is possible to use sulfonated poly(amic acid)s (SPAA) to template polymerize 3,4-ethylenedioxythiophene (EDOT) to PEDOT, resulting in an aqueous dispersion of conducting polymer. This study compares PEDOT with poly(aniline) (PANi) and poly(pyrrole) PPy using the same and another, more rigid, poly(amic acid) template. A variety of system parameters, including reaction time, conductivity, and overall thermal stability, were noted to change systematically depending on the systems chosen. PANi-SPAA takes less than one tenth of the reaction time of PEDOT-SPAA (12 h versus 7 days), and results in higher conductivities at room temperature (ca. 10 S/cm). However, it is not as thermally stable as the PEDOT-SPAA system; conductivity is not measureable after annealing at 300 °C. PPy-SPAA was found to be more thermally stable than PANi-SPAA (less mass lost at 300 °C), but it was still more conductive than un-doped PEDOT-SPAA by a factor of 1000 (ca. 1.0 S/cm).     

Comparison of the effects of anionic and cationic surfactant concentration on mean drop size in a mixer-settler extractor

In this study, the effect of Aniline and SDS (Sodium Dodecyl Sulfate) surfactant on mean drop size, D₃₂, was investigated in a horizontal mixer-settler. For this purpose, three series of experiments were conducted in a single stage mixer-settler on the liquid–liquid dispersion of a toluene–water system. At first, the effects of impeller speed and hold-up on the mean drop size were examined without any surfactant. Afterwards the same investigation was performed in the presence of SDS (Seri 1) and then in the presence of Aniline (Seri 2). The results revealed that D₃₂ in Aniline system is larger than D₃₂ in SDS system. In addition, the results show that D₃₂ in the presence of Aniline depends on the impeller speed with a power low function, having an exponent of −1.11 which has a good agreement with Hinze–Kolmogorov's theory.     

An excellent support of Pd catalyst for methane combustion: Thermal-stable Si-doped alumina

Thermal-stable Si-doped alumina was prepared by the reverse microemulsion method and was used as the support of Pd catalyst for the methane combustion. The physicochemical properties of Si-alumina and catalytic performance of Pd/Si-Al₂O₃ were characterized by XRD, N₂ adsorption, FT-IR, XPS and methane catalytic combustion. The results indicate that the presence of Si can increase the thermal stability of alumina and promote the coordination state of aluminum from tetrahedral to octahedral, but its content added should be controlled appropriately to 5–6 wt%. Si-doped alumina prepared by the reverse microemulsion method is an excellent support of Pd catalyst for the methane combustion, which can increase both the catalytic activity and thermal stability of the Pd catalyst. The studies also show that the calcination temperature of support affects remarkably the performance of catalyst, and the high thermal stability of support is very important to increase the performance of Pd catalyst for the methane combustion.     

Porous polymeric membranes by bicontinuous microemulsion polymerization: effect of anionic and cationic surfactants

Porous polymeric membranes made by polymerizing bicontinuous microemulsions stabilized with anionic sodium dodecyl sulfate (SDS) and cationic dodecyltrimethylammonium bromide (DTAB) as surface-active agents were investigated. The morphology, swelling and permeability characteristics of the membranes were found to be highly dependent on the surfactant concentration in both SDS and DTAB systems. The pore size of the DTAB system decreases on increasing the DTAB concentration, while the reverse trend was observed for the SDS system until its concentration exceeded 10 wt%. The membrane prepared using SDS was found to have a larger pore size in the range of 100 nm to 3 μm as compared to that of DTAB, which is less than 100 nm. In addition, the variation of SDS concentration led to a continuous change in the shape of particle aggregates of the membranes while it appeared to remain in globular form for the DTAB system. The remarkable differences between the membranes prepared using SDS and DTAB are discussed in terms of their different monolayer flexibilities.     

Synthesis and electrochemiluminescence studies of tricarbonylrhenium(I) complexes with a cationic 2,2′-bipyridyl ligand

Two new rhenium(I) carbonyl complexes with cationic 2,2′-bipyridyl ligands were synthesized and characterized. The electrogenerated chemiluminescence (ECL) of the rhenium(I) carbonyl complexes was first investigated in aqueous solution using the co-reactant tri-n-propylamine (TPrA). The ECL behavior of the complexes was also studied in the presence of several surfactants. The oxidation of both TPrA and the rhenium(I) complexes was facilitated in the presence of Triton X-100, and the ECL intensity was enhanced 300-fold at a Au electrode.     

Electrochemical synthesis of nickel hexacyanoferrate nanoarrays with dots, rods and nanotubes morphology using a porous alumina template

Transition metal hexacyanoferrate (MeHCF) have attracted extensive attention because of their outstanding properties including, electrocatalysis, molecular magnetism, biosensing and ion-exchange. This paper describes an approach for fabrication of ordered nanoarrays of Ni hexacyanoferrate (NiHCF) structures with different morphologies such as dots, rods and tubes in order to advance their properties and applications. The method is based on the conversion of Ni into NiHCF nanostructures by electrochemical oxidation in the presence of hexacyanoferrate ions, using nanoporous anodic alumina oxide (AAO) as a template. The structure and morphology of formed Ni and NiHCF nanoarrays were confirmed by scanning electron microscopy (SEM), showing agreement with the pore structures of the AAO template. The electrocatalytic activity of NiHCF nanorod array electrodes showed high catalytic properties for the detection of hydrogen peroxide and the potential to be used as a platform for direct biosensing applications. The ion-exchange ability of fabricated NiHCF nanostructures (nanorods and nanotubes) toward alkali cations such as Na⁺ has been successfully confirmed.     

Stability of foams containing proteins, fat particles and nonionic surfactants

The foamability of aqueous suspensions of proteins and fat particles containing different nonionic surfactants relevant to ice cream mix, through which air is continuously bubbled in a foam column, is investigated in terms of the growth of the foam until steady state is reached. Less water-soluble but more oil-soluble Spans 20, 80 and 85 (monolaurate, monooleate and trioleate of Sorbitan) reduced significantly the steady-state foam height and hence the foamability by enhancement of bubble coalescence. In contrast, highly water-soluble Tweens 20 and 80 increased only slightly the steady-state height of the foams as compared to that obtained using surfactant-free suspension. However, moderately water- and oil-soluble Tween 85 (polyoxyethylene sorbitan trioleate) decreased the foamability more significantly than the Spans. The bubbles are found to be small and coalesce relatively fast at the bulk air interface. The bridging of the fat particles by the three oleates could weaken the protein and fat network thereby reducing the elasticity of the air-aqueous phase interface. This is corroborated by the lowest interfacial elasticity measured using a biconical disc oscillatory rheometer. The stability of the foams formed is also determined by measuring the decrease in foam height and increase in mean bubble diameter with time after stopping the air flow. The results are found to verify a published theoretical model, which enabled to determine the parameters controlling foam stability. The Spans reduced the foam stability as the bubbles coalesced rapidly with bulk air. In contrast, the Tweens increased the foam stability as the bubbles coalesced very slowly. The increase of foam stability by Tween 85 under quiescent conditions is consistent with the measured high interfacial shear viscosity.     

Bordeaux-R interactions with surfactants: thermochromic investigations of proton ionisation in cationic, nonionic and anionic surfactant solutions

Apparent thermodynamic parameters for the hydroxy proton ionisation of Bordeaux-R were obtained in micellar solutions using the thermochromic method. The effect of addition of the surfactants CTAB, TX-100 and SDS was investigated in buffered solutions in the pH range of 6–13. Ionisation constants in water and in the presence of surfactants were determined spectrophotometrically and the p K ' of Bordeaux-R in water was found to be 10.90 in the absence of surfactant. However, at concentrations above critical micelle concentration, p K ' dropped to 10.14 with CTAB, increased to 11.29 with TX-100 but was insensitive to SDS addition. Standard enthalpies and entropies of ionisation were obtained using the thermochromic method. This method, in conjunction with p K and spectral measurements and comparison with different azo dyes, has been shown to provide detailed information on the mechanism of dye–surfactant interaction.     

Mesoporous MoS2 incorporated zirconia nanocomposites: Simple synthesis,characterization and photocatalytic desulfurization of thiophene under visible light

The petroleum sector has focused its efforts on developing low-sulfur fuels because of rigorous regulatory requirements enforced by various countries. In this context, mesoporous MoS₂/ZrO₂ nanostructures were simply manufactured and subsequently adopted under visible light for photocatalytic desulfurization of thiophene (PDT). Actually, PDT was extensively upgraded upon the application of MoS₂/ZrO₂ nanostructures especially when the results compared to pure ZrO₂. The pseudo-first-order model was the best model that was found to properly fit such a reaction. Amongst all manufactured specimens, the photocatalytic efficiency of the 1.5 wt% MoS₂/ZrO₂ nanostructured material was the maximum. The reaction rate of PDT upon utilizing optimized material was 0.01577 min^?1 whiles that upon the application of pure ZrO₂ was 0.000513 min^?1. And so, PDT rate was 30.5 times greater over 1.5 wt% MoS₂/ZrO₂ nanostructured material than over pure ZrO₂. The photocatalytic oxidation of thiophene over the manufactured materials yielded SO₃ and CO₂. The distinct photocatalytic effectiveness of MoS₂/ZrO₂ might be associated with the competent absorption of visible light, fast movement of thiophene molecules to active centres, expanded hydroxyl radical content and diminished light scattering. The recyclability test acknowledged that MoS₂/ZrO₂ nanostructured material was remarkably stable against PDT under visible light. The mechanism of the PDT reaction utilizing the photo-created charges was discussed.     

Solution combustion synthesis (SCS) of chrome alumina as a high temperature pink pigment

In this article, one step synthesis of the chrome alumina pink pigments is investigated. Results indicated that adjusting ignition parameters such as the fuel type (glycine, citric acid, and urea) and the oxidizer to fuel ratio, is the essential factor to obtain the straight corundum structure of the pigment. According to this, chrome alumina pink pigment was just synthesized by the urea fuel in 1.8 oxidizer to fuel (O/F) ratio. The effect of ignition parameters on the morphology was also studied. The microstructure was changed from ultra‐fine irregular agglomerates to sponge‐like flakes by the change in the fuel type from citric acid to urea. Colorimetric characteristics confirmed the relationship between the formation of the corundum structure and one step synthesis of the pink pigment. The pink color of synthesized pigments was comparable with commercial purplish pink pigments of tiles.     

Mixtures of anionic and cationic surfactants with single and twin head groups: Adsorption and precipitation studies

This research reports on the adsorption and precipitation of mixtures of anionic and cationic surfactants having single and twin head groups. The surfactant mixtures investigated were: (i) a single-head anionic surfactant, sodium dodecyl sulfate (SDS), in a mixture with the twin-head cationic surfactant pentamethyl-octadecyl-1,3-propane diammonium dichloride (PODD)—adsorption was studied on negatively charged silica; and (ii) a twin-head anionic surfactant, sodium hexadecyl-diphenyloxide disulfonate (SHDPDS), and the single-head cationic surfactant dodecylpyridinium chloride (DPCI)—adsorption was studied on positively charged alumina. Whereas the mixed surfactant system of SHDPDS/DPCI showed adsorption on alumina that was comparable to the of SHDPDS alone, the mixed surfactant system of SDS/PODD showed increased adsorption on silica as compared with PODD alone. The adsorption of the SDS/PODD mixture increased as the anionic and cationic system approached an equimolar ratio. Precipitation diagrams for mixtures of single- and twin-head surfactant systems showed smaller precipitation areas than for single-head-only surfactant mixtures. Thus, the combination of single- and double-head surfactants helps reduce the precipitation region and can increase the adsorption levels, although the magnitude of the effect is a function of the specific surfactants used.     

Polyoxymethylene/polyurethane/alumina ternary composites: Structure,mechanical, thermal and dielectric properties

Ternary composites composed of polyoxymethylene (POM), polyurethane (PU), and boehmite alumina were produced by melt blending with and without latex precompounding. Latex precompounding served for the predispersion of the alumina particles. The related masterbatch (MB) was produced by mixing the PU latex with water‐dispersible boehmite alumina. The dispersion of the alumina was studied by transmission and scanning electron microscopy techniques (TEM and SEM, respectively) and discussed. The crystallization of POM was inspected by means of differential scanning calorimetry (DSC) and polarized optical microscopy (DSC and polarized light microscopy, respectively). The mechanical and thermomechanical properties of the composites were determined in uniaxial tensile, dynamic‐mechanical thermal analysis (DMTA), short‐time creep tests (performed at various temperatures), and thermogravimetric analysis (TGA). The melt flow of the composites was characterized in a plate/plate rheometer. In addition, the dielectric response of the nanocomposites was investigated by means of broadband dielectric spectroscopy at an ambient temperature. The composites produced by the MB technique outperformed the direct melt (DM) compounded composites in respect to the thermal and mechanical characteristics. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

The preparation and characterization of urushiol powders (YPUOH) based on urushiol

Urushiol and lacquer sap from lacquer tree exhibit good antimicrobial and antioxidant properties. However, they are limited to commercial application due to their high volatility, low drying rate and allergic reaction. To overcome these limitations, solid-type urushiols (YPUOH), which is one of the essential factors for convenient handling in various industrial fields such as functional additives for paints, coating and composite films, were successfully prepared with urushiol and TPM. The reaction mechanism between urushiol and silane coupling agent has been evaluated based on Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR). As-prepared YPUOH powders exhibited excellent antibacterial activity against E. coli and S. aureus, good antioxidant activity, and high thermal stability.     

Synthesis and surface-active properties of trimeric-type anionic surfactants derived from tris(2-aminoethyl)amine

Trimeric-type anionic surfactants (3C_ntaAm, where n is a hydrocarbon chain length of 8, 10, or 12) with three hydrocarbon chains and three carboxylate headgroups were synthesized from tris(2-aminoethyl)amine, and their properties were investigated by surface tension, electrical conductivity, dynamic and static light-scattering, fluorescence of pyrene, and emulsification power techniques. The critical micelle concentrations (CMC) of 3C_ntaAm were 0.00092–0.00834 mmol dm⁻³, and the surface tensions at the CMC were 33.3–39.9 mN m⁻¹. The areas per molecule occupied by 3C₁₀taAm and 3C₁₂taAm were extremely small, showing they were highly compact at the air/water interface. In addition, adsorption or micellization behavior of 3C_ntaAm was estimated by parameters such as pC ₂₀ (the efficiency of surface adsorption), CMC/C ₂₀ (the ease of adsorption relative to the ease of micellization), and ΔG _M ^o (Gibbs energy of micellization). Dynamic and static light-scattering mesurements of 3C_ntaAm showed a hydrodynamic radius of 45–61 nm above the CMC and aggregation numbers of 10–82 at the CMC, respectively. The fluorescence intensity ratio of the first to the third band in the emission spectra of pyrene started to lower from far above the CMC for 3C₈taAm and 3C₁₀taAm, and below the CMC for 3C₁₂taAm. This suggests that loose micelles or premicellar aggregates are formed in solutions. Mixtures of aqueous solutions of 3C_ntaAm and toluene formed oil-in-water-type emulsions, and the stabilizing abilities were in the order of 3C₈taAm>3C₁₀taAm>3C₁₂taAm. The degree of emulsification of 3C₈taAm remained at 69% after 24 h of standing. Thus, 3C_ntaAm exhibited unique properties superior to monomeric or dimeric surfactants that were significantly influenced by their hydrocarbon chain lengths.