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1.
《分离科学与技术》2012,47(8):1884-1893
Abstract

In this study, a preparative high performance centrifugal partition chromatography (HPCPC) method for isolation and purification of the bioactive component piperine directly from the ethanol extract of Piper nigrum L. was successfully established by using n-hexane-ethyl acetate-methanol-water as the two-phase solvent system. The upper phase of n-hexane-ethyl acetate-methanol-water (6:5:6:5, v/v) was used as the stationary phase of CPC. Under the optimum conditions, 40 mg of piperine at 98.5% purity, as determined by HPLC, was yielded from 300 mg of the crude extract in a single CPC separation. The peak fraction of CPC was identified by 1H NMR and 13C NMR.  相似文献   

2.
Gallic acid and ellagic acid have been identified in the seed of Cornus officinalis by the use of an ultrahigh performance liquid chromatography (UHPLC) method coupled with a diode array detector (DAD). The water extract of C. officinalis seed contained the highest gallic acid content (3.03 ± 0.10 mg/g seed), which was followed by aqueous methanol extract (2.43 ± 0.10 mg/g seed) and aqueous ethanol extract (1.53 ± 0.25 mg/g seed). But a higher concentration (12.32 ± 0.45 mg/g seed) of ellagic acid was obtained from extraction with aqueous methanol than with aqueous ethanol (11.03 ± 0.42 mg/g seed) and water (7.28 ± 0.16 mg/g seed). After heat treatment and acid hydrolysis, C. officinalis seed had higher concentrations of gallic acid and ellagic acid, contributing to more potent antioxidant activity. The results demonstrated a rich source of gallic acid and ellagic acid in C. officinalis seed, which might provide a novel source of these natural antioxidants.  相似文献   

3.
《分离科学与技术》2012,47(5):706-715
Thin film composite (TFC) hydrophobic PDMS membrane of 5 µm active layer thickness supported on Polyethersulfone (PES) ultraporous substrate was synthesized and thermally crosslinked for the pervaporation based extraction of organic solvents such as Tetrahydrofuran (THF) and Ethylenedichloride (EDC) for the first time. The study was extended to acetone, ethanol, t-butanol, Iso-butanol, and acetic acid. Membranes were characterized by SEM, TGA, XRD, and FTIR to study the surface and cross-sectional morphology, thermal stability, crystalline nature, and structural properties, respectively. High selectivities of 868, 72, and 31 were observed at organic feed concentrations of 0.68, 3.42, and 9.38 wt% in water with reasonable fluxes of 0.2, 0.16, and 0.31 kg m?2 h?1 for EDC, THF and acetone, respectively at a downstream vacuum of 0.5 mmHg. The estimated mass transfer coefficients (MTCs) were found to be 9.11 × 10?6, 11.77 × 10?6, and 10.73 × 10?6 m s?1 for THF, EDC, and acetone extraction, respectively. The membrane exhibited considerable feasibility for scale-up due to its composite nature with significant potential for extraction of volatile organic solvents present in low concentrations. A comparison with previous values reported in literature revealed higher selectivities for extraction of EDC, THF and acetone using the present membrane.  相似文献   

4.
The aim of the present study was to use supercritical technology to recover linseed oil (Linum usitatissimum L.) using carbon dioxide (alone or modified with ethanol as solvent) to determine the influence of the technique on the chemical composition of the oil obtained, model the kinetic curves of extraction, and estimate the manufacturing cost of the process. The experiments were conducted at 323 K, pressure of 25 MPa, constant solvent flow of 1.7 × 10?5 kg/s, and extraction time of 5 h. The highest yield was obtained with the addition of cosolvent (28.8%). The SFE process of linseed oil manufacture proved to be economically viable, resulting in a product with a specific cost of 13.21 US$/kgoil. As to oil composition, the main fatty acids detected were linolenic and oleic acid.  相似文献   

5.
《分离科学与技术》2012,47(7):997-1005
The equilibrium study on reactive extraction of picolinic acid by six different extractants (phosphoric and aminic) dissolved in two different diluents (benzene and decane-1-ol) is carried out to evaluate the performance of extractants and diluents. The extraction ability in terms of the distribution coefficient (K D) is found to be in the order of tri-n-octylamine (TOA) ≥ tri-n-dodecylamine (TDDA) > di-2-ehylhexyl phosphoric acid (D2EHPA) > tri-n-butyl phosphate (TBP) > tri-octyl methyl ammonium chloride (Aliquat 336) > tri-n-octyl phosphine oxide (TOPO) with both diluents. Decan-1-ol is found to be the better solvating medium for the acid-extractant complexes. A mathematical model based on mass action law is employed to estimate the values of partition coefficient (P) and dimerization constant (D) in physical extraction, and equilibrium extraction constants (K E) in chemical extraction. The values of loading ratios (Z) less than 0.5 imply the formation of (1:1) acid:extractant solvates in the organic phase. Decan-1-ol with TOA is the most effective solvation medium with K D, max = 9 at 0.01 kmol · m?3 of picolinic acid and K E = 19.448 m3 · kmol?1.  相似文献   

6.
《分离科学与技术》2012,47(8):1272-1279
Dewaxed Calamagrostis angustifolia Kom was pretreated with hot water at 60 and 90°C for 3 h, and then the residue obtained was successively treated with 70% ethanol, and 70% ethanol containing 0.2%, 1.0%, 2.0%, 4.0%, and 8.0% NaOH at 80°C for 3 h. The dissolved components were subjected to further separation to get eight lignin fractions, which were characterized by gel permeation chromatography, Fourier transform infrared, and sugar analysis. All the lignin fractions had small weight-average molecular weights between 810 and 2580 g/mol. Two typical lignins, L3 (prepared with 70% ethanol) and L5 (prepared with 70% ethanol containing 1.0% NaOH), were further analyzed using 1H, 13C NMR and HSQC spectroscopy. Signals from guaiacyl (G), syringyl (S), and p-hydroxyphenyl (H) units observed in aromatic/olefinic region of HSQC spectra indicated that the lignin from Calamagrostis angustifolia Kom could be classified as “GSH” lignin. In aliphatic-oxygenated region, β-O-4′ together with small amounts of β-5′, β-β′, and p-hydroxycinnamyl alcohol end group were the main interunit linkages observed. Aqueous ethanol, which could avoid the cleavage of ether bonds in lignin at neutral condition, was more effective than water on lignin extraction.  相似文献   

7.
《分离科学与技术》2012,47(17):2695-2703
ABSTRACT

Peanut skin is a waste by-product from peanut industries. It is rich in antioxidants and bioactive compounds. Therefore, the objective of this study was to empirically model and optimize supercritical CO2 extraction of oil from peanut skin. The extraction conditions were pressure (100, 200 and 300 bar), temperature (313, 328 and 343 K) and rate of modifier ethanol (0.075, 0.15 and 0.225 mL/min). The extraction process was subsequently examined using modified Brunner and Esquivel models. The optimum conditions for extraction peanut skin oil were 279 bar, 70°C and rate of modifier of 7.5% with a maximum yield of peanut skin oil of 0.83 g and initial slope of 0.568 g/min.  相似文献   

8.
《分离科学与技术》2012,47(14):3637-3651
Abstract

The influences of extraction solvents and techniques on the yield of alkaloids from the embryo of the seed of Nelumbo nucifera GAERTN, were comprehensively investigated in this work. After the preliminary tests (extraction solvents and extraction methods), several parameters, such as ethanol concentration, extraction time, the ratio of liquid to solid were optimized using an experimental design, response surface methodology, and accelerated random search algorithm (ARSA). The results showed the best experimental conditions for total alkaloids (T.A). Using ultrasound-assisted extraction were ethanol concentration: 75%, extraction time: 20 min, and the ratio of liquid to solid: 30:1.  相似文献   

9.
《分离科学与技术》2012,47(5):1091-1110
Abstract

High pressure liquid extraction (HPE) and subcritical fluid (CO2+ethanol) extraction (SCE) were used for the extraction of total phenolic compounds (TPC) from sour cherry pomace. Antiradical efficiency (AE) of the extracts was also determined. Ethanol was the solvent for HPE and co‐solvent for SCE. Combinations of pressure (50, 125, 200 MPa), temperature (20, 40, 60°C), solid/solvent ratio (0.05, 0.15, 0.25 g/ml) and extraction time (10, 25, 40 min) were variables for HPE according to the Box‐Behnken experimental design. The variables used for SCE were pressure (20, 40, 60 MPa), temperature (40, 50, 60°C), ethanol concentration (14, 17, 20 wt%) and extraction time (10, 25, 40 min). For HPE, TPC, and AE at the optimum conditions (176–193 MPa, 60°C, 0.06–0.07 g solid/ml solvent, 25 min) were found as 3.80 mg gae/g sample and 22 mg DPPH?/g sample, respectively. TPC and AE at the optimum conditions (54.8–59 MPa, 50.6–54.4°C, 20 wt% ethanol, 40 min) for SCE were determined as 0.60 mg gae/g sample and 2.30 mg DPPH?/g sample for sour cherry pomace, respectively.  相似文献   

10.
Removal of perfluorinated alkylated substances (PFAS) such as perfluorooctanoic acid (PFOA) from aqueous solution is an actual topic in light of their widespread diffusion and their persistence in the environment. The process of adsorption has been identified as an effective technique to eliminate PFAS in water, however the process efficiency strongly depends on the adsorbents employed (silica, alumina, activated carbon, layer doubled hydroxides). In this work three nanostructured mesoporous silica materials of similar pore diameter (~4 nm) featuring high surface area (~900 m2/g) and high pore volume (0.7–1.0 mL/g) were evaluated in PFOA removal: calcined MCM-41 (MCM-41c), calcined hexagonal mesoporous silica (HMSc) and HMSe obtained after ethanol extraction of the amine templates from HMS. Sorption kinetics and isotherms were performed at PFOA concentrations from 10 µg/L to 10 mg/L. It appeared that HMSe showed much faster and higher adsorption capacity for PFOA than the other tested adsorbents (MCM-41c and HMSc) whatever the pH of the solution (5 < pH < 9). Thermogravimetric analysis of HMSe evidenced that the ethanol extraction of the templating amines was not complete (70 %) and HMSe possessed some remaining hexadecylamine (HDA) (0.08 mol amine per mol SiO2) on the surface conferring some hydrophobic properties to the adsorbent and also some probable complex formation between anionic PFOA? and protonated HDA. Indeed, the incomplete amine extraction is surely due to the presence of protonated HDA in strong electrostatic interactions with SiO? avoiding their removal by simple ethanol extraction as for H-bonding amine with Si–OH groups. Considering both adsorption isotherms and adsorption kinetics, PFOA could be efficiently removed from contaminated water in a wide range of concentration by an environmental friendly adsorbent as HMSe.  相似文献   

11.
ABSTRACT

A selective and sensitive solvent extraction and spectrophotometric study of the ruthenium(III)–p-methylphenyl thiourea (PMPT) system is presented. The optimum conditions were determined by a critical study of acid concentration, reagent concentration, equilibration period, heating time and effect of solvent on the equilibrium. Ruthenium(III) forms 1:1 complex with PMPT in 20% ethanol and extracted into chloroform. Conformity to Beer’s law at 600 nm was observed up to 40 µg mL–1 of ruthenium. Molar absorptivity and Sandell’s sensitivity were found to be 2.31 × 103 L mol?1cm?1 and 0.044 μg cm?2, respectively. The detection limits were 0.11 μg mL?1 of ruthenium. The method is free from interferences from large number of cations and anions. Proposed method was successfully applied to the separation and determination of ruthenium from synthetic alloys, catalyst and water samples. Sequential separation and determination method for ruthenium(III), osmium(VIII) and iron(II) has been developed.  相似文献   

12.
《分离科学与技术》2012,47(4):652-658
This work describes an optimized supercritical fluid extraction (SFE) process of osthole and imperatorin from the fruits of Cnidium monnieri (L.) Cusson. Response surface methodology (RSM) was employed to evaluate the effects of independent variables on the yields of osthole and imperatorin. The independent variables were extraction pressure (100 to 300 bar), temperature (50 to 70°C), and ethanol flow rate (0 to 0.4 mL/min). Results indicated that the data could be well fitted to two second-order polynomial models in the selected experimental domain. The effects of independent variables of pressure, temperature, ethanol rate flow, as well as the interactions between pressure and ethanol flow rate, and between temperature and ethanol flow rate on the extraction yield were significant for osthole or imperatorin extraction (p < 0.05). The models predicted that the optimized conditions were 243 bar, 64°C, ethanol flow rate of 0.28 mL/min, giving maximum yields of 1.29% and 0.53% for osthole and imperatorin, respectively, that were in good agreement with the experimental values. The extraction yields obtained with the optimized SFE and Soxhlet extraction were compared.  相似文献   

13.
ABSTRACT

During the extraction of lithium from high Mg-containing salt lake brines by tributyl phosphate (TBP) in the presence of Fe(III), H+ is used to stabilize Fe(III). However, the distribution ratio of H+ (DH) is 4–6 times higher than that of Li+ (DLi), which affects the extraction of Li+ significantly. In this study, the competition mechanism between H+ and Li+ was investigated by spectral analysis and thermodynamic equilibrium. The extracted species are determined as HFeCl4 · 2TBP and LiFeCl4 · 2TBP for H+ and Li+, respectively. The apparent equilibrium constants are KH = 799.8 and KLi = 120.6, respectively. Both equilibrium constants and the distribution ratios for H+ and Li+ extraction show that extraction of H+ is stronger than Li+.  相似文献   

14.
《分离科学与技术》2012,47(12):2527-2537
Abstract

The possibility of using Dibenzoylmethane (DBM) for uranium(VI) concentrating by the way of micellar extraction at cloud point temperature and later spectrophotometric determination was investigated. Under the optimum conditions, preconcentration of 50 mL of water samples in the presence of 0.2% (w/v) octylphenoxypolyethoxy ethanol (Triton X‐114), 2×10?4 mol L?1 DBM and 2×10?3 mol L?1 buffer solution (pH=9) gave a limit of detection 11 ng mL?1, and the calibration graph was linear in the range of 15–300 ng mL?1. The recovery under optimum working conditions was higher than 98%.

The proposed method has been applied to the spectrophotometric determination of uranium(VI) in natural water samples after cloud point extraction with satisfactory results.  相似文献   

15.
《分离科学与技术》2012,47(8):1784-1798
Abstract

Distribution of formic acid (methanoic acid) between water and tri octyl amine (TOA) dissolved in various alcohols (isoamyl alcohol, hexan-1-ol, octan-1-ol, nonan-1-ol, decan-1-ol) as diluents, as well as the extraction capacity of pure diluent alone have been studied at isothermal conditions. All measurements were carried out at 298.15 K. The difference between the physical extraction and reactive extraction was studied. The loading factor, T T, extraction efficiency, D E, modified separation factor, S F, and, distribution coefficients, K D were calculated. The isoamylalcohol was found most effective solvent with maximum distribution value of 14.521. Possible equilibrium complexation constants for (acid:amine) (5:1), (6:1), and (7:1) have been determined as values of about 21.8 × 103, 15.6 × 104, and 11.1 × 105 for K51, K61, and K71, respectively with isoamylalcohol. Furthermore, Linear Solvation Energy Relationship (LSER) model equation has been obtained to calculate distribution coefficients for alcohols with regression coefficient of 0.981.  相似文献   

16.
This study investigates the evaporation of sessile drop comprising ethanol and water mixture on horizontal poly methyl methacrylate surface. The contact angle (θ) and contact radius (R) of ethanol-water mixture drop are recorded with time, considering the impacts of presence of ethanol. With excess ethanol, the drop evaporation is principally controlled by a phase in which both the contact angle and contact radius are falling. A diffusional model assuming linear relation between contact radius and time is proposed as θ = eR ?3 + cR ?1, where e and c denote fitting coefficients. This model correlates with the experimental data.  相似文献   

17.
《分离科学与技术》2012,47(3):671-681
Abstract

Response surface methodology (RSM) was applied to predict optimum conditions for microwave‐assisted extraction (MAE) of flavonoid from Radix Astragali. A central composite design was used to monitor the effect of temperature, extraction time, solvent‐to‐material ratio, and the ethanol concentration on yield of total flavanoid (TFA). Optimum extraction conditions were predicted as 108.2°C, 26.7 min, 23.1 ml/g solvent‐to‐material ratio and 86.2% ethanol. The maximum yield 1.234±0.031 mg/g was close to the yield of Soxhlet and higher than that of ultrasound assisted extraction and heat reflux extraction. MAE was an effective alternative to conventional extraction methods.  相似文献   

18.
《分离科学与技术》2012,47(16):2738-2748
ABSTRACT

The present study is aimed to optimized diluent type, tri-n-butyl phosphate (TBP) composition and temperature for the reactive extraction of p-nitro phenol (PNP) in two different PNP concentration ranges [(0.00036–0.00646) kmol·m?3 and (0.00646–0.01437) kmol·m?3] as found in industrial effluents. 1-Octanol is investigated as the best diluent with TBP based on COSMO-RS theory. Equilibrium study based on mass action law is performed to find the insights of extraction mechanisms, equilibrium constant (K = 295.12 k·mol?1) and stoichiometry (m:n = 1:1) as also confirmed by FTIR. Thermodynamic parameters, enthalpy (ΔH°), and entropy (ΔS°) are determined 27.51 K J mol?1 and ?50.21 J mol?1 K?1, respectively.  相似文献   

19.
《分离科学与技术》2012,47(5):720-726
This article presents results on the liquid-liquid extraction studies for the separation of tannic acid from aqueous and hydro-alcoholic medium. These liquid-liquid extraction studies aim to investigate the suitable hydrophobic solvent or solvents combination and to optimize the extraction conditions for the quantitative separation of tannic acid from aqueous and hydro-alcoholic feed. A mixture of hexanol and octanol is found to be most suitable for the quantitative extraction of tannic acid from aqueous feed solution. One hour equilibration time was enough to reach equilibrium. With increase in tannic acid concentration from 10 mg · L?1 to 900 mg · L?1 in the feed solution, the extraction of tannic acid was found to be decreasing. The concentration of ethanol plays an important role in controlling the solubility of feed in hydrophobic solvent. The suitable solvent combination was tested for the selectivity for individual polyphenol from a mixture of tannic acid and Epi-catechin and it was found that a combination of hexanol and octanol was good for tannic acid extraction whereas decanol was more selective for Epi-catechin extraction.  相似文献   

20.
《分离科学与技术》2012,47(11):1657-1664
Statistical experimentical designs were applied to optimize microwave-assisted extraction of puerarin from Radix Puerariae. The most important factors affecting the extraction procedure were determined using a Plackett-Burman design. Results indicated that the concentration of ethanol, solvent-material ratio, extraction time, and microwave power were the main factors affecting the extraction yield. These factors were further optimized using a central composite design and response surface methodology. The optimal extraction parameters were ethanol concentration of 52.36%, microwave irradiation time of 60 s, microwave power of 184.8 W and solvent-material ratio of 25:1(mL/g). The average experimental puerarin yield under the optimum conditions was found to be 11.97 mg/g, which agreed with the predicted value of 11.8 mg/g. The proposed method shows high degree of reproducibility.  相似文献   

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