Showing papers on "Hexane published in 2013"
TL;DR: Fe2(BDP)3 (BDP2– = 1,4-benzenedipyrazolate), a highly stable framework with triangular channels that effect the separation of hexane isomers according to the degree of branching is reported, showing preliminary promise for enhancing a separations process central to gasoline production.
Abstract: Metal-organic frameworks can offer pore geometries that are not available in zeolites or other porous media, facilitating distinct types of shape-based molecular separations. Here, we report Fe2(BDP)3 (BDP(2-) = 1,4-benzenedipyrazolate), a highly stable framework with triangular channels that effect the separation of hexane isomers according to the degree of branching. Consistent with the varying abilities of the isomers to wedge along the triangular corners of the structure, adsorption isotherms and calculated isosteric heats indicate an adsorption selectivity order of n-hexane > 2-methylpentane > 3-methylpentane > 2,3-dimethylbutane ≈ 2,2-dimethylbutane. A breakthrough experiment performed at 160°C with an equimolar mixture of all five molecules confirms that the dibranched isomers elute first from a bed packed with Fe2(BDP)3, followed by the monobranched isomers and finally linear n-hexane. Configurational-bias Monte Carlo simulations confirm the origins of the molecular separation.
551 citations
TL;DR: This study provides a new prospect to simply introduce multiple molecules on the adhesive PDA-based mesh to achieve various functional oil/water separation materials.
Abstract: An oil/water separation mesh with high separation efficiency and intrusion pressure of water has been successfully developed by combining mussel-inspired chemistry and Michael addition reaction. The substrate of the stainless steel mesh was first coated with the adhesive polydopamine (PDA) film by simple immersion in an aqueous solution of dopamine at pH of 8.5. Then n-dodecyl mercaptan (NDM) was conjugated with PDA film through Michael addition reaction at ambient temperature. The as-prepared mesh showed highly hydrophobicity with the water contact angle of 144° and superoleophilicity with the oil contact angle of 0°. It can be used to separate a series of oil/water mixtures like gasoline, diesel, etc. The separation efficiency remains high after 30 times use (99.95% for hexane/water mixture). More importantly, the relatively high intrusion pressure (2.2 kPa) gives the opportunity to separation of large amount of oil and water mixtures. This study provides a new prospect to simply introduce multiple mole...
296 citations
TL;DR: In this article, a combination of solvent extraction and adsorption on solids was used for the recovery of base oils from waste lubricants, and the results showed that 1-butanol achieved the best performance with the maximum percent sludge removal, followed by n-hexane, petroleum ether, 1hexanol, carbon tetrachloride, and acetone.
112 citations
TL;DR: In this paper, imidazolium-based ionic liquids (ILs) were used to extract phenol from a model oil of hexane and phenol in order to reduce environmental risk.
Abstract: Phenolic compounds, which are important substances in industry, are mainly derived from coal liquefaction oil, coal tar, and petroleum, and also from biomass via pyrolysis. However, the traditional process of separation of phenols from oil using water, NaOH, and H2SO4 causes serious environmental problems. In this work, imidazolium-based ionic liquids (ILs) were used to extract phenol from a model oil of hexane and phenol in order to reduce environmental risk. It was found that these ILs could successfully separate phenols from hexane, and a small amount of [Bmim]Cl, equimolar to that of phenol in hexane, was enough to extract phenol with a high extraction efficiency of 99%. Anions of imidazolium-based ILs have a significant influence on the phenol extraction efficiency, which follows the order: Cl– > Br– > BF4– > PF6–. But the cation of these ILs shows a relatively small influence on the extraction. Particularly, [Bmim]Cl shows best performance in terms of phenol extraction efficiency. Furthermore, it is...
98 citations
TL;DR: In this article, four tailor-made flat composite membranes of poly(vinylideneflouride) (PVDF) as a support and polydimethylsiloxane (PDMS) or cellulose acetate (CA) as coating layer, and a commercially available composite membrane (Solsep 030306) were used to remove hexane and free fatty acid (FFA) from crude soybean oil-hexane mixture.
89 citations
TL;DR: In this article, the authors investigated the effect of particle size diameter, type of solvent and solvent to solid ratio on the kinetic and thermodynamic parameters; entropy, enthalpy and free energy of extraction.
86 citations
TL;DR: The results prove the potential of ZIF-8 as a new adsorbent that can be employed in the upgrade of the Total Isomerization Process for the production of high octane number gasoline, by blending di-branched alkanes in the gasoline.
Abstract: We study the adsorption equilibrium isotherms and differential heats of adsorption of hexane isomers on the zeolitic imidazolate framework ZIF-8. The studies are carried out at 373 K using a manometric set-up combined with a micro-calorimeter. We see that the Langmuir model describes well the isotherms for all four isomers (n-hexane, 2-methylpentane, 2,2-dimethylbutane and 2,3-dimethylbutane). The linear and mono-branched isomers adsorb well, but 2,2-dimethylbutane is totally excluded. Plotting the differential heat of adsorption against the loading shows an initial plateau for n-hexane and 2-methylpentane. This is followed by a slow rise, indicating adsorbate-adsorbate interactions. For the di-branched isomers the differential heat of adsorption decreases with loading. To gain further insight, we ran molecular simulations using the grand-canonical Monte Carlo approach. Comparing the simulation and the experimental results shows that the ZIF framework model requires blocking of the cages, since 2,2-dimethylbutane cannot fit through the sodalite-type windows. Practically speaking, this means that ZIF-8 is a highly promising candidate for enhancing gasoline octane numbers at 373 K, as it can separate 2,2-dimethylbutane and 2,3-dimethylbutane from 2-methylpentane. Our results prove the potential of ZIF-8 as a new adsorbent that can be employed in the upgrade of the Total Isomerization Process for the production of high octane number gasoline, by blending di-branched alkanes in the gasoline.
77 citations
TL;DR: In this paper, response surface methodology (RSM) was used to optimize the biodiesel production from palm oil under supercritical ethanol conditions, which enabled simultaneous transesterification of triglycerides and ethyl esterification of fatty acids in a shorter reaction time and may reduce energy consumption due to simplified separation and purification steps.
73 citations
TL;DR: In this article, the authors investigated the chemical composition of sour cherry seeds in depth for potential utilization as a source of oil, protein and dietary fibers, and found that the kernel contained 170% of the oil, 293% of proteins and 303% of dietary fibers.
73 citations
TL;DR: The use of iridium pincer catalysts for the hydrosilylative reduction of sugars is examined, and complete reduction of silyl-protected glucose to a mixture of hexane isomers is reported.
Abstract: In light of diminishing petroleum feedstocks, there is significant interest in developing carbohydrate defunctionalization reactions In this context we have examined the use of iridium pincer catalysts for the hydrosilylative reduction of sugars, and we report herein complete reduction of silyl-protected glucose to a mixture of hexane isomers
69 citations
TL;DR: Porous polybenzimidazole networks (PBI-1 and PBI-2) as mentioned in this paper were synthesized through a one-step polycondensation of 3,3′-diaminobenzidine with tris(4-carboxyphenyl)amine and tetrakis(3,4)-silane, respectively.
TL;DR: In this paper, the use of liquid dimethyl ether (DME) as a solvent for extracting hydrocarbons and lipids from Botryococcus braunii Race B paste was proposed.
TL;DR: In this paper, the photocatalytic degradation of three VOCs differing in chemical structure (n -hexane, n -butyl acetate and toluene) in a closed-loop reactor was investigated.
TL;DR: In this article, low transition temperature mixtures (LTTMs) were evaluated as extractant solvents for the separation of benzene from hexane (aromatic/aliphatic mixture) and ethyl acetate and hexane, which are both azeotropic systems.
TL;DR: In this article, the effects of co-pyrolysis of Kukersite oil shale and pine ( Pinus sylvestris ) sawdust were studied in autoclaves in the ranges of blend composition x i ǫ = 0-1/g/g, nominal temperature 360-400°C and duration 2-4 h. The amplitude of Δ was explained based on the stability of a new crosscompound A n B formed between the liquid and solid decomposition products of the components.
TL;DR: The absence of inhibition of hexane biodegradation by substrate competition confirmed that hexane removal in the MBR was indeed limited by the mass transfer through the membrane.
TL;DR: In this article, the performance of IL-solvent mixtures instead of pure ILs as extractant was systematically studied, and it was found that a mixture of IL and acetonitrile can be beneficial since it avoids cross-contamination which is usually a problem with conventional solvents.
TL;DR: Simulation points suggest that uranyl complexation by amide ligands occurs "right at the interface", displaying marked analogies with the liquid-liquid extraction of uranyl by TBP (tri-n-butyl phosphate).
Abstract: We report a molecular dynamics study of biphasic systems involved in the liquid–liquid extraction of uranyl nitrate by a monoamide ligand (L = N,N-di(2-ethylhexyl)isobutyramide, DEHiBA) to hexane, from pH neutral or acidic (3 M nitric acid) aqueous solutions. We first describe the neat interfaces simulated with three electrostatic models, one of which including atomic polarizabilities. The free energy profiles for crossing the water/hexane interface by L or its UO2(NO3)2L2 complex are then investigated by PMF (potential of mean force) calculations. They indicate that the free ligand and its complex are surface active. With the polarizable force field, however, the complexes have a lower affinity for the interface than without polarization. When DEHiBA gets more concentrated and in acidic conditions, their surface activity diminishes. Surface activity of UO2(NO3)2L2 complexes is further demonstrated by demixing simulations of randomly mixed DEHiBA, hexane, and neutral or acidic water. Furthermore, demixing...
TL;DR: Despite the non-quantitative extraction of polycyclic aromatic hydrocarbons from oil using acetonitrile, the signal-to-noise ratio was significantly improved obtaining a limit of detection largely below the performance criteria required by the European Union legislation.
TL;DR: A series of functionalized porous Zr terephthalate MOFs of the UiO-66(Zr) structure type bearing either Br, NH 2 or NO 2 groups have been synthesized at the multi-gram scale through an atmospheric pressure solvothermal route with the final aim of investigating the influence of functionalization on the separation of hexane isomers.
TL;DR: In this article, the ionic liquids 1-butyl-1-methylpyrrolidinium dicyanamide, [BMpyr][N(CN)2], and 1 -butyl 1-methyl pyrrolidsinium trifluoromethanesulfonate (TfO), were studied as green solvents for the separation of ethanol from heptane and hexane.
TL;DR: In this paper, a kinetic study of n-hexane cracking over MFI-type zeolite was conducted in the temperature range from 748 to 923 K using a fixed-bed flow reactor under atmospheric pressure.
TL;DR: In this paper, a zeolite beta-silicalite-1 composite was prepared by growing polycrystalline silicalite shells on single micron-sized Zeolite Beta crystals, which was employed for the separation of hexane isomers.
TL;DR: In this article, the influence of the aluminium content on the adsorption of hexane isomers at 293 K on MFI type zeolites (Si/Al ratios - SAR of 25, 100 and infinity) was investigated with a home-made volumetric system.
15 Nov 2013
TL;DR: The interfacial tensions of aqueous solutions against different oil phases are measured using drop profile analysis tensiometry (PAT-1) for decyl- and dodecyltrimethylammonium bromide and the obtained equilibrium interfacial tension isotherms were fitted by the Frumkin Ionic Compressibility model.
Abstract: We measured the interfacial tensions of aqueous solutions against different oil phases using drop profile analysis tensiometry (PAT-1, Sinterface Technologies, Germany) for decyl- and dodecyltrimethylammonium bromide (C10TAB and C12TAB) in phosphate buffer (10 mM, pH7). The following alkanes were used as oil phases: hexane, heptane, octane, nonane, decane, dodecane and tetradecane. The obtained equilibrium interfacial tension isotherms were fitted by the Frumkin Ionic Compressibility model (FIC). The surfactants adsorb at the water/oil interface in competition with the oil molecules. At high surfactant surface coverage this competitive adsorption is manifested in two ways. First, for short chain surfactants, the oil molecules are embedded into the adsorption layer. Second, for long chain surfactants, the short alkane chains of the oil molecules are squeezed out from the adsorption layer due to strong mutual interaction between surfactants' chains.
TL;DR: In this paper, the degradation of gas-phase hexane in air streams by immobilized nanoparticles of TiO 2 and ZnO onto Perlite and Poraver® granules was studied.
TL;DR: It was found that the overwhelming majority of pesticides are hydrophobic, and n-hexane can be used for selective and efficient extraction and preconcentration of pesticides from water matrices, and acetonitrile is effective forThe distribution constants described in the paper may be effectively used for the estimation of possibilities of extraction isolation, preconcentrations and separation of pesticides.
TL;DR: In this paper, a salt effect-aided aqueous extraction process (AEP-SE) was used for extracting Camellia oleifera seed oil (COSO) to improve oil extractability and avoid emulsification.
Abstract: Aqueous extraction is a promising green alternative to hexane extraction. This study used a salt effect-aided aqueous extraction process (AEP-SE) for extracting Camellia oleifera seed oil (COSO) to improve oil extractability and avoid emulsification in the aqueous system. The highest oil extractability rate of 88.8% was obtained under 1.48 mol L –1 sodium carbonate, a solution-to-flour ratio of 3.85, and 3.23h of extraction time with the quality of the aqueous system-extracted oil being similar to those of a commercial sample of COSO and hexane-extracted oil in terms of color, iodine value and saponifcation value, although its moisture content was higher. Furthermore, the free fatty acid content of the aqueous system-extracted oil was lower than that of the solvent-extracted oil. The values of the inibihitory concentration at 50% of oil obtained by AEP-SE and organic solvent extraction as measured by DPPH scavenging activity essay, were 2.27 mg/mL and 3.31 mg/mL. AEP-SE is therefore a promising environmentally friendly method for the large-scale preparation of COSO.
TL;DR: The efficiency of the process, measured through the recoveries from spiked samples of edible oil was higher than 95% and the procedure has been applied to determine mineral oil in olive oil from the retailed market.
TL;DR: In this article, the roles of valence electrons in annihilation process for gas and liquid phases of hexane have been recognized for the first time in the present study, which is again in agreement with liquid phase measurement.