侧柏叶提取液超滤过程及修正凝胶极化模型

采用酶法提取、乙醇 水混合溶剂提取工艺提取侧柏叶有效成分，对提取液的超滤过程进行研究。建立了该体系超滤过程的修正凝胶化模型，对模型参数进行了关联。该模型可适用于整个超滤操作压力范围，计算值与实验值非常一致。     

超滤工艺水质模型研究进展

超滤在水处理行业得到日益广泛的应用,超滤工艺水质模型的研究对于理解过程机理和优化工艺运行具有重要意义。综述了超滤对溶质截留模型的研究进展,介绍了主要机理模型和经验模型的建模理论和方法、关键方程、主要参数等,并侧重从水处理行业适用性的角度评价了现有超滤工艺水质模型研究的不足,包括:以模拟单一溶质体系的模型为主、基于生产规模实际系统的模型极少、针对水处理行业的模型较少等。为了适应水处理行业中超滤工艺发展的需求,今后应加强超滤工艺过程机理的基础研究,探索将机理模型和经验模型相结合,开发更为有效实用的超滤工艺水质模型。     

平行板超滤系统过滤速率研究

在平行板流动超滤系统中,以0.15M NaCl、0.2%NaN_3的牛族血清白蛋白(BSA)溶液进行试验.讨论了操作压差、流速、浓度及蛋白质吸附等对过滤速率的影响;对平行板间滞流流动的超滤过程建立了过滤速率模型.采用两种方式确定膜面浓度:一般情况下将本文所得的过滤速率方程与Kozinski渗透压差模型联立,由试差法确定;在临界压差附近操作时,令膜面渗透压差等于操作压差,进行直接计算.实验表明,二者均具有满意的准确度.     

超滤(UF)技术处理乳化油废水的研究

采用超滤工艺一间歇式错流操作模型一处理乳化油废水,选用了聚乙烯乙二醇超滤膜(PEG)和卷式膜组件,采用不同的超滤模型对超滤过程中超滤膜透水率、乳化油废水中的COD去除率的变化进行了实验研究,实验结果表明该模型对乳化油废水具有良好的处理效果。     

操作条件对膜污染及蛋白质超滤滤出速度影响的研究

蛋白质溶液的超滤是超滤膜应用的重要领域之一蛋白质溶液的性质是影响超滤性能的重要因素,当蛋白质溶液性质一定时,操作条件成的影响超滤性能至关重要的因素,本文通过对不同材质超滤膜超滤蛋白质溶液地的操作条件与膜污染和滤出速度关系的研究,提出了蛋白质超滤时操作条件的优越方案。     

“患者”—伴有超滤的透析型人工肾系统三室模型的研究

利用五条大的肌酐联体实验数据,分析了生物体内不同组织之间溶质浓度分布系数及超滤对三室模型的影响程度,建立了一个同时考虑室间溶质浓度分布及超滤的三室模型修正式及一个可以转化为多种三室模型和二室模型的综合性三室模型式,并利用上述实验数据,对三室模型修正式进行了参数估值。     

超滤膜分离香菇多糖的研究

以本地劣质香菇为原料,利用超滤膜装置对浸提的香菇多糖进行分离。同时对超滤过程的阻力及传质特性进行分析,并建立超滤过程的修正凝胶极化模型。经过实验获得香菇多糖提取率5.7%,多糖质量分数89.2%,说明利用超滤方法分离浓缩香菇多糖是有效的工艺手段。     

超滤和纳滤膜分离提取纳他霉素

为提高纳他霉素(natamycin)生产提取得率,减少溶剂使用,本文采用超滤、纳滤操作对工业生产的纳他霉索发酵液进行处理。实验结果表明:操作压力、操作时间及料液流速对超滤过程有很大影响。通过超滤可将蛋白质等大分子杂质去除,然后再用纳滤膜对超滤渗透液进行浓缩纯化,对纳滤工艺的操作条件如进料压力、料液pH、浓缩倍数等进行了研究。采用超滤、纳滤技术提取纳他霉素,其收率可达62.74%。     

猕猴桃果水溶性多糖的超滤膜分离研究

以猕猴桃果为原料,利用超滤膜装置对浸提的猕猴桃果多糖进行分离。同时对超滤过程的阻力及传质特性进行分析,并建立超滤过程的修正凝胶极化模型。经过实验获得猕猴桃果多糖提取率5.7%,多糖质量分数89.2%,表明利用超滤方法分离浓缩猕猴桃果多糖是有效的工艺手段。     

聚合物乳液中N,N-二甲基乙酰胺分离方法研究

研究了聚合物乳液中N,N-二甲基乙酰胺(DMAc)溶剂的分离去除方法,对比分析了2种分离工艺(萃取和超滤)的可行性,并对影响超滤过程分离速率的温度和操作压力进行了进一步研究。研究发现:超滤工艺以其无相变、低能耗、不引入杂质、选择性好、工艺简单和高效等优势,成为该体系聚合物乳液中DMAc溶剂分离去除的最佳方法。采用的超滤工艺,不仅有效地从聚合物乳液中分离DMAc,而且分离出的DMAc水溶液为后续回收DMAc溶剂,降低了产品成本,减少了环境污染。     

平板超滤膜元件的微分方程模型

以平板超滤膜元件的理想结构及传递过程的平衡方程为基础,建立了超滤膜元件运行的微分方程数学模型。在分析元件运行参数基础上确认了微分方程的边界条件,使微分方程组具有唯一解。膜元件微分方程模型的建立为超滤膜元件结构及运行分析提供了理论参考,并为超滤系统运行模拟软件的编制建立了数学基础。     

Theoretical evaluation of ultrafiltration effect on the clearance of hollow fiber artificial kidney

The diafiltration of a hollow fiber artificial kidney is simulated with a one-dimensional model. The model equations are solved to give an explicit formula for calculating the clearance increase due to ultrafiltration. The computed results are compared with the experimental data of Kunitomo et al. (1977). The simultaneous diffusion and convection processes occur as if they occur consecutively when the overall permeability is small. The relationship between clearance and ultrafiltration rate is not linear as previous investigators reported because the outlet concentrations are dependent on the ultrafiltration rate.     

PROCESS OPTIMIZATION IN ULTRAFILTRATION: FLUX-TIME CONSIDERATIONS IN THE PURIFICATION OF MACROMOLECULES

An empirical model was developed to describe the flux of a complex milk protein suspension under ultrafiltration and diafiltration conditions. Flux decreased during ultrafiltration, but increased during diafiltration as the permeable solids concentration decreased. The “gel” model based on film theory was modified to describe the flux in terms of both retained and permeable solutes. The least-time processing strategy for a given end product concentration was also modelled and identified for this protein system. In general, ultrafiltration followed by diafiltration is best if protein purification is the goal.     

SOLUTE REJECTION IN THE ULTRAFILTRATION OF POLYDISPERSE ORGANICS FROM NATURAL PRODUCTS

Solute rejection in the ultrafiltration of solutions containing polydisperse solutes was modeled using a spherical solute/cylindrical capillary model, accounting for steric hindrance and wall drag effects. A power law relationship was used for the solute radius-molecular weight relationship. The three parameters in the nondimensional model are the ratio of mean pore radius/solute radius coefficient, the exponent in the solute radius versus molecular weight relationship, and the standard deviation of the logarithms of the pore diameters. Values of the parameters, obtained by fitting the model to rejection coefficient data for solutions containing dissolved organics from wood, were self-consistent and made physical sense. The model provides a useful tool for evaluating ultrafiltration membranes for specific solute fractionation applications.     

“患者”——伴有超滤的透析型人工肾系统双室模型的研究

本文建立了“患者”——伴有超滤人工肾系统的双室模型,该模型的解析解考虑了超滤对透析器溶质清除率和细胞外室体积变化的影响,具有较为普遍的意义.通过拟合犬-人工肾活体动物实验数据,对双室模型参数进行了辨识,获得了令人满意的结果.     

电场强化纤维素酶超滤过程研究

将电场强化膜技术应用于纤维素酶超滤过程,在截留相对分子质量为10 000的聚醚砜(PES)超滤膜上分别考察了电场对粗酶粉配制的纤维素酶模拟溶液以及秸秆酶解液的超滤过程的影响.实验结果表明,在2种情况下,电场均可以有效提高超滤过程的渗透通量.当电流强度为150 mA时,相对于无电场(0 mA)的条件下,纤维素酶模拟溶液通...     

Measurements and evaluation of concentration distributions in filter cake formed in dead-end ultrafiltration of protein solutions

To clarify the internal structures of the filter cake formed on the membrane surface in protein ultrafiltration, a method has been developed for measuring the variations of protein concentration across the filter cake on the basis of the principle of inclined ultrafiltration, where the membrane was inclined and a large amount of filter cake was formed, and the results were compared with the calculations based on a compressible cake filtration model, which explicitly took the non-homogeneity and the compressibility of the filter cake into account. The experimental results obtained from ultrafiltration of bovine serum albumin (BSA) solutions under constant pressure conditions clearly demonstrated that the filter cake tended to have a much more compact structure at the membrane in comparison with a relatively loose condition at the surface. It was also found that the thickness of the filter cake formed on the membrane increased as the filtration progressed. Further, the effects of pH and the solute concentration in the feed solution on the structure of the filter cake have been examined experimentally. The measured concentration distributions accorded well with the calculated results based on a compressible cake filtration model. This study revealed that the dynamic deposition behaviors of the protein molecules in dead-end ultrafiltration could be accurately described by a compressible cake filtration model.     

Studies on syntheses and permeabilities of special polymer membranes: 30. Ultrafiltration and dialysis characteristics of cellulose nitrate-poly(vinyl pyrrolidone) polymer blend membranes

The ultrafiltration and dialysis characteristics of the semipermeable polymer blend membranes obtained from cellulose nitrate, poly(vinyl pyrrolidone), and N,N-dimethyl formamide were investigated under various conditions. The water content fraction and the ultrafiltration rate were dependent on the poly(vinyl pyrrolidone) content in the membranes, and the strengths were governed by the cellulose nitrate content in the polymer blend. If the pore radius in the membranes, calculated according to the Hagen-Poiseuilli equation for capillary model, was identical, the water content in each membrane was not identical. It was found that urea molecules broke very weak hydrogen bonds of the bound water in the membrane, but sodium chloride did not, also, the diffusion of urea through the membrane was more rapid than that of sodium chloride. The ratio of the membrane diffusion coefficient to the ultrafiltration rate was explained qualitatively by the capillary model, however, when the bound water in the water content fraction was considered, this ratio showed better agreement with the model.     

Temporal evolution of resistances in the ultrafiltration of humic substances

Many ultrafiltration-related studies have emphasized fouling mechanisms, but few works have been done on resistance modeling. This study investigated the temporal variation of different resistances including membrane intrinsic resistance, fouling resistance, and concentration polarization resistance, based on a well established resistance--in-series model. The various resistances were determined at an early stage of ultrafiltration operation. During the initial operation period, the total filtration resistance for ultrafiltration of humic substance solution ranged from 1.9×10⁹ to 2.2×10⁹Pa·/m. The principal resistance of ultrafiltration is from intrinsic membrane resistance, accounting for more than half of the total resistance (56-85%).