Kinetic study on reactive extraction of phenylalanine enantiomers with BINAP-copper complexes

Enantioselective liquid–liquid extraction has attracted considerable attention for its potential use in large-scale production. Kinetic data are needed for the reliable scale-up of the process. This paper reports the kinetic study of reactive extraction of phenylalanine (Phe) enantiomers with BINAP–copper complex (BINAP–Cu) as a chiral selector. The theory of extraction accompanied by a chemical reaction was applied. The effects of agitation speed, interfacial area, pH value of aqueous phase, initial concentration of Phe enan-tiomers and initial concentration of BINAP–Cu on the specific rate of extraction were investigated. The for-ward rate constants of the reactions in the reactive extraction process are 7.93 × 10?5 m5/2·mol?1/2·s?1 for D-Phe and 1.29 × 10?4 m5/2·mol?1/2·s?1 for L-Phe.     

Kinetics and the difference for extraction of praseodymium and neodymium from nitrate aqueous solution by[A336] [NO3] using the single drop technique

The kinetics and the difference for Pr(Ⅲ) and Nd(Ⅲ) extraction from nitrate aqueous solution using trialkylmethylammonium nitrate([A336][NO_3]) as extractant were investigated by the single drop technique.The dependence of the extraction rate of Pr(Ⅲ) and Nd(Ⅲ) on the concentrations of free Pr(Ⅲ) and Nd(Ⅲ)ions, the concentrations of Na NO_3 and H~+in aqueous solutions, and the concentrations of [A336][NO_3] in kerosene solutions were discussed and the corresponding extraction rate equations for Pr(Ⅲ) and Nd(Ⅲ) were obtained. These equations demonstrated that the reaction rate constant of Pr(Ⅲ) with [A336][NO_3] was double than that of Nd(Ⅲ). The effect of the addition of diethylenetriaminepentaacetic acid(DTPA) on the difference in the extraction rate of Pr(Ⅲ) and Nd(Ⅲ) by [A336][NO_3] was also investigated. It was revealed that the difference in the complex formation rates of Pr(Ⅲ) and Nd(Ⅲ) with DTPA made a significant impact on the difference in the extraction rates of Pr(Ⅲ) and Nd(Ⅲ) with [A336][NO_3]. The ratio of extraction rates of Pr(Ⅲ) to Nd(Ⅲ) with[A336][NO_3] was in proportion to the ratio of complex formation rates of Pr(Ⅲ) to Nd(Ⅲ) with DTPA. The extraction rate difference for Pr(Ⅲ) and Nd(Ⅲ) with [A336][NO_3] increased due to a higher complex formation rate constant of DTPA with the free and un-complexed Nd(Ⅲ) ions in the aqueous nitrate solution than that with Pr(Ⅲ) ions. Therefore, the addition of DTPA in the aqueous nitrate solution is an effective method to intensify the separation of Pr(Ⅲ) and Nd(Ⅲ) in kinetics. The study on the extraction mechanism indicated that both the extraction of Pr(Ⅲ) and Nd(Ⅲ) by [A336][NO_3] were diffusion controlled, and the reactions obeyed SN2 mechanism. The present work highlights a possible approach to strengthen the kinetic separation of Pr(Ⅲ) and Nd(Ⅲ).     

Reactive extraction for synthesizing long chain ester butyl hexanoate intensified by deep eutectic solvent

Butyl hexanoate(BuHE) is an important long-chain ester that is widely used in the food, beverage and cosmetic industries. In this work, reactive extraction concept was proposed to intensify the BuHE formation in a biphasic system, in which deep eutectic solvent(DES) comprising 2-methylimidazole(2-MIm)and p-toluenesulfonic acid(PTSA) was used as dual solvent-catalyst. First, the effect of 2-MIm to PTSA molar ratio on esterification was investigated to determine the optimum DES of [2-MIm:2 PTSA], which was characterized by FT-IR and TGA. Then, the liquid–liquid equilibrium(LLE) and esterification experiments were carried out to confirm the extraction and catalytic effect of [2-MIm:2 PTSA], respectively.Afterwards, the pseudo-homogeneous kinetic model was employed to describe the esterification kinetics.Finally, the intensification mechanism of reactive extraction for BuHE formation was proposed according to the experiments and interaction effect analysis.     

超临界流体中反应速率常数与密度的相互关系

A new method,which correlates rate constants of chemical reactions and density or pressure in supercritical fluids,was developed.Based on the transition state theory and thermodynamic principles, the rate constant can be reasonably correlated with the density of the supercritical fluid,and a correlation equation was obtained. Coupled with the equation of state (EOS) of a supercritical solvent,the effect of pressure on reaction rate constant could be represented.Two typical systems were used to test this method.The result indicates that this method is suitable for dilute supercritical fluid solutions.     

Solubility prediction of disperse dyes in supercritical carbon dioxide and ethanol as co-solvent using neural network

Nowadays artificial neural networks(ANNs) with strong ability have been applied widely for prediction of nonlinear phenomenon. In this work an optimized ANN with 7 inputs that consist of temperature, pressure, critical temperature, critical pressure, density, molecular weight and acentric factor has been used for solubility prediction of three disperse dyes in supercritical carbon dioxide(SC-CO2) and ethanol as co-solvent. It was shown how a multi-layer perceptron network can be trained to represent the solubility of disperse dyes in SC-CO2. Numeric Sensitivity Analysis and Garson equation were utilized to find out the degree of effectiveness of different input variables on the efficiency of the proposed model. Results showed that our proposed ANN model has correlation coefficient, Nash–Sutcliffe model efficiency coefficient and discrepancy ratio about 0.998, 0.992, and 1.053 respectively.     

升温升压过程对聚丙烯在超临界水中降解的影响

The effect of increasing course of temperature and pressure on polypropylene （PP） degradation in supercritical water was investigated for developing a process of recycling waste plastic. A group of experiments was carded out in a reaction system at a pressure of 26MPa, temperature of 380℃ or 400℃ for 30min, 70min, and 120min by Course One （the increasing course of temperature and pressure is via gaseous regions to supercritical regions）, and the other group was carried out at corresponding holding conditions by Course Two （the increasing course of temperature and pressure is via liquid regions to supercritical regions）. The time of the increasing courses was about 30min. Products were analyzed by Ostward-type viscometer, gaseous chromatography, and mass spectrometers （GC/MS）. Characterization results suggested that different increasing courses of temperature and pressure would give rise to different results, although they were treated under the similar holding conditions. It was also found that Course Two was more effective on PP degradation in supercritical water.     

超临界 CO2萃取辣椒籽油的动力学研究简

A mathematical model for extraction of red pepper seed oil with supercritical CO2 was proposed. Some factors influencing the process were investigated, including operation pressure, temperature and extraction yield Xe （%）. The model was solved by the method of weighted residuals and used to simulate the process numerically. The kinetic equation is expressed as Xe =-16.8606exp（-t/9.98177） ＋ 16.95457 and the simulation results are in excellent agreement with the experimental data. The optimal operating parameters are 30 MPa, 318 K and 60 min.     

REACTIVE DYES CONTAINING(N-METHYL-β-SULFOETHYLAMINO)ETHYLSULFONYL GROUPS FOR SILK FIBRES

Silk dyeing with several classes of reactive dyes was studied.A class of reactive dyes con-taining(N-methyl-β-sulfoethylamino)ethylsulfonyl groups for silk is presented.A new method forintroducing such a reactive group and a kinetic studies on the reaction mechanism involved are pro-posed.A kinetic isotopic effect on dyeing mechanism with silk is discussed and the optimum dyeingtechniques recommended.Dyeing or printing was carried out in neutral media;brilliant shades,goodfastness,high fixation and excellent storage stability are given.     

REACTIVE DYES CONTAINING(N-METHYL-β-SULFOETHYLAMINO)ETHYLSULFONYL GROUPS FOR SILK FIBRES

Silk dyeing with several classes of reactive dyes was studied.A class of reactive dyes con-taining(N-methyl-β-sulfoethylamino)ethylsulfonyl groups for silk is presented.A new method forintroducing such a reactive group and a kinetic studies on the reaction mechanism involved are pro-posed.A kinetic isotopic effect on dyeing mechanism with silk is discussed and the optimum dyeingtechniques recommended.Dyeing or printing was carried out in neutral media;brilliant shades,goodfastness,high fixation and excellent storage stability are given.     

磁场对丙酮-水-三氯乙烷物系萃取过程的影响

In order to investigate the effect of magnetic field on the liquid-liquid extraction, the extraction in the acetone-water-trichloroethane system was studied under magnetic field with different magnetic induction intensity.The results showed that the effect of magnetic field was positive in the extraction process, and the partition coeffi-cient and the yield of acetone increased-with the increasing magnetic induction intensity by 5.16%-8.35% and 1.85%-5.70% respectively. The effect of magnetic field on the extraction was intensified when the temperature became, higher. The experimental data of the partition coefficient of acetone were correlated by the method of least square in terms of a power-law correlation.     

Fatty Acid Composition and Antioxidant Activity of Tea (Camellia sinensis L.) Seed Oil Extracted by Optimized Supercritical Carbon Dioxide

Seeds are another product in addition to leaves (raw materials for teas) of tea (Camellia sinensis L.) plant. The great increase of tea consumption in recent years raises the challenge of finding commercial applications for tea seeds. In the present study, supercritical carbon dioxide (SC-CO(2)) extraction edible oil from tea seed was carried out, response surface methodology (RSM) was used to optimize processing parameters including time (20-90 min), temperature (35-45 °C) and pressure (50-90 MPa). The fatty acid composition and antioxidant activity of the extracted oil was also investigated. The highest yield of oil (29.2 ± 0.6%) was obtained under optimal SC-CO(2) extraction conditions (45 °C, 89.7 min and 32 MPa, respectively), which was significantly higher (p < 0.05) than that (25.3 ± 1.0%) given by Soxhlet extraction. Meanwhile, tea seed oil extracted by SC-CO(2) contained approximately 80% unsaturated fatty acids and showed a much stronger scavenging ability on the DPPH radical than that extracted by Soxhlet. SC-CO(2) is a promising alternative for efficient extraction of edible oil from tea seed. Moreover, tea seed oil extracted by SC-CO(2) is highly edible and has good antioxidant activity, and therefore may play a potential role as a health-promoting food resource in human diets.     

基于超临界CO2制备熔体微分静电纺聚丙烯纤维

通过密封的压力容器将聚丙烯（PP）和超临界CO2混合,形成气固均相体系,采用熔体微分静电纺丝法制备PP和超临界CO2均相体系纤维;研究超临界CO2混合以及混合后形成的均相体系进行升温处理对制备纤维的影响。结果表明,纯PP、PP和超临界CO2混合后形成的均相体系以及对均相体系升温处理后,制备的纤维平均直径分别为12.8、8.02、5.08 μm;PP和超临界CO2混合后,聚合物的黏度得到降低;PP和超临界CO2混合后,制备的纤维结晶度得到降低。     

Supercritical CO2 extraction of lipids and astaxanthin from Brazilian redspotted shrimp waste (Farfantepenaeus paulensis)

Brazilian redspotted shrimp (Farfantepenaeus paulensis) waste is an important source of carotenoids such as astaxanthin and lipids with a high ω−3 fatty acids content, mainly docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). In order to establish an efficient and environmental friendly recovery process, the lipids and astaxanthin were extracted from the freeze-dried redspotted shrimp waste (including head, tail and shell) using supercritical carbon dioxide. The effects of the extraction conditions of pressure (200-400 bar) and temperature (40-60 °C) on the global yield (X₀), astaxanthin extraction yield and astaxanthin concentration in the extract were evaluated. It was found that the pressure and temperature showed a very low significant effect on the lipid extraction yield using supercritical CO₂. In comparison with lipid extraction by solvents, maximum efficiency of supercritical fluid extraction achieved 64% of hexane extraction yield. On the other hand, temperature and pressure had significant effects on astaxanthin extraction yield. Thegreatest amount of extract was obtained at 43 °C and 370 bar, with 39% of recovery.     

Supercritical direct extraction of neodymium using TTA and TBP

Extraction of a metal ion from its oxide using ligand assisted supercritical carbon dioxide (SC CO₂) comprises namely ionisation of metal oxide, in-situ chelation of metal cation with the ligand to form metal chelate/adduct and subsequently its extraction. Understanding of the mass transfer of chelate/adduct is very important in deciding the overall performance of the in-situ supercritical fluid extraction (ISCFE) process. For the present study neodymium (Nd) is selected as a model metal ion for its extraction from oxide using a mixed ligand system containing thenoyl tri-fluoroacetone (TTA) and tri-butylphosphate (TBP). Extraction studies have been performed at 35 MPa and 60°C for the prepared Nd-TTA-TBP adduct as well as for neodymium oxide (Nd₂O₃). The rate of dissolution starting from oxide and TTA-TBP adduct of Nd have been calculated and compared with the equilibrium values based on dissolution studies at the same conditions of temperature and pressure. During the extraction starting from oxide, the ligands TTA and TBP are also co-extracted with the adduct as these are highly soluble in SC CO₂. Mass transfer coefficient has also been estimated for the steady state during the dynamic extraction. It is observed that the rate of extraction and mass transfer coefficient increase with flow rate of SC CO₂.     

The analysis of simultaneous clove/oregano and clove/thyme supercritical extraction

The goal of present work was to investigate and explain kinetics and mass transfer phenomena occurring during the SFE from the mixture of two plants with different initial composition. The extractions from pure clove, oregano and thyme as well as from clove/oregano (C/O) and clove/thyme (C/T) mixtures with various initial compositions of plant material were carried out using supercritical CO₂ at 10 MPa and 40 °C. The results indicated that presence of light compounds in supercritical CO₂ originated from the oregano leaves or thyme at the beginning of extraction process increases the extraction rate of compounds from clove bud. Only small added amounts of oregano or thyme to clove bud (C/O - 90:10%, w/w; or C/T - 84:16%, w/w) in the starting plant mixture had the same effect resulted in the similar and the highest increase of the extraction rate and had negligible influence on total extraction yield compared to extract isolated from pure clove. Different mathematical models were used for simulation of experimental data which showed that the highest increase of the solubility of extractable compounds in supercritical CO₂ as well as the highest mass transfer rate in the solid phase during extractions existed during extraction from C/O (90:10, w/w) and C/T (84:16, w/w) mixtures. Decrease of SC CO₂ consumption or shorter time of extraction necessary for achieving desired extract yield in the case of SFE of the clove buds could be important for industrial-scale application.     

非均质多孔盐水层中超临界CO_2的注入压力与饱和度分布特性

为了研究盐水层孔隙结构特性对CO2注入过程的影响,采用对数正态分布的随机分布孔隙率表征地下盐水层的非均质孔隙特性,引入与盐水层中局部温度和局部压力相适应的CO2密度和黏度,建立了超临界CO2-盐水体系的两相流驱替过程数学模型。通过数值模拟研究了超临界CO2注入的过程参数和盐水层特性对CO2注入特性和盐水层中饱和度分布的影响。研究表明:CO2的注入压力主要与盐水层的深度和盐水层的体积平均孔隙率有关,而受盐水层孔隙率分布的影响较小;盐水层的孔隙率分布特性对CO2饱和度分布影响非常显著;在盐水层总容积相同的条件下,深层盐水层的CO2存储容量比浅层盐水层的小,且注入压力大;在CO2封存过程中,应选择合适的注入速率,最大限度地提高盐水层封存容量的利用率。本文的计算方法和分析结果为超临界CO2的地下封存过程和注入后的评估方法等提供了计算方法和理论依据。     

超临界二氧化碳萃取放射性金属离子研究进展

介绍了超临界二氧化碳（SF-CO₂）在镧系、锕系等放射性金属离子萃取中的应用。综述了近年来该领域的最新研究成果。讨论了SF-CO₂应用于核废料以及混合废物的后期处理中的可能性。     

Al2O3纳米颗粒对氨水鼓泡吸收过程的强化影响

在试制出了性能稳定的Al₂O₃纳米流体的基础上,通过定氨气流量和定入口压力两种实验方案,验证了Al₂O₃纳米颗粒对氨水吸收过程的强化影响,同时找出了引起强化吸收的两个主要影响因素：纳米流体性能的稳定性和吸收器入口与吸收器内气相界面的压力差。在添加十二烷基苯磺酸钠（SDBS）的情况下,可以获得性能稳定而具有强化吸收效果的Al₂O₃纳米流体,尽管SDBS本身对Al₂O₃纳米流体强化吸收具有抑制作用。较大的压力差下Al₂O₃纳米流体在吸收开始阶段就表现出强化吸收效果。随着氨水浓度的增加,氨水对氨气的吸收潜力减小,而Al₂O₃纳米流体对氨水溶液强化吸收的效果更加明显。对强化现象的可能机理给出了合理解释,为纳米流体对传热传质强化研究提供参考。     

负载型K2CO3/Al2O3二氧化碳吸收剂的碳酸化反应特性

The carbonation characteristics of K₂CO₃/Al₂O₃ supported sorbent for CO₂ capture was investigated with thermogravimetric apparatus（TGA）,X-ray diffraction（XRD）,scanning electron microscopy analysis（SEM）and N₂ adsorption.The results showed that the carbonation rate of K₂CO₃ before being loaded on Al₂O₃ was slow.However,the K₂CO₃/Al₂O₃ upported sorbent showed excellent carbonation performance.The difference in carbonation behavior between K₂CO₃ nd K₂CO₃/Al₂O₃ supported sorbent was analyzed from the microscopic view.The analytical reagent K₂CO₃ sample was of monoclinic crystal structure and could react quickly with H₂O in the experimental carbonation environment to produce K₂CO₃&#8226;1.5H₂O,which was unfavorable to carbonation reaction.When K₂CO₃was loaded on Al₂O₃,the surface area and porosity of the sorbent was improved greatly.So the carbonation properties of the K₂CO₃/Al₂O₃ supported sorbent was also improved.