用于芳烃/烷烃体系蒸汽渗透分离的离子液体支撑液膜研究

研究离子液体"填充型"支撑液膜制备规律,以及操作条件对苯/环己烷混合物蒸汽渗透分离过程影响。利用[C4mim][BF4]、[C8mim][BF4]、[C4mim][PF6]、[C6mim][PF6]、[4-Mebupy][BF4]、[3-Mebupy][BF4]离子液体分别制备支撑液膜,用于苯/环己烷混合物蒸汽渗透膜分离过程研究。实验比较了离子液体的种类、操作温度、原料液浓度等因素对苯/环己烷混合体系的蒸汽渗透膜分离性能的影响,其中[3-Mebupy][BF4]制得的支撑液膜对等体积配比的苯和环己烷混合物分离效果最佳,30℃时渗透通量为11.4g?m2?h?1,分离因子可达32.85。通过长时间运行的稳定性实验,证实离子液体支撑液膜的蒸汽渗透过程能够实现苯和环己烷的有效分离,具备良好的稳定性。离子液体"填充型"支撑液膜有望成为降低芳烃/烷烃等有机溶剂体系分离过程能耗的有效途径。     

离子液体支撑液膜用于分离混合芳烃的研究

利用不同离子液体制备离子液体"充填型"支撑液膜,将其用于混合芳烃中对二甲苯的蒸汽渗透膜分离实验,比较了不同离子液体、不同支撑底膜、原料中对二甲苯的含量、操作温度等因素对分离性能的影响。结果表明,在40℃温度下,[Bmim][BF4]填充PVDF膜形成的支撑液膜对对二甲苯体积分数为60%的混合芳烃渗透通量为59.5 g/(m2·h),分离因子达16.5;经过90 h的实验测定,支撑液膜分离性能稳定。离子液体支撑液膜的蒸汽渗透过程能够实现从混合芳烃中将对二甲苯分离。     

离子液体支撑液膜用于分离混合芳烃的研究

利用不同离子液体制备离子液体"充填型"支撑液膜,将其用于混合芳烃中对二甲苯的蒸汽渗透膜分离实验,比较了不同离子液体、不同支撑底膜、原料中对二甲苯的含量、操作温度等因素对分离性能的影响。结果表明,在40℃温度下,[Bmim][BF4]填充PVDF膜形成的支撑液膜对对二甲苯体积分数为60%的混合芳烃渗透通量为59.5 g/(m2·h),分离因子达16.5;经过90 h的实验测定,支撑液膜分离性能稳定。离子液体支撑液膜的蒸汽渗透过程能够实现从混合芳烃中将对二甲苯分离。     

离子液体支撑液膜的CO2/CH4分离性能

由于离子液体对CO₂具有较好的溶解选择性,离子液体支撑液膜分离CO₂越来越受到关注。比较了含3种不同阴离子的常规离子液体([bmim][BF₄]、[bmim][PF₆]、[bmim][Tf₂N])作为支撑液膜的液膜相分离CO₂/CH₄的性能,考察了咪唑环上烷基链长对离子液体支撑液膜性能的影响。考虑向离子液体中引入胺基和羧基等亲CO₂基团,制备了1-丁基-3-甲基咪唑丙氨酸离子液体([bmim][β-Ala]),考察了 [bmim][β-Ala]支撑液膜分离CO₂/CH₄的性能,并对在CO₂渗透测试前后的支撑液膜进行了FT-IR分析,发现氨基酸离子液体中的-NH₂和CO₂的较强作用以及该离子液体的高黏性影响了CO₂的透过性,使[Bmim][β-Ala]支撑液膜的CO₂透过率低。     

室温离子液体辅助制备纳米TiO_2研究进展

评述了离子液体[Bmim][BF4]、[Bmim][PF6]、[C2OHmim]Cl、[C2OHmim][BF4]、[Emim][Tf2N]、[Emim][AcO]、[Acmim]Br等在制备纳米TiO2中的应用。在采用溶胶-凝胶法、水热法、微波辅助法和电化学法制备纳米TiO2时,离子液体可作为溶剂和稳定剂。与其它溶剂相比,在离子液体中制备的纳米TiO2具有更细的粒度以及更好的分散性。指出了离子液体用于制备纳米TiO2存在的问题和今后研究的方向。     

胆碱脯氨酸/RTILs支撑液膜的CO2/N2分离性能

选用不同种类的室温型离子液体（RTILs）与胆碱脯氨酸离子液体进行混合分别制得[Choline][Pro]/[EMIm][N（CN）₂]、[Choline][Pro]/[bmim][PF₆]以及[Choline][Pro]/[HMIm][NTf₂]混合离子液体,并将其应用于离子液体支撑液膜（SILMs）。考察操作温度、操作压差、RTILs种类和含量对SILMs分离CO₂/N₂性能的影响。结果表明胆碱脯氨酸/RTILs系列SILMs的CO₂通量在343.3～1936.9 barrer之间变化并且CO₂/N₂选择性为10.3～34.8。对CO₂膜过程内在机制探索表明随着[HMIm][NTf₂]离子液体在混合离子液体中比例的增加,总阻力1/K_m会呈现先降低后升高的趋势。与实验现象中随着[HMIm][NTf₂]离子液体在混合离子液体中比例的增加CO₂先升高后降低相符。     

水对离子液体微观结构和传输性能的影响

离子液体以独特的结构性质和优异的物化性能而显示出日益广阔的应用前景,但实际应用中,不可避免的混入一些水,水的存在会对离子液体结构和性质产生显著影响.本工作采用分子动力学模拟方法系统研究了不同含量的水对三种离子液体([Bmim][B(CN)4],[Bmim][PF6]和[Bmim][Tf2N])微观结构、传输性能和相互作...     

离子液处理过程中稻秸超微构造的变化

采用1-丁基-3-甲基咪唑氯盐([Bmim][Cl])和氯化胆碱―尿素离子液处理稻秸,探讨离子液用量、处理温度、处理时间对稻秸分离率和表面形貌的影响规律。结果显示,[Bmim][Cl]和氯化胆碱―尿素离子液均能分离稻秸。分离过程中,处理温度对分离效果的影响显著高于时间。在110℃,[Bmim][Cl]和氯化胆碱―尿素离子液对稻秸的分离率相当,在130℃,氯化胆碱―尿素对稻秸的分离率显著高于[Bmim][Cl]离子液。经离子液处理后,稻秸中木素纤维素被溶出,二氧化硅含量增加。通过扫描电子显微镜观察,[Bmim][Cl]和氯化胆碱―尿素离子液分离稻秸时,离子液首先攻击稻秸的内表面,然后逐渐渗入到稻秸内部,从内表面贯穿到外表面,内表面破坏的程度高于外表面。经离子液分离后稻秸外表层颗粒物形貌基本保持不变。     

超临界流体沉积制备[Emim][BF4]支撑型离子液体膜及其气体分离性能

为了进一步提高支撑型离子液体膜的制备效率及其CO2气体分离性能,将离子液体[Emim][BF4]以超临界流体沉积法负载到非对称的Al2O3支撑体内,制备了一系列支撑型离子液体膜,分别测定了CO2和N2两种纯气体在其中的渗透率,探究了制备参数(沉积时间、离子液体加入量和共溶剂加入量)对膜性能的影响规律.结果表明,基于[E...     

CO2／[Bmim]Br-AICl3／苯体系相平衡研究

在温度40-80℃、压力1．50～1200MPa条件下,测定了CO2在氯铝酸离子液体（[Bmim]Br-AICl3）中的溶解度;在60℃以及3．00-10．00MPa条件下,测定了CO3／[Bmim]Br-AICl3／苯三元体系中气液相平衡数据,获得了三组分物系的相图。实验结果表明：在低压条件下,CO2在离子液体中的溶解度（XCO2）随压力增加而升高：当温度在40～80℃、压力9．00-10．00MPa范围内,XCO2分别达到最大值。在CO2／[Bmim]Br-AICl3苯三元体系中,根据各组分的最初摩尔比的不同,平衡体系中分别会出现气．液两相及气．液一液三相。压力对富苯相中各组分影响较富离子液体更大：在60℃,1O．00MPa条件下,体系中有颓相生成,气-液两相区转变为气-液-液三相区。     

Separation of Liquid Solutions by Contained Liquid Membranes

Abstract

The technique of contained liquid membranes (CLM) for liquid solution separation is discussed. The CLM is obtained by confining the membrane liquid between two sets of microporous hollow fibers (MHF). The lumen of the hollow fiber carries the feed or the strip solution under proper phase pressure condition vis-a-vis the membrane phase. Various possible structural configurations of the CLM are illustrated with respect to the nature of microporous hollow fiber substrate, the feed solution and the liquid membrane. The contributions of different resistances to the solute transport rate are identified. Some basic experimental data obtained in small CLM permeators are presented for two systems with organic liquid membranes to illustrate how steady state separation is achieved after an initial unsteady period. The considerable advantages of the CLM structure over more traditional liquid membrane techniques such as supported liquid membrane (SLM) with respect to membrane stability, membrane regeneration and feed equilibration are pointed out.     

中空纤维PVA/PAN复合膜填料的乙醇水溶液精馏性能

以乙醇/水溶液为分离对象,中空纤维PVA/PAN复合膜作为精馏填料,考察了不同膜组件的传质分离效率。实验结果表明:各种组件的分离效率均随塔釜加热功率的增加而减小;和大多数中空纤维膜接触器一样,其总传质系数Ky随中空纤维膜组件填充密度φ的增加而减少;相比于传统精馏填料而言,用中空纤维膜做精馏填料分离乙醇水溶液的分离效果更好,可以在常规填料不能操作的液泛线以上进行操作。当塔釜加热功率为120 W,45根中空纤维膜封装在内径为1.6 cm玻璃管中的传质单元高度(HTU)为5.64 cm。     

Multivariate Analysis of Selected Metal Ion Transport through a Hollow‐Fiber Supported Liquid Membrane Device used for Passive Sampling Monitoring

A hollow fiber supported liquid membrane module using one single fiber impregnated with a mixture of 1,10‐dibenzyl‐1,10‐diaza‐18‐crown‐6 and bis(2‐ethylhexyl)phosphate dissolved in hexylbenzene was used for passive sampling of ppb levels of Pb(II), Cu(II), Zn(II), Mn(II), Ni(II), and Cd(II) in water. The target ions were simultaneously transported and preconcentrated into a citric acid acceptor solution within the lumen of the hollow fiber with enrichment factors between 5 and 4000 times. A multivariate analysis of several physical and chemical parameters that affect transport was performed. Under conditions of constant concentration profiles a more robust performance of the device was observed.     

Comparison of Bulk,Emulsion, Thin Sheet Supported,and Hollo Fiber Supported Liquid Membranes in Macrocycle-Mediated Cation Separations

Abstract

The advantages, disadvantages, and possible applications of macrocycle-mediated bulk, emulsion, supported and hollow fiber liquid membranes have been investi-gated. The relative transport rates of the alkali metal cations and of Zn(II), Cd(II) and Hg(II) in sin-gle and competitive cation experiments are studied and compared in the different membrane types. The four membrane types demonstrate similar selectivities but significantly different cation fluxes under comparable conditions using analogous macrocyclic carriers. The degree of distribution of the macrocycle to the organic membrane which is necessary for significant transport varies dramatically among the membrane types, each of which requires unique solvent characteristics. In the experiments, either l8-crown-6, dicyclohexano-l8-crown-6, or 4,1′(5)bis(1-hydroxyheptylcyclohexano)-l8-crown-6 were incorporated into bulk (chloroform, raethylene chloride), emulsion (toluene), supported (phenylhexane) and hollow fiber (phenylhexane or 1-octanol) liquid membranes with the membrane solvents shown in parentheses.     

中空纤维更新液膜处理含镍电镀废水

利用自制疏水聚偏氟乙烯(PVDF)中空纤维膜组件对中空纤维更新液膜处理含镍电镀废水过程中的影响因素进行了研究,考察了液膜两侧液相浓度、流速、萃取剂P204所占油相比例等因素对镍去除率的影响.并把中空纤维更新液膜和中空纤维支撑液膜处理效果进行了对比.     

Recovery of Copper Ions from Wastewater by Hollow Fiber Supported Emulsion Liquid Membrane

Recovery of copper ions from wastewater using a hollow fiber supported emulsion liquid membrane (HFSELM) was studied with LIX984N as carrier, kerosene as diluents, and sulfuric acid solution as strippi...     

Polyvinyl alcohol/polysulfone (PVA/PSF) hollow fiber composite membranes for pervaporation separation of ethanol/water solution

Polysulfone (PSF) hollow fiber membranes were spun by phase‐inversion method from 29 wt % solids of 29 : 65 : 6 PSF/NMP/glycerol and 29 : 64 : 7 PSF/DMAc/glycol using 93.5 : 6.5 NMP/water and 94.5 : 5.5 DMAc/water as bore fluids, respectively, while the external coagulant was water. Polyvinyl alcohol/polysulfone (PVA/PSF) hollow fiber composite membranes were prepared after PSF hollow fiber membranes were coated using different PVA aqueous solutions, which were composed of PVA, fatty alcohol polyoxyethylene ether (AEO₉), maleic acid (MAC), and water. Two coating methods (dip coating and vacuum coating) and different heat treatments were discussed. The effects of hollow fiber membrane treatment methods, membrane structures, ethanol solution temperatures, and MAC/PVA ratios on the pervaporation performance of 95 wt % ethanol/water solution were studied. Using the vacuum‐coating method, the suitable MAC/PVA ratio was 0.3 for the preparation of PVA/PSF hollow fiber composite membrane with the sponge‐like membrane structure. Its pervaporation performance was as follows: separation factor (α) was 185 while permeation flux (J) was 30g/m²·h at 50°C. Based on the experimental results, it was found that separation factor (α) of PVA/PSF composite membrane with single finger‐void membrane structure was higher than that with the sponge‐like membrane structure. Therefore, single finger‐void membrane structure as the supported membrane was more suitable than sponge‐like membrane structure for the preparation of PVA/PSF hollow fiber composite membrane. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 98: 247–254, 2005     

Intensification of zirconium and hafnium separation through the hollow fiber renewal liquid membrane technique using synergistic mixture of TBP and Cyanex-272 as extractant

The novel synergistic mixture of TBP and Cyanex-272 is used as the extractant in the hollow fiber renewal liquid membrane(HFRLM) technique for Zr/Hf separation.The effects of the chemical and operational parameters such as HNO_3 concentration in the donor phase,NH4 F concentration in the acceptor phase,Cyanex-272 and TBP concentration in the liquid membrane phase,the lumen and shell side flow rates,and aqueous/organic volume ratio on the mass transfer and separation performance of HFRLM method were investigated.The obtained results reveal the intensification potential of proposed HFRLM technique for selective extraction of Zr over Hf with separation factor higher than 100.The HFRLM method provides two times higher mass transfer flux in comparison with hollow fiber supported liquid membrane(HFSLM).Also,the HFRLM method shows satisfactory stability for 700 min of continuous operation.The Zr ion transport through the LM phase follows the coupled co-transport mechanism and the diffusion in the renewal layer is recognized as the rate-controlling step in the HFRLM process.Moreover,the Zr mass transfer coefficient and molar flux in the HFRLM method are calculated in the range of 1×10~(-8)to 8.4×10~(-7) m·s~(-1) and 4.9×10~(-6) to 20.1×10~(-6) mol·m~(-2)·s~(-1),respectively.     

Reduction of concentration polarization at feeding interphase of a hollow fiber supported liquid membrane by using periodic operation

An experimental investigation was carried out to reduce the concentration polarization at feeding interphase between feed solution and liquid membrane imposing flow instabilities. The periodic operation of the hollow fiber supported liquid membrane for separation of lanthanide metal by using D2EHPA as extractant dissolved in kerosene. The operating flow rate of the feed solution was varied according to a symmetric square wave function around time-average values of 200, 300 and 400 ml/min. Time periods ranging from 18 to 3 minutes and amplitudes of 50 and 100 ml/min were investigated. The results of these periodic tests were compared with results obtained from the conventional steadystate mode of operation. It has been found that the periodic operation leads to higher stripping concentration or higher ion flux than that obtained from the corresponding steady state operating conditions. This is because periodic operation disturbs concentration polarization in the boundary layer between the feed solution and liquid membrane. It has also been found that the ion flux increases with increasing amplitudes and decreasing time periods of the forcing function. However, when the period is less than 3 minutes the flux decreases because the liquid membrane is peeled out from the pores of hollow fiber.     

A Mathematical Analysis of Membrane Separation Parameters for Liquid/Liquid Dialysis in Single or Multiple Stages

Abstract

The effects of membrane separation parameters using liquid/liquid dialysis under idealized conditions and using hollow fiber geometry were calculated with the aid of a computer. These calculations were carried out for both single stage and multiple stages. Membrane separation parameters include the intrinsic properties of the membrane, the nature of the dialysis solvents, the flow rates of both feed and solvent streams, and the dimension of the hollow fiber. It was concluded that an efficient process using liquid/liquid dialysis requires a membrane with a high intrinsic permeability constant and a reasonable separation factor, as small an inner radius of hollow fiber as is practical, and a dialysis solvent with an acceptable activity coefficient for the key species and a flow rate suitably coupled to that of the feed.