关于反渗透、超滤过程中的浓差极化比及其表达式的研究

本文在膜的吸附-扩散分离模型的基础上讨论了浓差极化现象,得出了浓差极化比与溶质和膜表面相互作用的物化特性(K_A/K_B)有关的结论,给出了浓差极化比的理论公式。分析了溶质在膜表面优先吸附和受排斥情况下的浓差极化现象。     

圆平板反渗透膜浓差极化边界层内传质系数的关联

实验研究了ＮａＣｌ水溶液反渗透分离过程，关联了圆平板膜浓差极化边界层内溶质传质系数的准数方程；并用ＫＣｌ，Ｎａ２ＳＯ４水溶液的反渗透分离数据对准数方程进行了验证。     

液体分离膜过程中的浓差极化及其评价方法

膜的污染和劣化始终是制约膜技术发展的瓶颈之一．在液体分离膜过程中,浓差极化是产生膜污染的主要原因,因此减小浓差极化即可减轻膜污染．本文首先介绍了浓差极化现象和模型以及传质系数的求算,并且提出一种简单的实验方法测定膜过程的浓差极化程度,然后针对不同分子量的溶质体系对影响浓差极化程度的操作条件进行定量分析,包括操作压力和原料液循环流量,最后对如何减轻液体分离膜过程由浓差极化导致的膜污染给出几点建议．     

垫片法对正渗透过程中浓差极化的改善研究

在不增加能耗的前提下提出了一种简易的垫片法改善正渗透过程中出现的浓差极化现象.利用这种方法,在正渗透膜活性层朝向原料液的膜取向下,发现垫片安置在汲取液廊道贴紧膜的位置可以最好地减缓稀释内浓差极化,进而显著的提升正渗透的运行效果;此时,以0.5 mol/L的NaCl为原料液,而分别以1、2、4 mol/L的NaC1为汲取液进行批式实验,与未安置垫片的方式相比,水通量分别有2.94％,9.0％和12.5％的提升幅度;另外,还发现当将垫片放置在原料液廊道(远离膜)和汲取液廊道(贴紧膜)时,可以起到同时减缓浓缩外浓差极化(CECP)和稀释内浓差极化(DICP)的效果.     

电渗析过程中的浓差极化及水解离机理

分析了电渗析在运行过程中浓差的形成以及与水解离之间的关系，在此基础上，分析了V－I曲线以及其拐点所代表的物理意义。通过理论分析认为：“浓差极化”的实质是“电势极化”。实验测得的V－I曲线验证了理论V－I曲线的正确性。     

研究浓差极化和膜污染过程的方法与策略

简要综述了浓差极化和膜污染的研究方法和策略．利用超滤法处理印钞擦版废液实验说明研究思路和各种分析方法的应用．通过膜阻力模型实验,分析出各污染途径产生的阻力大小,讨论了应注意的问题．采用EDX,ICP,TOC,SEM,FTIR和MC对膜污染物、酸洗和碱洗液、清洗前后膜表面形貌分析鉴定,发现主要无机污染物是钙离子,主要有机污染物是磺化蓖麻油．模拟实验结果与上述结果一致,并引导出四步清洗方法,可对污染膜进行有效清洗;并发现对于严重污染的膜,采用三个以上清洗周期才能使膜通量得到完全恢复．最后提出一个浓差极化和膜污染的研究方法和策略框架图．     

对《电渗析过程中的浓差极化及水解离机理》一文有关错误的分析

在2005年第1期《膜科学与技术》杂志上我们已对孟洪等撰写的《电渗析过程中的浓差极化及水解离机理》一文提出质疑,并指出其错误所在．现在进一步对该文的错误进行分析．     

正渗透工艺用于微藻生物燃料脱水的研究进展

微藻作为第三代生物能源,在应对传统能源危机方面具有十分巨大的发展潜力。由于微藻脱水能耗巨大,导致后续的微藻生物燃料制备难以实现大规模商业化生产.针对此瓶颈问题,研究人员尝试采用正渗透工艺进行微藻脱水.基于近年来正渗透技术应用于微藻脱水的研究现状,综述了膜污染成因与控制、膜材料开发与膜结构优化、工艺节能增效等方面的研究进展,着重总结了在藻种、正渗透膜以及汲取液等明显影响微藻脱水性能因素方面的研究成果,并指出了未来采用正渗透技术进行微藻脱水的发展趋势.     

Nonstationary concentration polarization in laminar ultrafiltration in a plane channel

A semiintegral method of determination of concerntration polarization is suggested and specific features of the latter in laminar ultrafiltration in a plane channel are discussed.Academic Scientific Complex A. V. Luikov Heat and Mass Transfer Institute, Academy of Sciences of Belarus, Minsk. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 67, Nos. 1–2, pp. 103–107, July–August, 1994.     

Depolarization of surface-enhanced fluorescence: an approach to fluorescence polarization assays

Localized surface plasmons of metallic particles of subwavelength sizes strongly modify the spectral properties of nearby fluorophores. The enhanced radiative decay rate leads to high fluorescence efficiencies and decreased fluorescence lifetimes. In this report we show that metal-enhanced fluorescence generated by the presence of the silver islands on the glass substrate displays high depolarization. Intensities, lifetimes, and emission anisotropies of several fluorophore protein conjugates have been studied in the absence and presence of metallic nanostructures. Despite highly decreased lifetimes of about 10-fold and immobilization of conjugates on the solid substrate, the observed emission anisotropies for all fluorophores on the metal-enhanced substrate decreased 300-500% compared to that in solution. This observation implies a new generation of fluorescence polarization immunoassays with broad applications because of no restrictions to the lifetime of the probe and the size of labeled biomolecules. The changes in polarization are due to binding that occur on the bioactive surface localized near the metal particles.     

Bipolar electrode focusing: faradaic ion concentration polarization

Bipolar electrode (BPE) focusing locally enriches charged analytes in a microchannel along an electric field gradient that opposes a counter-flow. This electric field gradient forms at the boundary of an ion depletion zone generated by the BPE. Here, we demonstrate concentration enrichment of a fluorescent tracer by up to 500,000-fold. The use of a dual-channel microfluidic configuration, composed of two microchannels electrochemically connected by a BPE, enhances the rate of enrichment (up to 71-fold/s). Faradaic reactions at the ends of the BPE generate ion depletion and enrichment zones in the two, separated channels. This type of device is equivalent to previously reported micro/nanochannel junction arrangements used for ion concentration polarization, but it is experimentally more flexible and much simpler to construct.     

Continuous-flow biomolecule and cell concentrator by ion concentration polarization

We present a novel continuous-flow nanofluidic biomolecule/cell concentrator, utilizing the ion concentration polarization (ICP) phenomenon. The device has one main microchannel which bifurcates into two channels, one for a narrow, concentrated stream and the other for a wider but target-free stream. A nanojunction [cation-selective material (Nafion)] is patterned along the tilted concentrated channel. Application of an electric field generates the ICP zone near the nanojunction so that biomolecules and cells are guided into the narrow, concentrated channel by hydrodynamic force. Once biomolecules from the main channel are continuously streamed out to the concentrated channel, one can achieve a continuous flow of the same sample solution but with higher concentrations up to 100-fold. By controlling hydrodynamic resistance of the main and concentrated channel, the concentration factors can be adjusted. We demonstrated the continuous-flow concentration with various targets, such as bacteria [fluorescein sodium salt, recombinant green fluorescence protein (rGFP), red blood cells (RBCs), and Escherichia coli ( E. coli )]. Specially, fluorescein isothiocyanate (FITC)-conjugated lectin from Lens culinaris (lentil) (FITC-lectin) was tested on the different buffer conditions to clarify the effect of polarities of the target sample. This system is ideally suited for a generic concentration front-end for a wide variety of biosensors, with minimal integration-related complications.     

Determining steelmaking aim chemistry utilizing an iterative and knowledge-based approach

Development of knowledge-based systems for material design is a complex task, due to the interelationship of many factors in the steelmaking process. In addition, design specifications vary frequently and materials design knowledge is held in a largely intuitive undefined format. This paper discusses the first stage of a material design system which deals with the determination of the steelmaking aim chemistry. If an attempt is made to design aim chemistry based on the mathematical approach of utilizing the empirical models between various design parameters it would result in an unrealistic design because relationships between various design parameters are not always linear. Therefore applying the knowledge-based approach along with the mathematical approach to deal with this complex task is inevitable. The approach put forward in this paper is a hybrid one, where the knowledge base is applied at every stage of the design process to utilize expert as well as heuristic knowledge of metallurgists to obtain designs which are realistic and which take account of the various limitations and constraints encountered in steelmaking. The material design is also characterized by extensive utilization of the grade history database which contains performance data for various steel grades and thickness combinations. The inputs to the system are through interactive dialogue sessions and the basic inputs consist of the material standards, size, quantity, tonnage, end use and customers' special requirements. These basic inputs along with the numerous rules in the knowledge bases as well as mathematical modelling enable the effective design of steelmaking aim chemistry.     

Tagged bremsstrahlung polarization: A Monte-Carlo approach

We present a Monte-Carlo approach for the determination of the degree of polarization of tagged bremsstrahlung. Our method allows the evaluation of the Bethe-Heitler expression in the photon-oriented reference system, while defining the photon and electron collimators in the spectrometer coordinate system. This avoids the need to perform fourfold integrals of complicated and bulky expressions. We reproduced the published calculations and measurements, and studied the polarization behavior as a function of several parameters in different geometric conditions.     

General analysis of concentration polarization in separation of multicomponent mixtures by baromembrane methods

A method for calculation of concentration polarization in separation of multicomponent mixtures by baromembranes with allowance for the mutual influence of the components in the process of molecular diffusion is described. Equations are derived for the concentration polarizations of binary and multicomponent mixtures under unsteady conditions. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 70, No. 1, pp. 55–59, January–February, 1997.     

胶束强化超滤技术分离水溶液中有色金属离子的研究

胶束强化超滤是一种实现水溶液中小分子量物质分离的新技术.该技术利用表面活性剂胶束对金属离子的吸附作用,结合超滤工艺,进而达到去除Cd2 ,Cu2 ,Ni ,Pb2 ,Co2 ,Zn2 等有色金属离子的目的.介绍了胶束强化超滤技术分离水溶液中有色金属离子的研究现状,分析了该技术目前存在的问题以及今后的应用前景.