PDMS/陶瓷复合膜用于正丁醇-水体系的渗透汽化分离

Pervaporation has attracted considerable interest owing to its potential application in recovering biobutanol from biomass acetone-butanol-ethanol (ABE) fermentation broth. In this study, butanol was recovered from its aqueous solution using a polydimethylsiloxane (PDMS)/ceramic composite pervaporation membrane. The effects of operating temperature, feed concentration, feed flow rate and operating time on the membrane pervaporation per-formance were investigated. It was found that with the increase of temperature or butanol concentration in the feed, the total flux through the membrane increased while the separation factor decreased slightly. As the feed flow rate increased, the total flux increased gradually while the separation factor changed little. At 40 C and 1% (by mass) butanol in the feed, the total flux and separation factor of the membrane reached 457.4 g•m2•h1 and 26.1, respec-tively. The membrane with high flux is suitable for recovering butanol from ABE fermentation broth.     

用CuO/A12O3/堇青石催化剂选择性催化还原脱硝的实验和动力学研究

The CuO/γ-Al2O3/cordierite catalyst, after being sulfated by sulfur dioxide (SO2) at 673 K, exhibits high activities for selective catalytic reduction (SCR) of nitrogen oxide (NO) with ammonia (NH3) at 573-723 K. The intrinsic kinetics of SCR of NO with NH3 over CuO/γ-Al2O3/cordierite catalyst has been measured in a fixed-bed reactor in the absence of internal and external diffusions. The experimental results show that the reaction rate can be quantified by a first-order expression with activation energy of 94.01 kJ•mol1 and the corresponding pre-exponential factor of 3.39×108 cm3•g1•s1 when NH3 is excessive. However, when NH3 is not enough, an Eley-Rideal kinetic model based on experimental data is derived with Ea of 105.79 kJ•mol1, the corresponding A of 2.94×109 cm3•g1•s1, heat of adsorption ΔHads of 87.90 kJ•mol1 and the corresponding Aads of 9.24 cm3•mol1. The intrinsic kinetic model obtained was incorporated in a 3D mathematical model of monolithic reactor, and the agreement of the prediction with experimental data indicates that the present kinetic model is adequate for the reactor design and engineering scale-up.     

硫酸铁改性颗粒活性氧化铝除氟的等温线研究

The adsorption equilibrium of a fluoride solution on 1-2 mm granular activated alumina modified by Fe2(SO4)3 solution was investigated. The experiments were conducted using a wide range of initial fluoride concentrations (0.5 to 180 mg•L1 at pH ~7.0) and an adsorbent dose of 1.0 g•L1. The application of Langmuir and Freundlich adsorption isotherm models (linear and nonlinear forms) generally showed that a single Langmuir or Freundlich equation cannot fit the entire concentration gap. Experimental data on low equilibrium concentrations (0.1 to 5.0 mg•L1) was in line with both Langmuir and Freundlich isotherm models, whereas that of high equilibrium concentrations (5.0 to 150 mg•L1) was more in line with the Freundlich isotherm model. A new Langmuir- Freundlich function was used for the entire concentration gap, as well as for low and high concentrations.     

氨改性的介孔二氧化硅的直接合成和CO2吸附

Amine-functionalized mesoporous silica was prepared by using lauric acid and N-stearoyl-l-glutamic acid as structure directing agents via the SN+-I mechanism and applied to CO2 adsorption at room temperature. With γ-aminopropyltriethoxysilane as co-structure directing agent and due to the direct electrostatic interaction with anionic surfactant, most of the amino groups were uniformly distributed at the inner surface of pores and the performance was stable. The amine-functionalized mesoporous silica was characterized by Fourier transform infrared spectrometer, X-ray diffraction, nitrogen physisorption and thermogravimetric analysis. The CO2 adsorption capacity was measured by digital recording balance. At the room temperature and under the atmospheric pres-sure, the adsorption capacity of LAA-AMS-0.2 for CO2 and N2 is 1.40 mmol•g1 and 0.03 mmol•g1, respectively, indicating high separation coefficient of CO2/N2.     

盐对水+丙酸+环乙醇三相体系在298.2，303.2和308.2 K下液液相平衡的影响

Effects of salt and temperature on the liquid phase equilibrium of the (water + propionic acid + cyclohexanol) system were investigated. The liquid-liquid equilibrium data in the presence of KCl for various salt ionic strength of 0.5, 1.0, 1.5, 2.0, and 2.5 mol•dm3 and in absence of the salt at T (298.2, 303.2, and 308.2) K were determined. The experimental results were correlated based on the Othmer-Tobias equation and Pitzer ion-interaction model. Thermodynamic properties such as distribution coefficients and activity coefficients of propionic acid in water + cyclohexanol were determined. In addition, the separation factor, S, of the chosen solvent was obtained for the investigated system.     

La(III) Transport in Dispersion Supported Liquid Membrane Including PC-88A as the Carrier and HCl Solution as the Stripping Solution

The transport of La(III) through a dispersion supported liquid membrane with polyvinylidene fluoride membrane as the liquid membrane support and dispersion solution including HCl solution as the stripping solution and 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (PC-88A) in kerosene as the membrane solution, was studied. As a result, the optimum transport conditions of La(III) were obtained as that concentration of HCl solution was 4.0 mol/L, concentration of PC-88A 0.16 mol/L, and volume ratio of membrane to stripping solution 30:30 in the dispersion phase, and pH value 4.0 in the feed phase. Ionic strength had no obvious effect on the transport of La(III). Under the optimum conditions, when initial concentration of La(III) was 0.8′10-4 mol/L, the transport rate was up to 96.3% during the transport time of 125 min. The kinetic equation was developed based on the law of mass diffusion and theory of interface chemistry. The diffusion coefficient of La(III) in the membrane and the thickness of diffusion layer between feed and membrane phases were obtained as 3.20′10-7 m2/s and 3.22′10-5 m, respectively. The calculated results were in good agreement with experimental results.     

椰油丙基酰胺甜菜碱/聚乙二醇水溶液的分相研究

Phase separation behavior of cocamidopropyl betaine/water/polyethylene glycol (PEG) system was studied. The effects of concentration and molecular weight of PEG on the phase separation behavior were investigated. Clouding occurred when the con-centration of PEG was large enough in the betaine aqueous solution, and the concentration of PEG at cloud point decreased with the increase of PEG molecular weight for a constant betaine concentration. The bottom phase was the PEG-rich phase, and the upper phase was the betaine-rich phase. The volumetric ratio of PEG-rich phase to betaine-rich phase, at the same difference between the PEG concentration and the one at the cloud point, Ccp (0.1 g•ml－1), decreased as the PEG molecular weight increased and approached 1 for higher PEG molecular weight (about 20000), which was similar to the typical aqueous two-phase system. This volumetric ratio depended on the initial PEG concentration, but independent of PEG molecular weight. The concentration ratio of betaine to PEG in both phases depended on the Ccp, independent of PEG molecular weight.     

中空纤维支撑液膜萃取Cu(II)的传递性能

The transport of Cu(II) from aqueous solutions containing buffer media through hollow fiber supported liquid membrane (HFSLM) using di(2-ethylhexyl) phosphoric acid (D2EHPA) dissolved in kerosene as membrane phase and hydrochloric acid as striping phase was investigated. A set of factors were studied, including tube side velocity, shell side velocity, pH of the feed phase, Cu(II) concentration in the feed phase, buffer media concentration and D2EHPA concentration in the membrane phase. Experimental results indicate that the mass transfer coefficient increases with increasing both carrier concentration in the organic phase and flow rates on the tube side and shell side, and decreases with increasing initial Cu(II) concentration in the feed phase. With increasing pH value and acetate concentration in the feed phase, the mass transfer coefficient reaches a maximum value then decreases. The optimal operating conditions are obtained at pH value of 4.44 and 0.1 mol&;#8226;L－1 acetic ion concentration in feed phase, and carrier volume fraction of around 10% in kerosene as organic phase. A mathematical model of the transport mechanism through HFSLM is devel-oped. The modeled results agree well with the experimental ones.     

响应面方法分析代谢产物对类人胶原蛋白表达的影响

Recombinant Escherichia coli BL21 is used to produce human-like collagen. The key constituents of media are optimized using response surface methodology (RSM). Before thermal induction, the highest biomass production and the lowest production of some hazardous by-products, especially acetic acid, were obtained in the media containing 0.085 mol∙L1 glucose and 0.019 mol∙L1 nitrogen (carbon-nitrogen ratio, 4.47︰1). After thermal induction, when the concentrations of glucose and nitrogen in the media were 0.065 mol∙L1 and 0.017 mol∙L1, respectively (carbon-nitrogen ratio, 3.82︰1), the productivity of human-like collagen per cell was the highest while that of acetic acid was the lowest. The extended analysis showed that the production of lactic acid and propionic acid increased while that of some intermediate acids of the tricarboxylic acid cycle decreased if the dose of glucose in-creased.     

以正硅酸乙酯和1,2-二(三乙氧基硅基)乙烷为前驱体制备微孔SiO2复合膜及其气体分离性能

This paper reports on ¬¬¬a new microporous composite silica membrane prepared via acid-catalyzed polymeric route of sol-gel method with tetraethylorthosilicate (TEOS) and a bridged silsesquioxane [1, 2-bis(triethoxysilyl)ethane, BTESE] as precursors. A stable nano-sized composite silica sol with a mean volume size of ~5 nm was synthesized. A 150 nm-thick defect-free composite silica membrane was deposited on disk support consisting of macroporous α-Al2O3 and mesoporous γ-Al2O3 intermediate layer by using dip-coating ap-proach, followed by calcination under pure nitrogen atmosphere. The composite silica membranes exhibit molecular sieve properties for small gases like H2, CO2, O2, N2, CH4 and SF6 with hydrogen permeances in the range of (1-4)107 mol•m2•s1•Pa1 (measured at 200 C, 3.0×105 Pa). With respect to the membrane calcined at 500 C, it is found that the permselectivities of H2 (0.289 nm) with respect to N2 (0.365 nm), CH4 (0.384 nm) and SF6 (0.55 nm) are 22.9, 42 and >1000, respectively, which are all much higher than the corresponding Knudsen values (H2/N2 3.7, H2/CH4 2.8, and H2/SF6 8.5).     

分散支撑液膜中四价铈的传输分离

研究了以聚偏氟乙烯膜(PVDF)为液膜支撑体,煤油为膜溶剂,2-乙基己基磷酸-单-2-乙基己基酯(PC-88A)为流动载体,煤油和PC-88A的混合溶液作为膜溶液,膜溶液和HCl溶液组成分散相的分散支撑液膜(DSLM)中Ce(IV)的传输行为;考察了料液相酸度、Ce(IV)起始浓度、HCl浓度、膜溶液与HCl溶液体积比、解析剂及载体浓度对Ce(IV)传输的影响,得出其最优传输分离条件为：HCl浓度4.0 mol/L,膜溶液与HCl溶液体积比2:1,载体浓度0.16 mol/L,料液相中HCl浓度0.1 mol/L. 在最优条件下,料液相中Ce(IV)的初始浓度为0.7′10-4 mol/L时,迁移75 min,其迁移率达到96.3%. 提出了Ce(IV)在DSLM中的传质动力学方程,得出Ce(IV)在膜中的扩散系数为6.69′10-8 m2/s,料液-膜边界层厚度为19.3 mm. 对模拟样品Ce(IV)的分离结果表明,在一定条件下,125 min内模拟煤粉灰中Ce(IV)迁移率达到92.8%;105 min内模拟冶金熔渣中其迁移率可达92.6%;215 min内Ce(IV)与Eu(III)的混合液中Ce(IV)迁移率达到83%,其他元素迁移率极低.     

巯基乙酸2—乙基己酯的合成

本文介绍了巯基乙酸2-乙基己酯产品的用途、性能以及合成路线。以2-乙基己醇和氯乙酸为起始反应原料,采用先酯化后巯基化的合成工艺,催化剂活性高、反应步骤少、产品收率高,解决了先巯基化后酯化工艺过程复杂、对巯基乙酸纯度要求高、生产成本高的难题,是具有较高工业化实践价值的新生产工艺。     

Studies on the Recovery of Uranium from Phosphoric Acid Medium by D2EHPA/n-Dodecane Supported Liquid Membrane

Abstract

Present studies deal with the application of supported liquid membrane (SLM) technique for the separation of uranium (VI) from phosphoric acid medium using Di-2 ethyl hexyl phosphoric acid (D2EHPA)/n-dodecane as a carrier and ammonium carbonate as a receiving phase. The studies involve the investigation of process controlling parameters like feed acidity of phosphoric acid, carrier concentration, stripping agents, and the effect of thickness and the pore size of the membrane. The transport of uranium decreases with increase in the concentration of phosphoric acid in feed solution whereas it increases with increase in carrier concentration in supported liquid membrane. More than 90% uranium (VI) is recovered in 360 minutes using 0.5 M D2EHPA/dodecane as carrier and 0.5 M ammonium carbonate as stripping phase from the 0.001 M H₃PO₄ feed. Lower concentration of phosphoric acid and higher carrier concentration is found to be the most suitable condition for maximum transport of uranium (VI) from its lean sources like commercial phosphoric acid and analytical wastes generated from the analysis of uranium by Volumetric (Davis-Gray) method.     

复合固体超强酸SO_4~(2-)/ZrO_2-TiO_2催化合成邻苯二甲酸二(2-乙基己酯)

以复合固体超强酸SO42-/ZrO2-TiO2为催化剂合成了邻苯二甲酸二(2-乙基)己酯(DOP),考察了催化剂用量、投料比和反应终点温度对反应的影响,用傅立叶变换红外光谱对产品进行了结构表征。结果表明,该工艺优化条件为:催化剂用量为总投料量为0.6%(质量分数),投料比n(苯酐)∶n(2-乙基己醇)为1∶(2.3～2.4),反应终点温度205～215℃,反应时间2.3h,酯化率达99.5%以上,产品质量达到或超过国家优级品标准,催化剂可重复使用5次,酯化率仍在99%以上,无腐蚀,环境污染小,催化剂再生容易。     

Carrier Mediated Transport of Thorium from Nitric Acid Medium using 2-Ethyl Hexyl Hydrogen 2-Ethyl Hexyl Phosphonate (PC88A)/N-Dodecane as Carrier

The present study deals with the application of supported liquid membrane (SLM) technique for the separation of thorium from nitric acid medium using 2-ethyl hexyl hydrogen 2-ethyl hexyl phosphonate (PC88A) as a carrier and aqueous ammonium carbonate as a receiving phase. The effects of feed acidity, nature of strippant, and membrane pore size and membrane thickness on the transport of thorium have been studied in detail. Transport behavior of uranium (²³³U) and fission products from a radioanalytical laboratory waste is also studied. Stability of the membrane against the leaching of the extractant and stability of the membrane support have been investigated. An attempt has been made to model the physicochemical transport of thorium in SLM and establish the mechanism of thorium transport. Transport of thorium increased from 25% to about 96% using 0.75 M PC88A in n-dodecane as carrier and 2 M ammonium carbonate as stripping phase as the feed acidity decreased from 4 M HNO₃ to 0.5 M HNO₃. Optimum conditions obtained from this study were applied to recover thorium and ²³³U from analytical waste generated in the laboratory.     

Separation of yttrium from europium using a hollow fiber-supported liquid membrane with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester as an extractant

The separation of Y(III) from Eu(III) using a hollow fiber-supported liquid membrane with 2-ethylhexyl phosphonic acid mono-2-ethylhexyl ester (EHPNA) as an extractant was studied. The effects of HCl and metal concentrations in the feed solution, the EHPNA concentration in the membrane, and the HCl concentration in the stripping solution on the initial fluxes of the two metals and the separation factor were investigated. The optimum conditions for selective recovery of Y(III) from an equimolar solution of Y(III) and Eu(III) chlorides (0.001?mol?L^?1 each) were as follows: HCl concentration in the feed solution, 0.1?mol?L^?1; EHPNA dimer concentration in the organic phase in the membrane, 0.1?mol?L^?1; and HCl concentration in the stripping solution, 4?mol?L^?1. Under these conditions, complete Y(III) extraction was achieved after 1 ks of operation, and the Y(III) purity in the stripping solution was 84%.     

Mass transfer of cadmium ions in a hollow-fiber module by pertraction

The facilitated transport of Cd(Il) ions through a hollow-fiber-supported liquid membrane with bis-2-ethylhexyl phosphoric acid as carrier was studied. The mass transfer rate, expressed as permeability P, was measured as a function of mean aqueous solution velocity and carrier concentration. Characteristic ion permeabilities of 10-26 × 10⁻⁷ m/s were measured at feed velocities between 1 × 10⁻²−19 × 10⁻² m/s at stripping velocities between 0.22 × 10⁻²−7x 10⁻² m/s with constant feed flow. The measured permeabilities were compared to generally accepted mass transfer correlations. The predicted permeabilities adequately fit the experimental data, indicating that the rate limiting step in the transport of the ion was the diffusion through both aqueous films, feed and stripping, whereas the organic resistance of the membrane was negligible. Furthermore, the proposed model allowed the prediction of the permeability of cadmium for different experimental conditions, which is useful to perform experiments to reduce metal levels in water or other effluents.     

Studies on permeation of uranium (VI) from phosphoric acid medium through supported liquid membrane comprising a binary mixture of PC88A and Cyanex 923 in n-dodecane as carrier

Present studies deal with the application of supported liquid membrane (SLM) technique for the separation of uranium (VI) from phosphoric acid medium using a binary mixture of 2-ethyl hexyl phosphoric acid-mono-2-ethyl hexyl ester (PC88A) and neutral donor which is a mixture of four tri-alkyl phosphine oxide better known as Cyanex 923 in n-dodecane as a carrier and (NH₄)₂CO₃ as a receiving phase. Various parameters like feed acidity, nature of strippant, carrier concentration, membrane pore size, membrane thickness etc. which affect the transport of U(VI) have been studied in detail. Experiments have also been carried out to see the transport behaviour of different fission products from a diluted High Level Waste (HLW) solution. Stability of the membrane against the leaching of the extractant and stability of the membrane support have also been investigated. We have tried to model the physicochemical transport of U(VI) in SLM as well as establishing the mechanism (Diffusion controlled) of transport. More than 95% uranium (VI) is recovered in 360 min using a binary mixture of 0.60 M PC88A and 0.15 M Cyanex 923 in n-dodecane as carrier and 0.5 M (NH₄)₂CO₃ as stripping phase from the 0.5 M H₃PO₄ feed. Lower concentration of H₃PO₄ (0.5 M) and optimum carrier concentration (0.60 M PC88A + 0.15 M Cyanex 923) in the mole ratio of 4:1 is found to be the most suitable condition for maximum transport of uranium (VI). The optimum conditions obtained from this study was also applied to recover uranium from analytical waste in phosphoric acid medium generated in the laboratory.     

SnO_2-高岭土负载硫酸镓催化合成己酸己酯

SnC l4.5H2O和高岭土的质量比1∶3,饱和Ga2(SO4)3溶液浸渍4 h,300℃焙烧2 h,制备了以Ga2(SO4)3为活性组分、SnO2-高岭土为载体的负载型酯化催化剂。用于正己酸与正己醇合成己酸己酯酯化反应,考察了催化剂用量、n(正己醇)∶n(正己酸)、反应时间、带水剂种类及用量等因素对酯化率的影响。结果表明,合成己酸己酯的适宜反应条件为:n(正己醇)∶n(正己酸)=1.4,苯15 mL,催化剂用量为反应物总质量的3.0%,反应时间100 min,酯化率为98.8%。该催化剂催化活性高、成本低、制备方法简单,并且易分离回收。