一种用于从水中分离挥发性有机化合物的疏水性渗透汽化中空纤维复合膜

研制出一种名为VOC-SEP200新型中空纤维疏水性复合膜，并考察了这种复合膜从水中分离BTEX(苯、甲苯、乙苯和二甲苯)的性能．这4种芳香碳氢化合物是工业有机废水中的一组有代表性的污染物，本研究的最终目的是想从现实的工业废水中回收这些化合物．采用料液在纤维中孔流动的方式，系统考察了进料液流速、操作压力、温度和进料液浓度对膜分离效率及膜性能的影响．结果显示，随着进料液流速的提高，BTEX的通量随之增大．这是由于随着进料液流速的提高，浓度极化的影响会减少，同时BTEX和水的分离因子会有显著增大．结果还显示，膜的性能随膜横向的驱动力降低而提高，其最佳的渗透压范围是10．7～13．3kPa(即80～100mmHg)，此时BTEX通量达到最大平稳值，同时水的通量最小．提高渗透压可减少操作费用，同时可增强分离效果，和预期的情况一样，BTEX和水的渗透通量都随着温度和进料浓度的提高而增大，但再进一步提高浓度和温度，则对水通量不产生影响．水通量在初始阶段的增加可以归因于膜的溶胀，水通量不再随温度和浓度的进一步升高而增加，可以归因于水分子的聚集与膜的溶胀达到了平衡，     

Electrochemically-aided membrane separation and catalytic processes

Electrochemically driven membrane separations and catalytic processes are interesting research areas which have, to date, received relatively little attention. Research into electrically-aided membrane separation and catalytic processes is currently being carried out in South Africa. The research objective is the development and characterisation of novel composite materials based on solid polyelectrolytes (SPE), containing nanoparticles of catalytically active metals, such as Pt, Ir or Pd, distributed within the polymeric matrices. An example of such an SPE matrix is a perfluorinated ion-exchange membrane. The novel composite materials (in fact, membranes) are both ionically and electronically conductive due to the presence of the metal nanoparticles. The application of potentials to conducting membranes results in the enhancement of catalytic activity as well as the selectivity of separations. The membranes based on SPE can be used for the catalytic processing of petrochemical mixtures, water treatment (disinfection, nitrate removal, etc.), oxygen, hydrogen and ozone generation, and electrically enhanced gas and vapour separations. In this paper Dr Dmitri Bessarabov briefly outlines the current status of the research, available technology and discusses challenges and possible applications.     

Nonfoaming adsorptive bubble separation processes

Two nonfoaming separations, bubble fractionation and solvent sublation, are reviewed. These unit operations are interfacial (gas bubble-liquid) separation techniques that have significant potential for the removal of several metal ions and hydrophobic organic compounds of environmental significance from aqueous solutions. Experimental and theoretical work on the two processes relating the effects of process variables are summarized. The underlying mechanisms of the two processes are identical although solvent sublation is found to have significant advantages over bubble fractionation, air stripping, and the related process of solvent extraction. Specifically, sublation can achieve a greater degree of removal than extraction, can remove both volatile and nonvolatile compounds, unlike air stripping, and has less sensitivity to axial dispersion than bubble fractionation. The potential use of these processes for large-scale separations is examined; the limitations and need for further work are clearly evident. Questions of scale-up, bubble generation, and reduction of axial dispersion all require further investigation.     

Workshop on advanced separation processes

An innovative and state-of-the-art workshop on advanced separation processes was held at Manhattan College, Riverdale, New York, USA, from 12–21 July 1993. This workshop was one of the many excellent programmes supported by the US National Science Foundation's Undergraduate Faculty Enhancement Programme.     

Membrane separation processes tackle textile waste-water treatment

This article briefly considers several ways of treating different streams that are generated by textile manufacturing processes, using techniques which are based on membrane separation technology.     

Modelling material separation processes in bulk recycling

Increasing environmental concerns about the disposal of mass produced products have resulted in efforts to recover value from components and materials before discarding such products. Methods include incineration, disassembly or de-manufacturing and bulk recycling. This paper investigates several cases of the problem of selecting the best sequence for recovery of materials by bulk recycling. A solution procedure for determining the optimal sequence for isolating all target materials present in a given batch based on dynamic programming is presented. A modification for targeting specific materials in a batch is discussed. Additional constraints arising from the operation of such facilities are also discussed. The general problem of target material identification is presented and a procedure for selecting a profitable target material mix, along with a numerical illustration, is documented. Finally, the integrated consideration of bulk recycling and disassembly for evaluating product disposal costs is presented.     

Calculation of diffusion separation processes in gas mixtures

The selective action of various types of force fields on isotopic gas mixtures is considered using the multicomponent hydrodynamic approximation. It is shown that it is possible to indirectly estimate the intensity of mutual diffusion and the separation effect in all cases of practical importance.Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 48, No. 4, pp. 628–632, April, 1985.     

类甜菜碱药液的膜分离工艺研究

研究开发对类甜菜碱水溶液常规过滤除杂、电渗析(ED)脱盐,然后纳滤(NF)浓缩的处理工艺．结果表明,在ED运行20～30min后,类甜菜碱水溶液的脱盐率高达99．4％,NF水通量随操作压力升高而增加,在较低操作压力时稳定在35～40L／(m^2．h)之间．浓缩倍数增加,NF通量迅速下降、ED脱盐后的药液淡水和NF膜的渗透液经紫外分光光度计480nm波长检测的吸光度值都为零,表明分离工艺合理,选用的膜对类甜菜碱具有优良的截留性能。     

Recent advances in the simultaneous bioreaction and product separation processes

Recent advances in the development of processes of simultaneous bioreaction and product separation are reviewed and presented. Such processes that, in principle, may be realized by combining bioreaction with various separation methods such as adsorption, gas stripping, extraction, membrane separation, and so forth have the advantages of enabling the bioreaction to be conducted with high substrate concentration, diminishing the effect of product inhibition, reducing the energy requirement for separation and enhancing bioreaction rates. Comments concerning important future studies in this area are also offered as part of the presentation.     

Pyrometallurgical processes for the separation of hafnium from zirconium

The paper reviews the various pyrometallurgical processes developed for the separation of hafnium from zirconium and also discusses the criteria for the selection of the process to be adopted for the preparation of nuclear grade zirconium in the country.     

膜分离技术在抗生素提炼过程中的应用

膜分离过程是一种选择性高,操作简单,能耗低的纯物理分离技术,已在各工业领域和科学研究中得到广泛的应用,文章对膜分离技术在抗生素提炼领域的技术进展进行了较全面的综述。     

林可霉素发酵液膜分离工艺条件的研究

对影响林可霉素发酵液膜分离性能的主要工艺参数及对后序萃取工艺的影响进行了研究,确定的最佳膜分离工艺为:采用螺旋卷式膜组件,进料温度控制在30℃以下;超滤压力0.2 MPa、纳滤压力1.0 MPa;超滤膜面流速300 L/h,纳滤膜面流速90 L/h;超滤浓缩倍数 3.0,纳滤浓缩倍数3.0-4.0之间效果最好.林可霉素板框滤液经超滤、纳滤后再萃取,可使萃取级数由9级减少到4级,混合醇用量减少到原来的1/3,林可霉素收率比原来提高8.9%.     

Life cycle assessment of membrane-based carbon capture and storage

Many investigations have conducted life cycle assessments (LCA) of the most commonly discussed routes of carbon capture and storage (CCS): post-combustion with amine wash separation; oxyfuel using cryogenic air separation and pre-combustion by integrated gasification combined cycle (IGCC) using physical separation. A research alliance developed corresponding separation systems using different types of membranes to allow a more energy efficient separation process: polyactive polymeric membranes for post-combustion, ceramic membranes for oxyfuel and metallic membranes for IGCC separation. By conducting an LCA, the study examines the actual greenhouse gas emissions and other environmental impacts of the new membrane separation technologies, together with concepts implementing the more common technologies. The reference systems represent today’s state-of-the-art supercritical coal fired power plant in Germany, together with a more advanced ultra-supercritical plant operating at 700 °C without CO₂ capture. The results demonstrate that among the three reference power plants the IGCC is the superior concept due to the highest efficiency. Regarding climate change, the IGCC power plants with CO₂ capture are still the best concepts. When other environmental impacts are considered, the capture technologies are inferior. The membrane concepts show the overall better results in comparison to the conventional capture technologies. The environmental impacts for membrane applications add a new range of findings to the field of CCS LCAs. Now the results for several different approaches can be compared directly for the first time.     

液膜分离技术进展

简要回顾了液膜分离过程的发展史，分析了乳化液膜和支撑液膜的特点及其存在的问题。介绍了近年来各国学者在改进液膜稳定性方面所作的努力，并展望了液膜工业化的前景．     

下游处理对PLGA微球分离制备的影响

为获得球形度较高且表面光滑的PLGA微球,提高微球的生物相容性,考察了直接冷冻干燥法等不同的下游处理过程对微球分离制备的影响,采用扫描电镜和原子力显微镜对产品进行分析.研究表明:直接冷冻干燥法(一步法)可获得镶嵌有微球的纤维状网络结构,是一种构建与微粒结合有关的组织工程支架材料的新方法;过滤法采用的时间长,不利于酶等物质活性的保持,同时也不易除去PVA;离心处理方法对获取球形度较高且表面光滑的PLGA微球更为有效,而超声分散对微球的形态结构造成影响.     

Single wire model of high gradient magnetic separation processes I

A rate equation is being developed to model the buildup of single-sized, weakly magnetic particles on a single ferromagnetic cylindrical wire. The equation relates the rate of buildup on the wire to the fraction of the incoming particles that are captured and the portion of the particles that are carried away by the fluid stream. The theoretical predictions and experimental results generally agree well for a range of field values, flow rates, and particle concentrations. A more accurate model of the collection process will enable development of more accurate models for arrays and entire filters.     

ATR-FT-IR membrane-based sensor for integrated microliquid-liquid extraction and detection

A novel straightforward membrane-based sensor, which uses attenuated total reflection Fourier transform infrared (ATR-FT-IR) spectroscopy has been developed. The flow cell designed permits the on-line microliquid-liquid extraction of the target analyte into a organic solvent layer (OSL), which was deposited on the ATR surface using a sequential injection manifold. The aqueous and organic phases are separated via a commercial hydrophobic membrane placed on the PTFE piece of the cell. The main advantage of the proposed device is that the OSL can be created and regenerated in a continuous manner using the automatic manifold without opening the cell. The analytes are enriched into the OSL after diffusion through the membrane, which excludes the typical absorption bands of water. In addition, the behavior of different organic solvents was evaluated in order to increase the applicability and versatility of the proposed system. Finally, the analytical performance of the design was established for the detection and quantitation of Triton X100 in water.     

聚醚砜-环氧树脂共混体系相分离过程的数值模拟

在热塑性聚醚砜（PES）增韧改性热固性环氧树脂复合材料的制备过程中,通过控制PES-环氧树脂树脂共混体系相分离过程实现共混物相结构的调控,能够明显改善热固性环氧基体树脂的冲击强度。考虑PES-环氧树脂共混体系在相分离过程中PES应力松弛现象以及环氧树脂固化反应现象,采用黏弹性模型描述微观相形态的具体演化路径,揭示了树脂共混体系相分离过程的机制及动力学过程,分析了PES含量、PES分子量大小、PES与环氧树脂的动力学不对称程度以及固化工艺条件等材料及工艺参数对共混体系相结构演变过程以及最终相形态的影响规律及程度,从而为优化PES-环氧树脂树脂共混体系的微观相结构打下基础。     

Membrane-based hybrid processes for high water recovery and selective inorganic pollutant separation

The removal of heavy metals (e.g. Pb(II), Cd(II), Cu(II), etc.) and oxyanions (e.g. nitrate, As(III, V), Cr(VI), etc.) is of immense interest for treatment of groundwater and other dilute aqueous systems. However, the presence of non-toxic components, such as hardness (Ca, Mg) and sulfate, can interfere with the separation of toxic species. For example, pressure-driven membrane processes, such as reverse osmosis (RO), have been limited for water treatment due to problems that these extraneous components cause with water recovery and ionic strength (osmotic pressure) of the retentate. In addition, nitrate rejection by RO is considerably lower than NaCl rejection, resulting in permeate concentrations that may be too high for groundwater recharging. Other separation systems that rely solely on sorption of toxic species (e.g. ion exchange resins) may not have sufficient selectivity for efficient use in the presence of competing ions. Hence, implementation of pressure-driven membrane separations and high capacity sorbents in hybrid processes shows much promise for remedying these difficulties. For example, selective separation of nitrate may be achieved by combining nanofiltration (NF) for sulfate removal, followed by RO or ion exchange for nitrate removal (see example 1). When small concentrations of toxic metals are present, the large retentate volumes of RO processes may be reduced by selective removal of toxic species with a high capacity sorbent, thus permitting disposal of a lower volume, non-toxic stream (see example 2). The use of microfiltration membrane-based sorbents containing multiple polymeric functional groups is a novel technique to achieve high metal sorption capacity under convective flow conditions. These sorbents are formed by the attachment of various polyamino acids (MW: 2500-10,000), such as polyaspartic acid (cation sorption), polyarginine (oxyanion sorption), and polycysteine (chelation exchange), directly on the membrane pore surfaces. Since these sorbents have also been found to have high selectivity over non-toxic metals, such as calcium, they are ideal candidates for hybrid processing with RO/NF.