膜基溶剂萃取法提取锌的研究

膜基溶剂萃取法是一种新型的分离技术。它利用多孔膜将有机相和水相分开,然后在微孔的接触界面上进行传质。该过程没有两相的分散和凝聚过程。本文以HDEHP-煤油和硫酸锌溶液为体系,研究了萃取过程中两相流量对传质过程的影响,并求取以水相为基准的总传质系数。同时也研究了HDEHP-煤油和硫酸水溶液的反萃取体系。结果表明在萃取时膜相和有机相边界层的阻力比较小;在反萃取时膜相和有机相边界层的阻力不可忽略。     

固定膜界面萃取的研究

固定膜界面萃取是一种新型分离方法。与有机溶剂直接和水溶液混合接触的通常萃取过程不同,溶剂与水溶液的接触是在膜孔界面上进行的。谈过程没有两相的聚结和澄清。本文(?)50%TBP(煤油(?)—HAC—H_2O和30%P204(煤油)—ZnSO_4H_2O为体系研究丁这一技术,求取了基于有机相的总传质系数。尽管膜传质阻力可能减缓传质速率,然而,微孔中空(?)膜器提供了比通常萃取器大得多的比表面积,体积萃取速率将会明显加快     

中空纤维膜萃取苯酚的传质及流动特性

以体积分数为30％的磷酸三丁酯＋煤油－水为实验体系，研究了中、高装填密度的中空纤维膜萃取处理苯酚衡溶液的传质效果和传质特性以及膜器壳程流动状况。实验结果表明，中空纤维膜萃取可以高效去除水中的苯酚，萃取率最高可达到99．9％。比较了总传质系数的实验值与多个传质系数关联式的预测值之间的偏差，发现从中、高装填密度膜器得到的传质关联式偏差较小，而从低装填密度膜器得到的传质关联式偏差较大。通过测量膜器壳程流动的停留时间分布曲线，证实了偏差是由于中、高装填密度的膜器壳程流动的复杂性造成的。     

螺旋状中空纤维膜萃取传质特性

在对中空纤维膜萃取以及螺旋管技术进行充分调研的基础上 ,选择水 -苯酚 - 30 %TBP煤油为实验体系 ,溶质由水相萃取到有机相 ,在不同结构的单束螺旋状中空纤维膜器中研究了螺旋管纤维膜管内外流速以及螺旋管结构等因素对传质系数的影响 .实验结果表明 ,螺旋管中空纤维膜可以有效地提高中空纤维膜的传质特性 .随着管内流速的增加 ,传质系数将有很大提高 ,而管外流速对于传质系数的影响则较小 .至于螺旋结构的影响为 :随着螺旋内径的减小或者是螺旋螺距的减小 ,总传质系数相应地有很大提高 .最后得到了在本实验条件下计算总传质系数K的关联式     

中空纤维更新液膜传质性能的研究

研究了中空纤维更新液膜(HFRLM)技术的传质性能.以CuCl2水溶液-10%P204 煤油-盐酸为实验体系,研究结果表明,中空纤维更新液膜技术可以实现同级萃取-反萃,且总传质系数随料液相流速的增大而增大,在实验条件下,总传质系数受反萃相流速的影响较小.实验研究探讨了混合方式(料液与萃取剂混合和反萃剂与萃取剂混合)和体系分配系数对传质性能的影响.实验结果表明,由于相间分配系数的不同,总传质系数受混合方式的影响较大,以分配系数较大的一相与萃取相混合流经管程的方式对传质过程有利.     

低浓度醋酸水溶液的回收

通过三脂肪胺－煤油－正癸醇体系萃取低浓醋酸水溶液的实验，比较了萃取剂三种成分的不同酸比以及温度对分配系数的影响，确定了萃取操作的最佳萃取剂配比及适宜操作温度。通过静态混合器对萃取过程的强化及减压精馏回收萃取剂实验，验证了三脂肪胺－煤油－正癸醇体系萃取低浓醋酸的工业可行性。     

中空纤维更新液膜在己内酰胺精制中的应用

研究了中空纤维更新液膜技术用于己内酰胺精制时的传质性能,考察了两相流速、萃取剂用量对传质的影响,并与大块液膜技术以及萃取塔技术进行了对比。在实验范围内,中空纤维更新液膜过程总传质系数随两相流速的增大而增大,且壳程流速对传质的影响较大。中空纤维更新液膜过程传质通量可达大块液膜的1．5倍,总体积传质系数可达工业萃取塔的2．3倍,萃取剂用量相比于大块液膜、工业萃取塔大幅度降低,具有很大的应用潜力。     

乳化液膜萃取Cr(Ⅲ)的传质模型研究

采用经合理简化后的Ⅱ型渐进前沿性模型对DEHPA-Span80-液体石蜡-煤油乳化液膜体系萃取分离Cr(Ⅲ)的传质模型进行研究,此模型不仅考虑乳滴内、外扩散阻力、乳滴外界面反应,还同时考虑了乳液渗透溶胀和液膜破损效应。模型经过简化后,使用Matlab软件绘制曲线与实验结果进行对比。结果表明:模型与实际情况较为符合,在该传质过程中,传质阻力主要为乳滴内、外扩散阻力、乳滴外界面反应,且乳液渗透溶胀作用对液膜萃取影响比较大,膜破损阻力可忽略不计。     

溶胀对中空纤维膜萃取器中的流动和传质性能的影响

溶胀是中空纤维膜萃取工业化必须要解决的关键问题之一。本文通过拍摄电镜照片，观察了溶胀前后中空纤维膜表面形态，孔隙率，膜孔径，膜孔道弯曲状况等微观结构的变化。结果表明，溶胀会使中空纤维膜孔隙率减小，膜孔径变小，弯曲因子增大，通过测量发现，溶胀后膜长度增加，而膜的内外径，膜厚基本不变。本文还研究了溶胀时间对中空纤维膜器中的流动及传质效果的影响，通过测量聚丙烯和聚砜中空纤维膜器管程和壳程的停留时间分布曲线表明，对于装填密度较高的膜器，溶胀时间对壳程和管程中的流动状况的影响可以忽略。此外，本文以正辛醇－苯胺－水为实验体系，在中空纤维膜器中进行了循环逆流传质实验。实验证明，由于溶胀使纤维膜阻增加，膜器的传质性能随时间的增加而下降。     

气体搅拌下微分萃取过程的传质及流体力学性能的研究

在装有静态分布器的萃取塔中，对有气体搅拌下的水，煤油（苯甲酸）萃取系统的滞液率，气含率和传质系数进行了实验研究，从而得出气体搅拌下传质更充分的结论，分析了滞液率，气含率和传质系数的影响因素及分布规律。     

Effect of swelling on mass transfer performance in membrane extraction

The membrane extraction experiments were performed with tributyl phosphate/acetic acid (HAc)/water, n-butanol/HAc/water and 20% Alamine (in kerosene); HAc; and water as working systems. HAc was transferred from the aqueous phase to the organic phase. The effect of flat membranes swelling on mass transfer was studied. The membranes were microporous polysulfone and microporous polytetrafluoroethylene. The overall mass transfer coefficients based on the water phase were calculated and compared between nonswollen and swollen membranes. The experimental results show that the physical structure of the flat membranes used in our experiments was changed if soaked by organic solvents; however, change in thickness was not found. The overall mass transfer coefficients clearly were decreased after the flat membranes were swollen. The most likely reason is that the mass transfer resistance was increased because of the change of the membrane structure. The results also show that it is better to choose a hydrophilic membrane to reach high mass transfer performance when the equilibrium constant is very low. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1555–1561, 1999     

聚四氟乙烯膜气体吸收数学模型和孔隙率的影响

膜吸收是将膜分离与传统的吸收技术相结合的一种新型分离技术。在这些过程中经常使用多孔膜,多孔膜对过程的传质性能有一定的影响。对不同孔隙率的微孔聚四氟乙烯(PTFE)疏水性平板膜的膜气体吸收过程中液相传质性能进行了实验研究。当采用去离子水-CO2吸收体系时,多孔膜的孔隙率对液相传质性能没有影响;当采用NaOH水溶液-CO2吸收体系时,多孔膜的孔隙率对液相传质性能有明显的影响。在相同流速下,孔隙率大的膜液相传质系数高于孔隙率小的膜。以双膜理论为指导,建立了多孔膜气体吸收过程中液相传质模型。用该模型描述多孔膜孔隙率对液相传质系数的影响,其结果与实验数据具有良好的一致性。     

Performance of hollow fiber supported liquid membrane on the extraction of mercury(II) ions

The extraction and recovery or stripping of mercury ions from chloride media using microporous hydrophobic hollow fiber supported liquid membranes (HFSLM) has been studied. Tri-n-octylamine (TOA) dissolved in kerosene was used as an extractant. Sodium hydroxide was used as a stripping solution. The transport system was studied as a function of several variables: the concentration of hydrochloric acid in the feed solution, the concentration of TOA in the liquid membrane, the concentration of sodium hydroxide in the stripping solution, the concentration of mercury ions in the feed solution and the flow rates of both feed and stripping solutions. The results indicated that the maximum percentages of the extraction and recovery of mercury ions of 100% and 97% were achieved at the concentration of hydrochloric acid in the feed solution of 0.1 mol/l, the concentration of TOA at 3% v/v, the concentration of sodium hydroxide at 0.5 mol/l and the flow rates of the feed and stripping solutions of 100 ml/min. However, the concentration of mercury ions from 1–100 ppm in the feed solution had no effect on the percentages of extraction and recovery of mercury ions. Thus, these results have identified that the hollow fiber supported liquid membrane process has high efficiency on both the extraction and recovery of mercury (II) ions. Moreover, the mass transfer coefficients of the aqueous phase (k _i ) and membrane or organic phase (k _m ) were calculated. The mass transfer coefficients of the aqueous phase and organic phase are 0.42 and 1.67 cm/s, respectively. The mass transfer coefficient of the organic phase is higher than that of the aqueous phase. Therefore, the mass transfer controlling step is the diffusion of the mercury ions through the film layer between the feed solution and the liquid membrane.     

膜萃取过程的传质特性研究

膜萃取是一种新型的分离技术。本文在中空纤维膜器中研究了膜萃取过程的传质特性。通过四种不同体系的实验,求取了基于水相的总传质系数,提出了求算膜萃取过程中各分传质系数k_(?)、k_(?)、k_(?)的半经验关联式。研究表明,减小膜阻可以强化膜萃取过程,提高过程的总传质系数.比较和分析膜萃取过程中各部分传质阻力,可以看出,对于萃取相平衡常数m1的体系应选用疏水膜器,对于m1体系则应选用亲水膜器。     

Computational Simulation of Mass Transfer in Molecular Separation Using Microporous Polymeric Membranes

Computational simulation was conducted to predict mass‐transfer phenomenon in the molecular separation of solute using microporous membrane contactors. Both diffusional and convectional mass‐transfer mechanisms were considered. The membrane system was a hollow‐fiber contactor in which an aqueous phase containing an organic compound was contacted with an organic phase for extractive separation of the solute. Benzoic acid was used as the solute. The main focus was on understanding the mass transfer of solute in the process. The concentration equation for the solute was solved numerically using a computational fluid dynamics approach. It was found that the model can predict the solute transport from the aqueous phase to the organic phase and can be used as a predictive model for process understanding.     

Simultaneous Transport and Separation of Cu(II) and Zn(II) in Cu-Zn-Co Sulfate Solution by Double Strip Dispersion Hybrid Liquid Membrane (SDHLM)

A double strip dispersion hybrid liquid membrane (SDHLM) was successfully used in the simultaneous extraction and separation of Cu(II), Zn(II), and Co(II) from Cu-Zn-Co dilute feed phase. In the double SDHLM system, Acorga M5640-loaded membrane was placed between the 1st and the 2nd compartment, whereas the mono(2-ethylhexyl) 2-ethylhexyl phosphonate [HEH(EHP)]-loaded membrane was placed between the 1st and the 3rd compartment of the transport cell. The feed solution was filled in the central feed compartment(1st compartment) of the transport cell. The effect of the different experimental variables on separation was examined. The optimum separation conditions were summarized.

An analysis of mass transfer resistances in the double SDHLM system shows that the mass transfer resistance for the diffusion of Zn(II) ions in the microporous membrane phase is dominant and the mass transfer resistances for the diffusion of copper (II) ions in the aqueous boundary layer and in the microporous membrane phase are dominant in comparison with the overall mass transfer resistance. The experiments verify that the double strip dispersion hybrid liquid membrane (SDHLM) possesses the nonequlibrium mass transfer characteristic.     

Phenol recovery with tributyl phosphate in a hollow fiber membrane contactor: Experimental and model analysis

The extraction and stripping of phenol using a solution of tributyl phosphate in kerosene in a hydrophobic polypropylene hollow fiber membrane contactor has been studied. The effect of the aqueous and the organic phase flow rates on the overall mass transfer coefficient for both extraction and stripping steps was investigated. Experimental values of the overall mass transfer coefficient were determined and compared with predicted values from the resistance in series model. Results showed that the overall mass transfer coefficients for extraction were about one order of magnitude greater than those measured during the stripping process. The experimental values were in good agreement with the predicted values for the extraction module. However, the predicted values were slightly overestimated for the stripping module. The individual mass transfer resistances were analyzed and the rate-controlling steps of mass transfer were also identified in both extraction and stripping modules. The major resistance in extraction and stripping was in the aqueous phase and in the membrane phase, respectively.     

Analysis of Extraction of Cu(II) by Strip Dispersion Hybrid Liquid Membrane (SDHLM) using PMBP as Carrier

A liquid membrane system, denoted a strip dispersion hybrid liquid membrane (SDHLM) containing 1‐phenyl‐3‐methyl‐4‐benzoyl‐pyrazolone –5 as carrier in xylene, was reported for the transport and separation of Cu(II) from Zn (II) ions. The effects of various factors on the transport of copper(II) ions through SDHLM were systematically investigated by orthogonal tests. The optimum transport conditions of copper ions were summarized. In the overall mass transfer process the mass transfer resistance due to the aqueous boundary layer diffusion and diffusion in the microporous membrane is dominant. The accumulation of the Cu(II)‐carrier coordination compound in the membrane shows that the transfer in SDHLM possesses the characteristic of nonequlibrium mass transfer in this study. The rheologic experiments verified that the organic phase in the SDHLM system was the non‐Newtonian fluid and the organic phase after transport of 6 hr was a system of thixotropy in our experimental conditions. The lag ring experiments proved that the thixotropy of the organic phase in the SDHLM system was relevant to the composition of the membrane. In the experimental comparison of two types of liquid membrane, SDHLM has superiority over SLM in respect of transport flux, permeability coefficient, recovery percentage or concentration of solute in the stripping solution, efficiency of uphill transport, loss of membrane solution, and the separation efficiency of the membrane.     

膜接触器及其相关过程在废水处理中的应用

膜接触器是一种通过膜作为两相之间的分离界面而实现相间传质的新型杂化膜过程,具体应用形式包括膜蒸馏、膜萃取、膜吸收、膜结构填料等.膜接触器使用微孔中空纤维膜将两流体分隔开,膜孔为两流体之间提供传质的场所.与传统接触分离器相比,新兴的膜接触器拥有分离效率高、工作范围宽、两相流速可单独控制以及结构紧凑等诸多独特的优点.文章着重于膜接触器及其相关过程在废水处理领域的最新研究成果和进展,具体分析比较了上述几种膜接触器的结构、工作原理和操作特点,充分展示了膜接触器在废水处理以及化工、医药、食品等领域特种分离中的广阔应用前景.