采用浅床技术测定亚铁氰化钛钾交换Cs+的传质特性

采用浅床技术分别研究了料液浓度、操作温度以及料液流速对用亚铁氰化钛钾无机离子交换剂从硝酸铯溶液中交换Cs+的总传质系数的影响.结果表明,随着料液浓度的上升,总传质系数变化不大,仅在q(交换剂相Cs+浓度)较高时呈微弱的下降趋势.在实验范围内,随着操作温度的升高,总传质系数相应升高.料液流速对亚铁氰化钛钾交换Cs+的总传质系数的影响最大,其影响分为两个阶段当q＜0.25mmol/ml时,对一定的料液流速,总传质系数随着q值增加而较快下降;对一定的q值,总传质系数随着料液流速增加而增加.当q≥0.25mmol/ml时,时一定的料液流速,总传质系数随着q值增加缓慢下降;对一定的q值,不同料液流速下的总传质系数几乎没有区别.总之,当q值较小时,传质过程由液膜扩散和交换剂粒内扩散共同控制;当q值较大时,液膜扩散阻力相对于交换剂粒内扩散阻力要小得多,传质过程由交换剂粒内扩散控制.     

T形微通道中气泡分散流的传质性能

在T形微通道中,以错流剪切的分散方式实现了微米级分散气泡的制备,并以NaOH水溶液吸收CO2为对象,考察了气．液微分散体系的分散规律和传质性能．通过考察两相流速对气泡分散尺寸的影响,建立了预测气泡形成尺寸的数学模型．根据气泡的初始分散尺寸、流动阶段的体积变化以及传质完成后的尺寸,首次测定和区分了气泡形成阶段和运动阶段的传质量,建立了原位测定气泡分散流传质系数札的方法,并考察了两相流量对札的影响．结果表明,由于微通道中气泡的形成时间很短,形成阶段的传质量在总传质量中所占的比例很低．气泡分散流的传质系数主要受液相流量的影响,气相流量的影响基本可以忽略．基于实验结果,建立了计算传质系数鼠的无因次准数关联,计算结果与实验结果符合良好．     

固体粒子对板式膜吸收过程的传质强化

分别采用纯CO2-去离子水和不同浓度的NaOH溶液为实验体系,在板式膜器中研究了第三相固体粒子对膜吸收过程传质效果的影响．分别考察了在不同粒子种类、搅拌转速、传质体系、化学反应强度、膜孔隙率等因素下固体粒子对传质强化的影响．结果表明,随着粒子固含率的增大,传质系数和增强因子均有所提高,当粒子固含率增大到一定范围后,传质系数和增强因子的变化趋于平缓．在固含率一定的条件下,不同种类的固体粒子对膜吸收过程的强化效果随着固体粒子密度的增加而减小．传质系数随着搅拌转速的增大而增大,但高搅拌转速下固体粒子的强化作用减弱．膜吸收过程的传质系数和增强因子随着化学反应强度的增强而增加．随着粒子固含率的增大,不同膜孔隙率对传质效果的差异减小,且孔隙率越小,固体粒子对膜吸收传质过程的强化效果越好．其中,对于纯CO2-去离子水体系,当孔隙率为20％,粒子固含率为1．5gL^（-1）时,固体粒子的加入可使传质系数提高1．45倍,增强因子可达2．45．     

膜供氧催化氧化处理太空舱冷凝废水研究

采用膜供氧催化氧化反应器处理太空舱冷凝废水。以乙醇为目标污染物,研究了膜供氧催化氧化反应器对其的处理效果,并考察了催化反应对膜传质模型的影响。结果表明,随着停留时间的增加,乙醇的去除率增大,中间产物乙酸的生成率减少。当废水流量为0.5mL·min-1,气室压力为2kPa时,乙醇的去除率可达86.1%,其中81.4%完全氧化,4.7%转化成乙酸。基于传质模型对实验结果分析表明,催化反应有利于提高膜供氧总传质系数,当流量为0.5mL·min-1时,与无催化反应条件相比,氧总传质系数提高11.8倍。停留时间的增加也有利于提高膜供氧传质系数。结果表明,膜供氧催化氧化反应器可高效降解冷凝废水中的乙醇,在太空舱冷凝废水处理中有潜在的应用价值。     

中空纤维膜萃取分离混合稀土中的钍

通过中空纤维膜逆流萃取，研究了伯胺Ｎ１９２３对Ｔｈ４＋和ＲＥ３＋的萃取分离过程。测定了水相料液硫酸浓度、水相与油相流量对传质系数的影响，并对包头矿硫酸分解浸出液进行中空纤维膜萃取实验。结果表明，Ｔｈ４＋的传质系数受水相流量影响，与酸度及油相流量无关，总传质速率受水相临界层传质步骤控制。ＲＥ３＋的传质系数不受水相流量影响，油相流量影响很小，但受硫酸浓度的影响，总传质速率受萃取反应速率控制。根据传质速率的不同，对包头矿硫酸浸出液进行萃取分离，在８ｈ内Ｔｈ４＋可基本萃取完全，而ＲＥ３＋及Ｆｅ３＋基本不被萃取，故可在密封条件下分离钍。     

H2和CO在甲醇和甲酸甲酯中的体积传质系数的研究

利用一立升的高压搅拌釜，在不同的温度（２９６～３７３Ｋ）、气体压力（１．０～５．０ＭＰａ）下，研究了Ｈ_２、ＣＯ在甲醇和甲酸甲酯中的体积传质系数（ｋ１ａ），并对Ｈ_２－甲醇体系，研究了不同搅拌速度（８００～１２００ｒ／ｍｉｎ）和颗粒浓度（０～１５Ｗ％）对Ｈ２在甲醇中的体积传质系数的影响。实验中发现：气体在两种液体介质中的体积传质系数均随温度的升高而增加，随气体分压的增加而增加。在同一种液体介质中，Ｈ_２的体积传质系数高于ＣＯ，对于同一种气体，在甲酸甲酯中的传质系数高于甲醇中的传质系数。对Ｈ_２－甲醇体系的研究结果表明，提高搅拌速度可以增加Ｈ_２的体积传质系数，但颗粒浓度的增加则降低Ｈ_２在甲醇中的体积传质系数。     

氢气在松脂和松香中的体积传质系数

高压搅拌釜和计算机数据采集系统，在温度373 K～573 K，压力2.0 MPa～10.0 MPa，搅拌转速600 r/min的实验条件下，根据气体等容吸收降压原理，测定了氢气在松脂和松香中的体积传质系数，并建立了体积传质系数与温度、压力的关联式，为松脂和松香催化加氢反应动力学的研究提供了基础数据。考察了温度、压力对体积传质系数的影响，结果表明体积传质系数随温度和压力的升高而增加。在计算体积传质系数过程中，微分法与积分法二者之间平均绝对偏差为：松脂4.74×10－4，松香1.21×10－4。     

液相色谱技术测定葡萄糖果糖在Ca型吸附剂上相平衡常数和总传质系数

]考虑轴向扩散的影响,导出液相色谱技术测定吸附相平衡常数和总数传质系数参数估值模型,测定葡萄糖果糖吸附相平衡常数和总传质系数,研究流速、温度对这些参数的影响。获得理论计算与色谱分离实验流出曲线相吻合结果。     

连续环状色谱分离木糖—山梨糖混合溶液的研究──轴向扩散系数和总传质系数的辨识

本文提出了连续环状色谱分离过程的参数辨识方法，包括其轴向扩散系数的辨识模型，以惰性物ＣａＣｌ２作示踪剂，００１×７树脂为填料，采用扰动－应答法技术在环状色谱床中测定轴向扩散系数。考虑轴向扩散的作用，建立了线性吸附平衡体系的相平衡常数及总传质系数的辨识模型，并对木糖──山梨糖体系，采用扰动－应答技术测定相平衡常数及总传质系数。考察了操作因素对轴向扩散系数与总传质系数的影响规律。结果表明，流速增加，轴向扩散系数加大，环状色谱床中的流动明显地偏离理想活塞流；流速增加，总传质系数也相应增大。     

湿润率对疏水性膜接触器传质性能的影响

根据双膜理论提出了疏水性膜湿润机理,关联了阻力层方程、Laplace方程和膜孔径分布函数,建立了新型传质数学模型,采用PP疏水性微孔膜、水和MDEA(N-甲基二乙醇胺)水溶液为吸收剂,研究了膜接触器吸收CO₂传质过程,考察了压差、表面张力和温度等因素所产生的湿润率对传质性能的影响.结果表明,用新型模型能较准确地预测湿润率对传质系数的影响,模型值与实验值符合较好;压差、表面张力和温度对湿润率影响较大,是膜接触器传质过程需要考虑的因素.     

中空纤维致密膜基吸收CO2传质过程

研究了硅橡胶/聚砜中空纤维致密膜基吸收CO2的传质机理,考察了吸收剂种类(NaOH,MEA,DEA和TEA)、NaOH浓度、吸收剂流速、吸收剂压力和气相压力对CO2传质通量及传质速率的影响.其中,用2×103mol/m3NaOH作吸收剂时,聚合物膜传质为控制步骤,其传质效率与膜自然渗透相近.     

铈(Ⅳ)与RE(Ⅲ)的中空纤维膜基萃取分离

将中空纤维膜用于膜基萃取分离是７０年代开发的新分离技术,对金属离子的萃取分离［１～４］、有机有害物质的提取［５～７］及生物发酵产品和生物活性物质的提纯［８］均有报道．由于固体膜的相分离作用,中空纤维膜基萃取可实现非分散性分离操作,避免了液相萃取中液泛...     

聚偏氟乙烯中空纤维膜器对钐传质性能的影响

以Ｐ５０７－煤油ＨＣｌ－Ｓｍ为实验体系,在两种聚偏氟乙烯中空纤维膜器中研究了溶胀性能、反萃酸度对基于水相的总传质系数及中空纤维膜孔径的影响,考察了料液酸度、萃取剂浓度、钐离子浓度与萃取速率的关系。获得了相应的反应级数。根据界面反应动力学,得到了速率常数值和动力学方程。     

Racemic ofloxacin separation by supported-liquid membrane extraction with two organic phases

As the relation of chirality and activities of drugs is researched deeply, people become to re-alize the clinic importance of chirality. The different enantiomers of a drug can have vastly differ-ent pharmacological activities, pharmacokinetic processes and toxicity[1,2]. The most well-docu- mented example is that of the drug substance thalidomide. Bitter lessons and scientific research promote the interest in single-enantiomer drugs, so the potential of the chiral drug market is enormous[3]. …     

Membrane extraction for separation of copper cations from acid solution using polypropylene hollow fibre membrane

The membrane extraction of copper ions was carried out using hydrophobic poly(propylene) (PP) hollow fiber membrane modules and kerosene solutions containing organic extractant. The influences of different extractant on the extraction yield, mass transfer performance and mass transfer mechanism were studied. Compared with 2‐ethylhexyl phosphoric acid (2EHPA) and 2‐methyl‐5‐sulpho benzaldoxime (2M5SB), di‐(2‐ethylhexyl)phosphoric acid (D2EHPA) extractant system with high distribution coefficient exhibited higher extraction yield of 99.7%. The extraction equilibrium time, the final extraction yield and the total mass transfer coefficient were independent of the flow rates of two phases. The extraction equilibrium time and the final extraction yield at different flow rates of two phases were 80 min and near 99.5%, respectively. A mass transfer model of a complexation reaction describing the overall mass transfer resistance was controlled by interfacial reactions rather than the aqueous and organic boundary layer which could explain the effect of flow rate on the final extraction yield and the total mass transfer coefficient. This model showed that the mass transfer resistance and mass transfer coefficient were independent of Cu²⁺ when copper ion concentration was more than 0.06 g/L. However, when copper concentration was less than 0.06 g/l, the mass transfer resistance increased as Cu²⁺ concentration decreased, and the mass transfer coefficient decreased as Cu²⁺ concentration decreased. Extractant entrainment in the aqueous phase and membrane fouling were investigated primarily. It was found that the solvent entrainment could reduce to 10 ppm much lower than 200 ppm of the classic liquid–liquid extraction, and that the cleaning of contaminated membranes was not complete. However, it can be still concluded from this research that the membrane extraction in PP hollow fibre with D2EHPA extractant would be an effective and promising processing means for Cu²⁺ separation from aqueous solution. Copyright © 2005 John Wiley & Sons, Ltd.     

Extraction of hydroxyaromatic compounds in river water by liquid-liquid-liquid microextraction with automated movement of the acceptor and the donor phase

Liquid-liquid-liquid microextraction with automated movement of the acceptor and the donor phase technique is described for the extraction of six hydroxyaromatic compounds in river water using a disposable and ready to use hollow fiber. Separation and quantitative analyses were performed using LC with UV detection at 254 nm. Analytes were extracted from the acidified sample solution (donor phase) into the organic solvent impregnated in the pores of the hollow fiber and then back extracted into the alkaline solution (acceptor phase) inside the lumen of the hollow fiber. The fiber was held by a conventional 10 microL LC syringe. The acceptor phase was sandwitched between the plunger and a small volume of the organic solvent (microcap). The acceptor solution was repeatedly moved in and out of the hollow fiber using a syringe pump. This movement provides a fresh acceptor phase to come in contact with the organic phase and thus enhancing extraction kinetics thereby leading to the improvement in enrichment of the analytes. The microcap separates the acceptor phase and the donor phase in addition to being partially responsible for mass transfer of the analytes from the donor solution to the acceptor solution. Under stirring, a fresh donor phase will enter through the open end of the fiber that will also contribute to the mass transfer. Various parameters affecting the extraction efficiency viz type of organic solvent, extraction time, stirring speed, effect of sodium chloride, and concentration of donor and acceptor phases were studied. RSD (3.9-5.6%), correlation coefficient (0.995-0.997), detection limit (2.0-51.2 ng/mL), enrichment factor (339-630), relative recovery (93.2-97.9%), and absolute recovery (33.9-63.0%) have also been investigated. The developed method was applied for the analysis of river water.     

Extraction of Ce~(4+) from Tervalent Lanthanide with Immobilized Interface in a Microporous Hollow Fiber

中空纤维膜（ＭＨＦ）法研究了Ｃｅ４＋和三价稀土的溶剂萃取．结果表明Ｃｅ４＋的传质系数是Ｃｅ３＋和Ｌａ３＋的１０倍以上．Ｃｅ４＋的传质速度受水相临界层中扩散速度控制，ＲＥ３＋的传质速度受膜内扩散控制．Ｃｅ４＋能够从三价稀土中有效地分离．     

Shell-side mass transfer of hollow fibre modules in osmotic distillation process

The effect of packing density of hollow fibre modules on mass transfer in the shell side of osmotic distillation process was studied. The osmotic distillation experiments were carried out with several modules of the packing densities ranging from 30.6 to 61.2%. It was found that the Reynolds number was a function of packing density and packing density affected mass transfer performance. The shell-side mass transfer coefficient increased with the brine velocity. The membrane permeability can be predicted from the experimental flux at the maximum brine velocity. The mass transfer correlation was proposed in order to determine the shell-side mass transfer coefficient in the randomly packed modules for osmotic distillation process. The empirical correlation proposed was fitted to the experimental results and it was found that the mass transfer coefficients calculated from the proposed correlation were in good agreement with those from the experimental data. Comparison of the results obtained from the proposed correlation with other correlations in the literature was discussed.     

Absorption of CO2 in a transverse flow hollow fiber membrane module having a few wraps of the fiber mat

An experimental study of gas-liquid contacting was conducted to determine the mass-transfer performance characteristics of hollow fiber devices that employ transverse liquid flow over microporous hydrophobic fibers present in a mat wrapped around a central feeder tube. Gas flow was through the fiber lumen; water was employed to absorb CO₂ from pure CO₂ and from a mixture of CO₂N₂. The results are characteristics of the local crossflow mass transfer due to the limited number of wraps of fiber layers. A correlation for mass-transfer coefficient was developed and compared with correlations from the literature.