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Siavash Darvishmanesh Thomas Robberecht Patricia Luis Jan Degrève Bart Van der Bruggen 《Journal of the American Oil Chemists' Society》2011,88(8):1255-1261
The extraction stage of edible oil in the oil industry is commonly performed by using toxic solvents (e.g. hexane) and processes with high energy consumption (e.g. distillation, evaporation) to recover the solvent, which represents around 70–75 wt% in the oil–solvent mixture. In this paper, a membrane-based extraction method using nanofiltration (NF) membranes is presented. Commercial nanofiltration membranes made of different polymers (Desal-DK-polyamide NF from GE-osmonics®, NF30 polyethersulfone NF from Nadir®, STARMEMTM122 polyimide from MET® and SOLSEP NF030306 silicone base polymer SOLESP®) were selected and tested to recover the solvent from soybean oil/solvent (10–20–30% w/w oil) mixtures at various separation pressures and constant temperature in a dead-end filtration set up. The selection of the solvent was made in order to compare solvents obtainable from renewable resources, such as ethanol, iso-propanol and acetone, with solvents traditionally used in the industry (i.e. cyclohexane and n-hexane). The structural stability of the membranes towards the different solvents used in this work was verified visually, by the variation of the membrane area and by means of permeate flux assessments. Desal-DK and NF30 showed poor filtration performance and even visible defects after exposure to acetone but a good performance was obtained for the nanofiltration membranes STARMEMTM122 and SOLSEP NF030306 with ethanol, iso-propanol and acetone. For example, considering a mixture with 30% edible oil in acetone, STARMEMTM122 shows a flux and oil rejection of 16.8 L m?2 h and 70%, respectively. For the same conditions, SOLSEP NF030306 exhibited a flux of 4.8 L m?2 h with 78% rejection, which shows the potential application of nanofiltration membranes in the oil industry. 相似文献
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The resistance of novel surface crosslinked Chitosan/poly(acrylonitrile) (PAN) composite nanofiltration (NF) membranes to pH and organic solvents was studied with respect to the effects of crosslinking parameters, namely, glutaraldehyde concentration and crosslinking time. The pH resistance was determined by permeation of aqueous acidic (pH 2.5) and basic (pH 11) solutions as well as swelling studies in the pH range of 2.5–11. The solvent resistance was determined by swelling, immersion, and permeation studies with several industrially important organic solvents, namely methanol, ethanol, iso‐propanol, methyl ethyl ketone, ethyl acetate and hexane. It was observed that the crosslinked composite membranes maintain the permeate fluxes for test solvents for 2 h of continuous operation without any significant change in flux. SEM studies on membrane samples after immersion as well as permeation with the above‐mentioned solvents indicated that the membrane morphology was maintained. The results are explained in terms of solvent–membrane polar and hydrophobic interactions, using solubility parameters of membrane and solvents and dielectric constants of solvents. Pure water flux and polyethylene glycol transmission data indicated that at pH 2.5 and 11, the membrane stability increased with increasing glutaraldehyde concentration and was much better at pH 11 than at pH 2.5. All surface crosslinked membranes showed reduced swelling between pH 4–10. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 77: 1782–1793, 2000 相似文献
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Phase separation phenomena of polyetherimide (PEI)/solvent/nonsolvent systems were investigated by measuring their precipitation values over the temperature range from 20 to 50°C. The solvents used are N‐methyl‐2‐pyrrolidone (NMP), dimethylacetamide (DMAC), and dimethylformamide (DMF). Nine nonsolvents were employed including water, methanol, ethanol, 1‐propanol, 2‐propanol, acetic acid, propionic acid, ethylene glycol, and diethylene glycol. Based on the measured precipitation values, critical solubility parameters for PEI were calculated, and the partial solubility boundary for PEI was obtained in a two‐dimensional solubility parameter coordinate graph. The relationship between solvent strength and membrane structure was examined using PEI hollow‐fiber membranes prepared from binary polymer solutions containing NMP, DMAC, and DMF as solvents. Water was used both as internal and external coagulants. The cross‐sectional structure and gas permeation properties of these hollow fibers were examined. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 71: 1789–1796, 1999 相似文献
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The solubility parameter of polyisobutylene has been determined from intrinsic viscosity measurements in a single solvent as a function of temperature. The change in solubility parameter of the solvent as a function of temperature was calculated form the equation \documentclass{article}\pagestyle{empty}\begin{document}$ \frac{{d{\rm}ln \delta s}}{{d{\rm}ln Vs}} = - \frac{{n + 1}}{2} $\end{document} where Vs, the molal volume, changes with temperature. The vlaue for the solubility parameter thus obtained compares well with values reported in the literature for intrinsic viscosity measurements in a series of solvents. Similar measurements were made with an ethylenepropylene copolymer. The solubility parameter of 87 mole % C2 ethylene-propylene copolymer was determined to be 8.1-8.6 in either toluene or methylcyclohexane. 相似文献
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根据浓差极化模型和非平衡热力学模型,对4种纳滤膜(NF40膜、NTR7450膜、Desal5膜和G20膜)在不同浓度(10~500mol/m3)的电解质(NaCl)溶液体系的透过实验数据进行回归计算,求得膜的反射系数和溶质透过系数。根据TeorelMeyerSievers模型从膜的反射系数估算这些纳滤膜的有效电荷密度并对其进行了电解质浓度的经验关联。结果讨论同时证明了TeorelMeyerSievers模型适用于纳滤膜的带电特性评价 相似文献
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The sorption-desorption-resorption-redesorption experiments have been conducted to evaluate the transport behaviour of polyethylene glycol (PEG) based polyurethane/polymethyl methacrylate (PU/PMMA, 50/50) semi interpenetrating polymer network (SIPN) with aromatic probe molecules. Molecular migration depends on the nature of the organic solvent, membrane-solvent interaction, temperature, solubility parameter, molecular volume and free volume available within the polymer matrix. The transport parameters like sorption (S), diffusion (D) and permeation (P) coefficients have been calculated for IPN-aromatic probe molecule systems. Sorption and diffusion results measured at different temperatures viz. 20, 40 and 60 °C are found to follow Fickian mechanism. The liquid concentration profiles in the membranes during sorption and resorption processes have been simulated by solving Fick's diffusion equations and by using numerical method. Equilibrium swelling results have been used to measure the molecular mass between cross links, degree of cross linking and cross link density using Flory-Rehner theory. It is found that the mass uptake values decreased with increase in cross link density during polymer-solvent interactions. The estimated Arrhenius activation energy for diffusion (ED) and permeation (EP) are indicative of nature of liquid and their interaction with membrane. Thermodynamic parameters like change in entropy (ΔS) and enthalpy (ΔH) have been calculated using van't Hoffs equation. The rate of evaporation of liquids have been calculated for desorption and redesorption runs, and these results depend on volatility of solvents. 相似文献
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Pebax membrane for CO2/CH4 separation: Effects of various solvents on morphology and performance
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In this study, the effects of different solvents on the morphology and permeation of poly(ether‐block‐amide) (Pebax‐1657) membranes were investigated. Pebax membranes were fabricated via a solution casting method with five different solvents, that is, N,N‐dimethyl formamide (DMF), N,N‐dimethyl acetamide (DMAc), N‐methyl‐2‐pyrrolidone (NMP), formic acid, and a mixture of ethanol (EtOH) with water (H2O). Cross‐sectional scanning electron microscopy analysis of the membranes was performed to investigate the morphology of the prepared membranes. X‐ray diffraction and Fourier transform infrared analysis were also carried out to characterize the membranes. The interactions of the polymer and various solvents were evaluated with Hansen solubility parameters. Permeation experiments for CO2 and CH4 gases were performed to study the effects of the solvents on the permeation properties of the membranes. The solvent properties, such as the molar volume, boiling point, and solubility parameters, were investigated as were the membranes characteristics, such as the crystallinity, d‐spacing, and fractional free volume. The results obtained from the experiments show that the CO2 permeability for the membranes prepared with different solvents followed this order: NMP > DMF > Formic acid > DMAc > H2O/EtOH mixture. With increasing molar volume, the gas permeability increased for all of the membranes, except for DMAc, which showed a lower permeability because of its highly crystalline structure. DMF showed a higher CO2/CH4 ideal selectivity compared to the other membranes and, consequently, could be introduced as the best solvent from all aspects for the Pebax‐1657 membrane. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017 , 134, 44531. 相似文献
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Summary Pervaporation of ethanol-water mixture was examined on IPN membranes composed of hydrophilic polyurethane(PU) and hydrophobia polystyrene(PS). The IPN membranes showed preferential pervaporation of water over ethanol and revealed high permeation rate. As the content of hydrophobic PS was increased, the permeation rate decreased while the separation factor increased, indicating that the PS domains suppressed the swelling of the PU phase and reduced the plasticizing effect. The average diffusion coefficient, computed from the permeation rate and solubility, was highly dependent on the viscosity and concentration of the permeant in the membrane. 相似文献
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Transport model for mixed solvents in glassy polymer membrane is rare in literature. In our previous work, a new experimental method has been developed and absorption kinetic curves for two mixed solvent systems (ethanol/1,2-dichloroethane and ethanol/ethyl acetate) in polyurethane (PU) membrane at have been measured. In this work, based on Liu et al.'s transport model for single solvent/polymer membrane system, a transport model for the absorption of mixed solvents in glassy polymer membrane is established. Three model parameters in this model can be obtained by correlating the experimental data of the corresponding single solvent/polymer membrane systems; the other three should be determined by correlating the experimental data of mixed solvents/polymer membrane system. The effect of model parameters on diffusion is studied by numerical simulation. The correlated results agree well with the experimental absorption curves. The model has the ability to predict the transport phenomena of mixed solvents in polymer membrane. 相似文献
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Katia Rezzadori Frederico M. Penha Mariane C. Proner Guilherme Zin Jos C. C. Petrus Marco Di Luccio 《化学工程与技术》2019,42(12):2700-2708
Polymeric membranes subjected to the permeation of n‐hexane were characterized and the influence of pretreatment with ethanol on the properties of the membranes was studied to assess membrane performance and stability. The results suggest that the selectivity of the membrane depends not only on the pore size, but also to a great extent on the interaction between solvent and polymer. An increase in membrane roughness and contact angle was observed for all membranes after pretreatment with ethanol and n‐hexane permeation. Moreover, the surface free energy decreased after solvents exposure, indicating an increase in membrane surface hydrophobicity and polymer swelling. The studied membranes show feasibility of use for the recovery of solvents, if suitable process parameters are selected. 相似文献
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Comparative studies on the effects of casting solvent on physico‐chemical and gas transport properties of dense polysulfone membrane used for CO2/CH4 separation
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Jimoh K. Adewole Abdul Latif Ahmad Suzylawati Ismail Choe Peng Leo Abdullah S. Sultan 《应用聚合物科学杂志》2015,132(27)
The effects of casting solvents on the physico–chemical and transport properties of polysulfone membranes were investigated. Comparative analysis of the properties of membranes prepared from a new solvent (diethylene glycol dimethyether, DEG) and other commonly used solvents (1‐methyl‐2‐pyrrolidone, N,N‐dimethylacetamide, dimethyl sulfoxide and N,N‐dimethylformamide) were performed using gas permeation, X‐ray diffraction, scanning electron microscopy, thermogravimetric, and Fourier transform infrared spectroscopy analyses. The degree of polymer–solvent interaction was evaluated using the solvent molar volume, and Hansen and Flory–Huggins parameters. Membrane prepared from DEG displayed a relatively higher permeability of 29.08 barrer and CO2/CH4 selectivity of 23.12 compared to membranes prepared from other solvents. This improved performance was attributed to the better interaction between the DEG solvent and polysulfone than other solvents that were considered. DEG has the highest molar volume of 142.280 cm3/mol and the lowest Flory–Huggins parameter of 0.129. Thus a thorough evaluation of polymer–solvent interaction is very crucial in preparing membranes with optimum performance. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42205. 相似文献
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根据浓差极化模型和非平衡热力学模型,对4种品牌的纳滤膜(NF40膜、NTR7450膜、Desal5膜和G20膜)在醇类和糖类中性溶质体系的透过实验数据进行回归计算,求得膜定数(即膜的反射系数和溶质透过系数),再由这些膜定数结果根据细孔模型估算了4种品牌的纳滤膜的细孔结构参数,这4种膜的细孔半径范围在0.4~0.8nm。结果讨论表明细孔模型适用于纳滤膜的结构评价。 相似文献
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Membrane processing of crude vegetable oils: Pilot plant scale remoyal of solvent from oil miscellas
S. S. Köseoglu J. T. Lawhon E. W. Lusas 《Journal of the American Oil Chemists' Society》1990,67(5):315-322
The recovery of solvents used in the extraction step of edible oil processing is required for economical, environmental, and
safety considerations. The miscella (mixture of extracted oil and solvent) exits the extractor at 70 to 75 wt% solvent content.
Currently, the solvent is recovered by distillation.
This paper reports the results of a study on separation of vegetable oils from commercial extraction solvents using various
types of Reverse Osmosis (RO) and Ultrafiltration (UF) membranes.
Solvent permeation rates and separation performances of various RO and UF membranes were determined by using ethanol, isopropyl
alcohol and hexane as the solvents. One membrane exhibited a flux of 200 GFD (ethanol) with 1% oil remaining in the permeate.
However, hexane rapidly deteriorated all but one of the membranes tested. The membrane that was compatible with hexane had
a low flux and unacceptably low oil retention.
Industrial-scale membranes were also evaluated in pilot plant trials. A hexane separation was attempted with a hollow-fiber
membrane unit, and it was noted that the pores of the fibers swelled almost closed. Some of the commercially available membranes
selectively removed solvent (ethanol or isopropanol) from the edible oil miscellas with reasonable flow rates.
The research reported has shown that membranes manufactured from polyamide were the least affected by hexane. Fluxes achieved
during solvent-oil separations were increased by increases in either temperature or pressure and decreased by increases in
oil concentration in the feed. The processing temperature affected the percentage of oil in solution in either ethanol or
isopropanol as well as the viscosity of the feed. Both of these factors in turn influenced the flux achieved.
Approximately 2 trillion Btu/yr could be saved using a hybrid membrane system to recover solvents used in the extraction step
of crude oil production. Studies to date report marginal success. The development of hexane-resistant membranes may make this
application viable. 相似文献
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D. Hoernschemeyer 《应用聚合物科学杂志》1974,18(1):61-75
The viscosity of concentrated (17.5 g/dl) solutions of cellulose acetate in 11 single solvents and in four binary solvent mixtures was related to a thermodynamic measure of solvent power. In single solvents, the specific viscosity varied from 4600 in dimethyl sulfoxide to 78,000 in diacetone alcohol, with the specific viscosity increasing with decreasing abolute value of the partial molar free energy of dilution. This behavior can be accounted for by the hypothesis that the number of chain entanglements increases with decreasing solvent power. In solvent mixtures, the specific viscosity often attains a minimum value at a composition where the average solubility parameter locus is near the center of the solubility region of the polymer. 相似文献
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Pervaporation (PV) of methanol/water and ethanol/water mixtures through PDMS membrane was investigated using a PV cell (in laboratory scale). PDMS membrane is a well-known hydrophobic membrane for removing organics from aqueous mixtures. Experimental results were obtained at different initial alcohol (methanol and ethanol) concentrations (0.3-3 wt%) and temperatures (30-). Recirculation flow rate was kept constant at a value of 15.6 l/h. Average permeation flux (j), separation factor (α) and activation energy of permeation (EP) were calculated. Separation factor of PDMS membrane for methanol was greater than that for ethanol. Total flux for methanol/water and ethanol/water mixtures was observed to vary from 0.37 to 0.56 and 0.52 to 0.90 at , respectively, as alcohol concentration changed from 0.3 to 3 wt%. Separation of alcohols depends on both their selective sorption in polymeric membrane and their diffusivity. The most important observation was that separation factor of methanol/water mixtures is greater than that of ethanol/water mixtures and it is because of different molecular size of alcohols. Different behavior of alcohol/water mixtures can also be explained in the entire concentration range studied using relative values of solubility parameters of the alcohols. It can be due to the fact that activation energy of alcohol permeation increases as solubility parameter difference between alcohol and membrane increases. 相似文献
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2‐(2‐Aminoexthoxy)ethanol or diglycolamine (DGA) is a CO2 absorption solvent that is suitable to treat natural gas, flue gas, and biogas or landfill gas. Equilibrium CO2 solubility in concentrated aqueous DGA solvents with varying molality was measured under absorption and desorption conditions at different temperatures. Viscosity and surface tension of the solvent before absorption, after absorption, and after desorption were determined. With increasing DGA molality, CO2 loading remained constant until the number of moles of DGA exceeded the number of moles of water. For a given DGA molality, with higher CO2 loading, viscosity increased exponentially and surface tension rose with a power of two. 相似文献
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Bartosz TylkowskiAuthor Vitae Iren TsibranskaAuthor VitaeRuslan KochanovAuthor Vitae Georgi PeevAuthor VitaeMarta GiamberiniAuthor Vitae 《Food and Bioproducts Processing》2011,89(4):307-314
In the present study experimental results on the nanofiltration of ethanolic extracts from Sideritis ssp. L. are reported, regarding polyphenols and flavonoids concentration and solvent reuse. Three membranes, resistant to organic solvents, have been used: Starmem™ 240 (polyimide), Duramem™ 300 and Duramem™ 500 (both of them modified polyimide). The dependence of the membrane rejection on its MWCO is presented. The separation of flavonoids from phenols with lower molecular weight is found possible at MWCO > 400 Da. A decrease of the flux is observed at permeate to feed volume ratio of about 0.58, thus indicating the existence of a critical concentration, independent of the feed volume and MWCO of the membranes used. The membrane behaviour during nanofiltration has been characterised by ESEM and ATR-FTIR.Concentrations of active compounds up to 3-4 times higher have been obtained in the retentates. The extracts concentrated by nanofiltration preserve their high antioxidant activity. Further dilution of the retentates displays a logarithmic concentration dependence of the radical scavenging activity. The experiments have proved the possibility for permeate use for extraction instead of ethanol, thus essentially reducing the volume of the solvent. 相似文献