Water In Hexane Research Articles

Role of silane grafting in the development of a superhydrophobic clay-alumina composite membrane for separation of water in oil emulsion

Hydrophobic composite kaolin-coated clay-alumina membranes are unique choices for water in oil emulsion separation. In this work, a membrane fabrication approach is presented using kaolin clay coating in the clay-alumina tubular composite support tube and subsequently grafting by different concentrations of fluoroalkyl silane (FAS: 1H, 1H, 2H, 2H, -Perfluorooctyltriethoxysilane) on the membrane surface. Different concentrations of fluoroalkyl silane formed distinctive hierarchical structures which exhibited hydrophobicity of the membrane surface. The pore property, surface roughness properties, and thermogravimetric properties can be suitably tailored by tuning the silane concentration in the grafting solution. The surfaces of comparatively higher silane content grafted (M50 and M100) composite membranes were found to be superhydrophobic. Comparably, our optimal composite membrane (M100) displayed a moderate steady flux rate of 80-100LMH (Lm−2h −1) and excellent water rejection (>99%) properties during the separation of water in hexane and toluene emulsion at a cross-flow transmembrane pressure of 1 bar. The role of silane concentration on permeated hexane and toluene flux rate, water rejection rate, surface wettability, microstructure, and hydrophobic stability reveals new distinguishing insights into the hydrophobic clay-alumina composite membrane fabrication.

Oxidizing Cerium(IV) Alkoxide Complexes Supported by the Kläui Ligand [Co(η5-C5H5){P(O)(OEt)2}3]-: Synthesis, Structure, and Redox Reactivity.

Tetravalent cerium alkoxide complexes supported by the Kläui tripodal ligand [Co(η5-C5H5){P(O)(OEt)2}3]- (LOEt-) have been synthesized, and their nucleophilic and redox reactivity have been studied. Treatment of the Ce(IV) oxo complex [CeIV(LOEt)2(O)(H2O)]·MeCONH2 (1) with iPrOH or reaction of [CeIV(LOEt)2Cl2] (2) with Ag2O in iPrOH afforded the Ce(IV) dialkoxide complex [CeIV(LOEt)2(OiPr)2] (3-iPr). The methoxide and ethoxide analogues [CeIV(LOEt)2(OR)2] (R = Me (3-Me), Et (3-Et)) have been prepared similarly from 2 and Ag2O in ROH. Reaction of 3-iPr with an equimolar amount of 2 yielded a new Ce(IV) complex that was formulated as the chloro-alkoxide complex [CeIV(LOEt)2(OiPr)Cl] (4). Treatment of 3-iPr with HX and methyl triflate (MeOTf) afforded [Ce(LOEt)2X2] (X- = Cl-, NO3-, PhO-) and [CeIV(LOEt)2(OTf)2], respectively, whereas treatment with excess CO2 in hexane led to isolation of the Ce(IV) carbonate [CeIV(LOEt)2(CO3)]. 3-iPr reacted with water in hexane to give a Ce(III) complex and a Ce(IV) species, presumably the reported tetranuclear oxo cluster [CeIV4(LOEt)4(O)5(OH)2]. The Ce(IV) alkoxide complexes are capable of oxidizing substituted phenols, possibly via a proton-coupled electron transfer pathway. Treatment of 3-iPr with ArOH afforded the Ce(III) aryloxide complexes [CeIII(LOEt)2(OAr)] (Ar = 2,4,6-tri-tert-butylphenyl (5), 2,6-diphenylphenyl (6)). On the other hand, a Ce(III) complex containing a monodeprotonated 2,2'-biphenol ligand, [CeIII(LOEt)2(tBu4C12H4O2H)] (7) (tBu4C12H4O2H2 = 4,4',6,6'-tetra-tert-butyl-2,2'-biphenol), was isolated from the reaction of 3-iPr with 2,4-di-tert-butylphenol. The crystal structures of complexes 3-iPr, 3-Me, 3-Et, and 5-7 have been determined.

Nanostructured Materials via the Pendant Self-Assembly of Amphiphilic Crystalline Random Copolymers.

Versatile self-assembly systems to nanostructured materials in both solid and solution were developed with common amphiphilic random copolymers bearing hydrophilic poly(ethylene glycol) (PEG) and hydrophobic crystalline octadecyl pendants. The copolymers efficiently induced precision self-assembly of the pendants to provide not only core-crystalline, thermoresponsive micelles and vesicles in water and reverse micelles in hexane but also sub-10 nm lamellar or spherical microphase separation structure in solid. Typically, the solid random copolymers with 50-80 mol % octadecyl units formed lamellar structure of a hydrophilic PEG layer and a hydrophobic, crystalline octadecyl layer. Importantly, the domain spacing is about 5 nm, much smaller than that generally obtained with conventional block copolymers. The domain structure is controlled by composition, independent of chain length. The copolymers further gave various thermoresponsive, compartmentalized materials in aqueous and organic media, where the 3D structure can be also controlled by the composition and sample preparation protocols.

Synthesis of Size-controlled Luminescent Si Nanocrystals from (HSiO1.5)nPolymers

Size control (1–10 nm) of Si nanocrystals was simply achieved by thermal pyrolysis of (HSiO1.5)n polymers synthesized with different ratios of network-to-cage structures by reaction of trichlorosilane with water in hexane. Different sized nanocrystals exhibited visible photoluminescence (λ = 400–700 nm) at different wavelengths after chemical etching and surface passivation.

English

Moringa oleifera Lamk. (Moringaceae) is a very usef ul tree in tropical countries. In folklore and ayurvedic all parts of the tree used in different h ealing procedures for different diseases. The plant leaves are very good nutrient supplement for malnut rition and also used as an antimicrobial agent. The crude aqueous and alcoholic leaf extract of Mor inga oleifera was subjected to phyto-chemical analysis to determine the constituents of the leaf extracts. Results of phyto-chemical analysis showed that the crude extracts contained Carbohydrates, Pr oteins, Resins, Tannin and Alkaloids. The chemical compounds found in these extracts of Morin ga oleifera leaf have good pharmacological properties. The Solubility of Moringa leaf with nin e solvents, results highest in water (32%) and lowest in Hexane (5.0 %) solvent. The antimicrobial activity of the Moringa leaf was assayed against one Gram- positive strains ( Staphylococcus aureus) , two Gram-negative strains (Escherichia coli, Pseudomonas aeruginosa), and five fungal strains of agro-food interest (Penicillium aurantiogriseum, Penicillium expansum, Penicillium citrinum, Penicillium digitatum, and Aspergillus niger spp.). Staphylococcus aureus, E .coli as well as the fungal strains were sensitive to the Moringa leaf extract . The traditional appli cation of the leaf of Moringa oleifera as poultice and decoction may have a scientific or pharmacologi cal basis. These studies provide an evidence to support traditional medicinal uses of the plant.

Enhanced desalination performance of polyamide bi-layer membranes prepared by sequential interfacial polymerization

A novel thin film composite (TFC) membrane featuring a polyamide bilayer was prepared on a porous polysulfone support using sequential interfacial polymerization. A conventional polyamide membrane prepared using m-phenylenediamine (MPD) in water and trimesoyl chloride (TMC) in hexane via interfacial polymerization was subsequently immersed into an alkaline aqueous solution of a hexafluoroalcohol (HFA)-containing aromatic diamine (HFA-MDA) to form an HFA-substituted aromatic polyamide layer (HFAPA) on the surface of the conventional (or reference) polyamide layer (REFPA). Water contact angle (θw) measurements indicated that the surface of the membrane becomes much more hydrophobic (θw≅140°) after forming the additional HFAPA layer onto REFPA (θw≅78°) although cross-sectional TEM images showed no significant increment in film thickness. The HFAPA-on-REFPA bilayer membrane, which features a more hydrophobic surface than the conventional REFPA membrane, exhibited improved salt rejection (ca. 50% reduction in salt passage) with a small loss in water flux (ca. 8% reduction) compared to the REFPA membrane, resulting in an excellent combination of salt rejection and water flux. Moreover, higher boron rejection was also achieved using the bilayer membrane (HFAPA-on-REFPA) compared to the REFPA membrane.

Detecting trace amounts of water in hydrocarbon matrices with infrared fiberoptic evanescent field sensors

Water is a common contaminant in a variety of industrial oils and petroleum products. Thus, the detection of water in these products is of substantial relevance. Hence, this study focuses on quantifying trace amounts of water in hydrocarbons using hexane as a model system for industrial oils and petroleum matrices via mid-infrared (MIR) evanescent field absorption spectroscopy. A silver halide fiberoptic waveguide was used to interrogate in situ water-in-hexane emulsions. Either unmodified fibers or waveguides surface-modified with polyacrylic acid layers were used. The limits of detection (LOD) and limits of quantification (LOQ) of water in hexane utilizing tin-crosslinked polyacrylic acid modified fibers were 76 and 170 ppm, respectively. Consequently, the IR absorption signature of water in hexane is detectable at concentrations as low as 10 ppm. The proposed fiberoptic sensing strategy requires a single measurement only, requires no sample preparation, and thus has potential for the direct in situ detection and monitoring of water in industrial oils and petroleum products.

One-Pot Reduction of Sulfoxides with NaBH4, CoCl2 · 6H2O Catalyst, and Moist Alumina

Sulfoxides are reduced by a combination of sodium borohydride, a catalytic amount of cobalt(II) chloride hexahydrate, and chromatographic neutral alumina preloaded with a small amount of water (moist alumina) in hexane to produce the corresponding sulfides in good to excellent yields under mild conditions. An interesting structural influence of sulfoxides on their reactivity is observed.

One-Pot System for Reduction of Epoxides Using NaBH4, PdCl2 Catalyst, and Moist Alumina

Reduction of epoxides with sodium borohydride, a catalytic amount of palladium(II) chloride, and chromatographic neutral alumina preloaded with a small amount of water (moist alumina) in hexane gave alcohols in good to excellent yields and good selectivity of the desired products under mild conditions. The reaction system was operationally simple and environmentally friendly. The alumina can be recovered simply and reused a number of times without any treatment and with good activity.

Lithium complexes supported by amine bis-phenolate ligands as efficient catalysts for ring-opening polymerization of l-lactide

Lithium complexes bearing dianionic amine bis(phenolate) ligands are described. Reactions of ligand precursors H(2)O(2)NN(Me), H(2)O(2)NN(Py) or H(2)O(2)NO(Me) [H(2)O(2)NN(Me)=Me(2)NCH(2)CH(2)N-(CH(2)-2-HO-3,5-C(6)H(2)((t)Bu)(2))(2); H(2)O(2)NN(Py)=(2-C(5)H(4)N)CH(2)N-(CH(2)-2-HO-3,5-C(6)H(2)((t)Bu)(2))(2); H(2)O(2)NO(Me)=MeOCH(2)CH(2)N-(CH(2)-2-HO-3,5-C(6)H(2)((t)Bu)(2))(2)] with 2.2 molar equivalents of (n)BuLi in diethylether afford (Li(2)O(2)NN(Me))(2) (1), (Li(2)O(2)NN(Py))(2) (2) and (Li(2)O(2)NO(Me))(2) (3) as tetra-nuclear lithium complexes. The crystalline solids of partially hydrolyzed product, (LiO(HO)NN(Py)) (4), were obtained from recrystallization of 2 in diethylether solution for three months. The synthesis of (LiO(HO)NO(Me))(2) (5) was carried out at ambient temperature by carefully layering a solution of water in hexane on top of a solution of 3 in Et(2)O. Crystalline solids of were obtained after two months. Molecular structures are reported for compounds 1, 3, 4 and 5. Compounds 1-3 show excellent catalytic activities toward the ring-opening polymerization of L-lactide in the presence of benzyl alcohol.

Multivariate Analysis of ATR−IR Spectroscopic Data: Applications to the Solid−Liquid Catalytic Interface

It is demonstrated that attenuated total reflection infrared (ATR-IR) spectroscopy coupled with multivariate data analysis can be effectively used for in situ investigation of supported catalyst-liquid interfaces. Both formaldehyde adsorption/dissociation in water and acetonitrile adsorption in hexane on thin (ca 10 mum) films of 5 wt % Pt/gamma-Al(2)O(3) deposited on a germanium waveguide have been investigated. The multivariate analysis applies classical least squares (CLS) and partial least squares (PLS) methods to the ATR-IR data in order to correlate spectral changes with known sources of experimental variation (i.e., time, concentration of solution species, etc.). The formaldehyde adsorption experiments revealed no spectroscopic evidence for adsorbed molecular formaldehyde under the conditions examined. However, the dissociation product carbon monoxide was observed to form in atop configuration on Pt, likely on edges and terrace sites. Isotope labeling experiments suggest that a pair of peaks observed at 1990 and 2060 cm(-)(1) during treatments of Pt in H(2)-saturated water arise at least in part from nu(Pt)(-)(H) stretching of adsorbed atomic hydrogen. Acetonitrile was found to adsorb on the Pt catalyst by sigma-bonding of the CN group with the platinum, yielding apparent surface peaks that are almost identical to that observed in the liquid phase. A peak at 1641 cm(-)(1) was observed which was assigned to the adsorption of the CN group in a tilted configuration involving a combination of end-on and pi interaction with the surface. This species was found to be reactive toward hydrogen, suggesting that it might play a role in nitrile hydrogenation. The prospects of using this approach to examine solid-catalyzed liquid-phase reactions are discussed in light of these findings.

Purple or Colorless - Which Way Up? An Entertaining Solubility Demonstration

An entertaining demonstration is described that illustrates concepts of solubility and relies on the fact that solutions of potassium permanganate in water and iodine in hexane are indistinguishable to the eye.

A New Way to Prepare Nanostructured Materials: Flame Spraying of Microemulsions

In this report we describe a new method to obtain nanostructured coatings or powders based on the flame decomposition of microcompartmentalized solutions. Metal nanoclusters of well-defined size are obtained by reduction of a metal salt inside the water compartment of water in oil (w/o) microemulsions, formed by water in hexane and stabilized by an appropriate surfactant. Metal nanoclusters can be separated from the mother solution by spraying the microemulsion solution into an air/acetylene flame. In this way, nanostructured coating or powder, almost preserving the original structure of the nanoparticles synthesized in the microemulsion system, can be obtained in quantities sufficient for industrial applications. As an example we report the flame spraying of gold microemulsions to produce gold coating onto silicon wafers. To the best of our knowledge, this study reports a new method allowing the use of a microemulsion synthetic pathway for the production of consistent amount of nanoparticles. This method could be of great utility in many applications involving nanoparticles in the fields of physics, chemistry, biotechnology, and biology.

Synthesis and Characterization of Nanocrystalline Bismuth Telluride

We report the first synthesis and characterization of nanocrystalline Bi2Te3 with particle sizes less than 10 nm. The reaction of BiOClO4·xH2O with (Me3Si)2Te in a reverse micelle formed by sodium dioctylsulfosuccinate and water in hexane has produced good yields (71%) of a black powder that has been characterized by elemental analysis, X-ray diffraction, and transmission electron microscopy.

Preparation of a microporous cell by dissolution of core particles within a core-shell-type composite powder—preparation of titania or silica microporous cells

Core-shell-type composite powders were prepared by hydrolysis of titanium tetraisopropoxide or tetraethyl orthosilicate in a dispersion of core particles adsorbed with water in hexane. Microporous cells could be made of the composite powder dissolved within the core particles in acetic acid solution. The content of titania in BaCO 33-TiO 2 composite powder was controlled by the amount of water adsorbed. The pore volume of the microporous cell changed with the content of titania. BaCO 3-TiO 2 composite powder was heated at 600°C for 10 h and barium ions in the core particles were diffused to titania. Thus, microporous cells composed of the BaTiO 3 ultrafine particles were prepared.

コア・シェル型複合粒子の芯粒子溶解による中空粒子の調整 チタニア，シリカ中空粒子の調製

A core-shell type composite powder was prepared by the hydrolysis of titanium tetraisopropoxide or ethyl silicate in the dispersion of BaCO3 core particles which adsorbed water in hexane. Core particles of the composite powder were dissolved in acetic acid solution, and micro porous cells were thus obtained.The content of titania in the BaCO3-TiO2 composite powder was controlled by the amount of water adsorbed. The pore volume of the micro porous cells increased with the titania content of the composite powder after the dissolution of the core particles.The BaCO3-TiO2 composite powder was heated at 600°C for 10 hours, and barium ions in core particles were diffused to titania. The micro porous cells composed of the BaTiO3 ultra-fine particles were thus created after the BaCO3 core particles were dissolved.

Interesterification of Butter Fat by Lipase fromMucor mieheiin Organic Solvent Media

Summary Butter fat was interesterified in three organic solvent media, hexane, hexane‐chloroform (70:30, v/v), and hexane‐ethyl acetate (70:30, v/v), at different water contents, using commercial immobilized lipase from Mucor miehei. The results indicate that the addition of 30% of either chloroform or ethyl acetate to the hexane resulted in a 25% increase in the interesterification yield; moreover, the addition of 0.8 to 1% water shifted the hydrolytic affinity of lipase towards low molecular weight fatty acids. However, the addition of a small portion of water in hexane, 0.4%, increased the amount of free fatty acids from 0.30 to 7.98 mmole per gram of butter.

Spontaneous emulsification in the system sodium dodecyl sulfate in water and cholesterol in hexane

Among the different mechanisms for spontaneous emulsification, in the present system the occurrence of a low interfacial tension applies. The region at which spontaneous emulsification occurs was obtained by extrapolation of interfacial tension—concentration curves and agrees with direct observation. The reason of this low interfacial tension is due to an interaction between both surfactants, where interchain penetration plays a role.

Diffusion in polymers

AbstractConcentration dependent diffusion coefficients explain Case II type diffusion. Solutions to the diffusion equation yield straight lines for weight gain vs time when the exponential variation of the diffusion coefficient is included. Boundary layer resistance together with concentration dependent diffusion coefficients explain Super Case II type diffusion. The increase in the rate of weight gain after a prolonged period is predictable. The surface concentration rises slowly to its equilibrium value in this case. Boundary layer resistance appears to be quite common, particularly where the penetrant has low affinity (not a true solvent) for the polymer, such as water in most polymers or hexane in polystyrene. Boundary layer resistance is quite significant for coatings (where film thicknesses are usually measured in microns), accounting for the majority of the resistance in some cases. A method to separate diffusional resistance from the surface resistance is suggested, but studies at different film thicknesses appear mandatory.

Compartmentalization of amino acids in surfactant aggregates. Partitioning between water and aqueous micellar sodium deodecanoate and between hexane and dodecylammonium propionate trapped water in hexane.

Cationic amino acids, arginine and lysine partition differentially from water into aqueous micellar sodium dodecanoate. Conversely, partitioning of serine, glycine, aspartic acid, glutamic acid, threonine, alanine, proline, valine, leucine, phenylalanine and isoleucine do not vary appreciably. Partitioning from neat hexane into dodecylammonium propionate trapped water in hexane is, however, dependent upon both electrostatic and hydrophobic interactions. These results imply that the interior of dedecylammonium propionate aggregates is negatively charged and is capable of hydrogen bonding in addition to providing a hydrophobic enviroment. The solubilities of amino acids in neat hexane substantiate the previously derived amino acid hydrophobicity scale. Relevance of partitioning in these systems to the postulated selective amino acid compartmentalization is discussed.