Recovery of Furfural from Aqueous Solution by Ionic Liquid Based Liquid–Liquid Extraction

Abstract

Liquid–liquid extraction with imidazolium based ionic liquids ([C₄mim][PF₆], [C₆mim][PF₆], and [C₈mim][PF₆]) is proposed for the separation of furfural or 5-methylfurfural from aqueous solution. Factors affecting the extraction of furfural or 5-methylfurfural have been studied. It was shown that the extraction equilibria can be achieved within 30 min and the process was less affected by the factors such as volume ratio and feed concentration. The partition coefficients of furfural and 5-methylfurfural decreased with increasing temperature. [C₆mim][PF₆] was found to have the best extraction ability among the three ionic liquids studied. Presence of small amount of NaCl or Na₂SO₄ in the aqueous phase results in the considerable increase in the partition coefficients of furfural because of the competitive hydration of the salts with furfural. A thermodynamic study revealed that the extraction process was driven mainly by hydrophobic interactions. Further experimental results indicated that furfural can be separated selectively from aqueous furfural/acetic acid mixtures.     

Simultaneous effect of temperature and pressure on catalytic hydrothermal gasification of glucose

Gasification of glucose in near- and supercritical water was investigated at temperature and pressure ranges from 400 to 600 °C and 20 to 42.5 MPa with a reaction time of 1 h. Hydrothermal gasification of glucose was performed in the absence and presence of catalyst (K₂CO₃) in a batch reactor. The influences of temperature and pressure in the supercritical regimes of water, catalyst were examined in relation to the yield and composition of the gases and aqueous products. The product gases were analyzed by gas chromatography, and the aqueous products were analyzed by high performance liquid chromatography. The gases produced were carbon dioxide, methane, hydrogen, carbon monoxide, and C₂–C₄ hydrocarbons and there was significant production of aqueous products and residue. The aqueous products composed of oxygenated compounds, including carboxylic acids (glycolic acid, formic acid, acetic acid), furfurals (furfural, 5-hydroxymethyl furfural, 5-methyl furfural), phenols (phenol, methyl phenols, hydroxy phenols, methoxy phenols), aldehydes (formaldehyde, acetaldehyde, acetone, propionaldehyde), ketones (3-methyl-2-cyclo-pentene-1-one, 2-cyclo-pentene-1-one) and their alkylated derivatives. Carbon gasification efficiencies were improved by addition of K₂CO₃ into the reacting system. Carbon gasification efficiency reached maximum (94%) at 600 °C and 20 MPa. The yield of hydrogen among gaseous products increased with increasing temperature and decreasing pressure.     

糠醛生产工艺研究综述

对国内外糠醛生产工艺的研究进行了综述。催化剂的改进以改良硫酸法、无机盐法或固体酸催化剂为研究方向。生产工艺由一步法向二步法转化,由有机溶剂或临界CO2萃取糠醛替代水蒸汽汽提。通过采用络合萃取、相转移法、膜蒸馏处理技术或粉末活性炭处理工艺等对废水进行处理,回收废水中的有用组分如醋酸等,使废水实现零排放。糠醛渣以用作复合肥料、或用作制取葡萄糖或燃料乙醇的原料或用于制取活性炭等研究方向为主。     

Supercritical Carbon Dioxide for the Removal of Hydrocarbons from Contaminated Soil

Abstract

Soil material contaminated with hydrocarbons can be cleaned by supercritical water extraction. Due to the high critical data of supercritical water (Tc = 647 K, P _c = 22.1 MPa), supercritical carbon dioxide (T _c = 304 K, P _c = 7.3 MPa) was investigated as an alternative solvent. The amount of hydrocarbons removed from weathered contaminated soil material with supercritical carbon dioxide was less than 21%.     

SEPARATION PROCESSES FOR RECOVERING ALLOY STEELS FROM GRINDING SLUDGE: SUPERCRITICAL CARBON DIOXIDE EXTRACTION AND AQUEOUS CLEANING

ABSTRACT

Two separation processes have been developed to remove contaminants (cutting oil with trace phosphorus additive) from high-speed steel grinding sludge. One process uses an aqueous surfactant washing technique, and the second process uses supercritical carbon dioxide (SCCO₂) extraction. Our bench-scale aqueous washings have shown that the required phosphorus removal is easily obtained, but a sufficient oil removal is more difficult. The experimental results also indicate a strong dependence of the aqueous washing efficiency on the choice of a suitable surfactant. A mass transfer model is used to simulate a semi-continuous washing process. SCCO₂ extraction at 80 °C and 340 atm shows that approximately 80% of the oil can be removed from the sludge during a 60-minute process to produce a batch of recyclable steel, and that the phosphorus removal also reaches the required level. A linear desorption model is used to describe the irreversible desorption of oil from the solid phase into the CO₂ phase, and the simulated results agree very well with the experimental data.     

Separation of Alkanes and Aromatics with Supercritical Carbon Dioxide

Abstract

The separation of alkanes and aromatics with supercritical carbon dioxide has been studied by measuring vapour-liquid equilibria and selectivities in the model systems 2-methylnaphthalene/hexadecane/ carbon dioxide and 2-methylnaphthalene/dodecane/carbon dioxide. The results have been modelled with the Peng-Robinson equation of state. In both model systems supercritical carbon dioxide appeared selective for the component with the highest vapour pressure, 2-methylnaphthalene respectively dodecane. Consequently alkanes and aromatics will be separated by supercritical carbon dioxide on basis of their difference in vapour pressure instead of their difference in chemical structure.     

Dehydration of Acetic Acid-Water Mixtures with Near Critical and Supercritical Fluid Solvents

Abstract

Equilibrium tie lines and phase densities are presented for acetic acid-water mixtures with near critical propane at 36IK and 52 bar. Experimental measurements were obtained with a static technique; the equilibrium phases were directly sampled with high-pressure liquid sample injection valves at the temperature and pressure of interest. The data obtained in this work indicate that near critical propane can be used to facilitate the production of glacial acetic acid from dilute acetic acid-water solutions. Both these experimental data and our earlier results for acetic acid-water mixtures with supercritical carbon dioxide have been used to test an equation of state which has recently been developed by Grenzheuser and Gmehling for systems which contain associating fluids. Results indicate that the equation's pure component parameters need to be refitted to represent the critical region more accurately.     

Extraction Processes for Bioproduct Separation

Abstract

The three-phase extraction process, a modification of reactive extraction, has been investigated for its applicability in the separation of organic acids from fermentation broth. It has been compared with reactive extraction, liquid membrane permeation, and supercritical fluid extraction.

These processes are based on the use of amine extractants, which have to be dissolved in nonpolar solvents, for the extraction of carboxylic acids, hydroxycarboxylic acids, and aminocarboxylic acids.

This paper considers the comparison of the above-mentioned processes. Furthermore, the extractability of acids from synthetic aqueous solutions and fermented broths has been compared. Principal consideration has been paid to the extraction of lactic acid, gluconic acid, citric acid, and L-leucine.     

Extraction of Fatty Acids from <Emphasis Type="Italic">Boletus edulis</Emphasis> by Subcritical and Supercritical Carbon Dioxide

Mushrooms contain many valuable compounds such as fatty acids, carbohydrates, lycopene, lovastatin, trace elements etc. As they are currently valued for biologically active substances, and as high pressure carbon dioxide fluid extraction has been documented as an effective method for preparing bioactive products from plant materials, subcritical and supercritical carbon dioxide extraction of Boletus edulis mushroom was performed. In the extracts obtained, the fatty acids were determined. Response surface methodology (RSM) was applied to investigate the effect of pressure and extraction time on the extraction yield. The analysis of variance showed that pressure and extraction time had a significant effect on the extraction yield in both investigated process. The interaction between pressure and extraction time had a significant effect only in supercritical extraction process of B. edulis. Higher extraction yields have been obtained by subcritical carbon dioxide, and higher linoleic acid content has been determined in extracts obtained by supercritical carbon dioxide.     

Dependence of Camomile Flower Solubility on Carbon Dioxide Density at Supercritical Extraction

Abstract

The solubility of camomile flowers in supercritical carbon dioxide as it depends on pressure (80–160 bar) and temperature (313–353 K) changes has been determined by using a dynamic procedure. The solubilities obtained were correlated with the density of carbon dioxide by using Chrastil's equation. This equation allows the calculation of the solubility of a complex system.     

The Effect of Pressure and Temperature on Supercritical CO2 Dyeing of PET-Dyeing with Mixtures of Dyes

Abstract

Dyeing is supercritical CO2 is one of the most advanced dyeing technologies. The dyeing medium is not water but carbon dioxide in the supercritical state (temperatures above 31°C and pressures above 74 bar).

The effect of pressure and temperature on dyeing of PET in supercritical CO₂ with only one dye and with mixtures of two or three dyes has been investigated.

The variations of pressure (250 in 300 bar) and temperature (70 in 130°C) cause differences in colour, especially when mixtures of dyes are used. The dyed samples were evaluated using colorimetry and the extraction of dyes from the fabric.

The amount of all dyes on the fabric rises with the rising temperature due to the accelerated motion of molecular chains and the formation of the free volume in the fibre, so important for the diffusion of dyes. The change of pressure does not after the amount of fixed dyes significantly, but the ratio between the dyes is changed when dyeing with mixtures of dyes.     

Hemicellulose Removal from Hardwood Chips in the Pre-Hydrolysis Step of the Kraft-Based Dissolving Pulp Production Process

Abstract

A pre-hydrolysis step to remove hemicelluloses from mixed hardwood chips consisting of maple, aspen, and birch with a ratio of 7:2:1 has been carried out. The effects of parameters on the pre-hydrolysis such as time, temperature, acetic acid addition, and raw material species, were determined. Different sugars, acetic acid, and furfural formation in the pre-hydrolysis liquor were quantified. The results showed that the pre-hydrolysis is a dynamic process, in which the removal of hemicelluloses increased with time while the conversion of extracted hemicelluloses to monosaccharides due to acid hydrolysis increased and part of the xylose was converted to furfural. The maximum temperature was the most critical parameter for hemicelluloses extraction and conversion, and a temperature of 170°C was the optimum for hemicelluloses extraction with relatively low conversion of xylose to furfural. About 11% of the xylan (in both monomeric and oligomeric forms) was removed at 170°C. Due to the presence of a high amount of xylan, birch produced the highest amount of xylose, followed by maple, and then aspen.     

Behavior of (–)-α-Bisabolol and (–)-α-Bisabololoxides A and B in Camomile Flower Extraction with Supercritical Carbon Dioxide

Abstract

A systematic study of the extraction behavior of selected components of camomile flowers in extraction with supercritical carbon dioxide was carried out. (–)-α-Bisabolol and its A and B oxides, which have a wide importance in pharmacology and standardization of camomile flower products, were selected. The dependence of the yield of selected components on the pressure and/or temperature of supercritical extraction was investigated. The results obtained were correlated.     

Reactive extraction of succinic acid using supercritical carbon dioxide

Reactive extraction using supercritical carbon dioxide (scCO₂) and tri-n-octylamine (TOA) was evaluated as a separation method of succinic acid from an aqueous solution. The reactive extraction of succinic acid was performed at varying initial acid concentrations in aqueous solution (0.07–0.45 mol?dm^?3), temperature (35–65°C) and pressure (8–16 MPa). The succinic acid separation was conducted in both batch mode and semi-continuous mode. The highest reactive extraction efficiency of approx. 62% was obtained for the process conducted in semi-continuous mode at 35°C and 16 MPa for the initial acid concentrations in aqueous phase of 0.39 mol?dm^?3.     

Extraction of pomegranate seed oil using subcritical propane and supercritical carbon dioxide

Extraction of oil from pomegranate seeds as a waste product of the juice industry using supercritical carbon dioxide and subcritical propane was studied in this work. The influence of the main operating conditions of extraction, namely, the temperature and pressure of extraction on the oil extraction yield and the correspondent fatty acid profile were analyzed and reported here. Soxhlet extraction with n-hexane was done for comparison with supercritical extraction resulting in a maximum yield of oil of 22.31 wt %. Supercritical carbon dioxide and subcritical propane extracted up to 58.53% (corresponding to maximum yield of 13.06 wt %) and 76.73% (corresponding to maximum yield of 17.12 wt %) of the total amount of pomegranate seed oil as measured using Soxhlet extraction, respectively. Results indicated that the subcritical propane is a suitable and selective solvent for the extraction of the pomegranate seed oil in function of smaller times and pressures employed compared to carbon dioxide extraction. The fatty acid composition of the extracted oil showed the presence of fatty acids of C₁₆, C₁₈, C₂₀, C₂₂, and C₂₄ carbon chains. Punicic (C_18.3) was the major fatty acids and comprise up to 70% of the total fatty acid content of the extracted oil among all samples. Finally, Lack??s plug flow model as developed by Sovova was applied to both extraction systems and a good agreement with the experimental results was obtained.     

Extraction of Nitraria tangutorum seed lipid using different extraction methods and analysis of its fatty acids by HPLC fluorescence detection and on‐line MS identification

The seed lipid of Nitraria tangutorum was extracted by supercritical carbon dioxide extraction, microwave‐assisted reflux extraction, ultrasound‐assisted extraction, or solvent reflux extraction. The experimental parameters of supercritical carbon dioxide extraction including pressure, temperature, particle size, and extraction time were investigated. A facile and sensitive method for the simultaneous determination of 30 saturated and 9 unsaturated fatty acids by HPLC with fluorescence detection after pre‐column derivatization was developed. Fatty acid derivatives were separated on a reversed‐phase Eclipse XDB‐C₈ column in conjunction with gradient elution. Identification of fatty acid derivatives was carried out by on‐line APCI/MS in positive‐ion mode. Excellent quantitative linear responses of the 39 fatty acids were observed in the range of 0.014 to 14 μmol/L with correlation coefficients higher than 0.9992. Limits of detection were in the range of 0.32–3.7 nmol/L (S/N = 3). The fatty acids in Nitraria tangutorum seed lipid with or without saponification extracted by the four different methods were determined and compared. The results indicated that the mass percentage of unsaturated fatty acids (mainly oleic acid, linoleic acid and linolenic acid) in Nitraria tangutorum seed lipid was up to 79%, and the best method was supercritical carbon dioxide extraction.     

Mass transfer from single bubbles in Newtonian liquids

The constant volume technique developed by Calderbank has been used for measuring the instantaneous mass transfer rates for single carbon dioxide bubbles with 0·46<d₀<0·85 cm in n-propanol, i-butanol, acetic acid, distilled water and n-octanol aqueous solution.The decay of mass transfer coefficient with bubble age was observed even in clean pure liquids, and the degree of the decay was high for the system of small bubble and the liquid where the solubility and the diffusivity of carbon dioxide were large. An empirical equation for mass transfer coefficient has been proposed taking the effect of bubble age into account.     

A REVIEW OF THE INDUSTRIAL AND RECENT POTENTIAL APPLICATIONS OF TRIOCTYLPHOSPHINE OXIDE

ABSTRACT

The industrial applications of trioctylphosphine oxide, more commonly known as TOPO, make use of its complexing powers with metals and with hydrogen donor organic compounds. Commercial uses as a solvent extraction reagent are in the recovery of uranium from wet process phosphoric acid and in the recovery of byproduct acetic acid and furfural generated during sulphite wood pulping. Recently investigated potential uses include the separation of niobium from tantalum and the extraction of organic compounds, such as citric acid, from fermentation broths. Each process is discussed briefly.     

The Synthesis and Decomposition of Novel Organophosphorus Complexants

Abstract

Aqueous soluble organic diphosphonic acids have been synthesized as aids in the extraction/recovery of metal values from nuclear waste, ground water, or hydrometallurgical processes. The reagents form aqueous soluble complexes at very low pH values (< 1). After use, these compounds do not represent an additional waste management problem as they are readily decomposed to innocuous materials (phosphoric acid and carbon dioxide) by warming and/or by the action of a mild oxidizing agent.