ANALYSIS OF PREPARATIVE CHROMATOGRAPHY BY LOCAL EQUILIBRIUM MODEL

Closed-form equations for the first moment, the capacity factor, and the plate height (plate number) of a preparative chromatography in the case of a Langmuir isotherm were derived based on the local equilibrium model. These equations are applicable to the column under conditions of both concentration overload and volume overload. The effects of overload on the change of capacity factor and on the loss of column efficiency are accounted for explicitly by these equations. The predicted plate numbers under concentration overload are comparable with those resulting from equations in the literature and experimental data reported by previous investigators; whereas the predicted plate numbers under volume overload agree with the results from computer simulation. The equations obtained in this work provide a theoretical basis of the determination of thermodynamic parameters, the association constant and the maximum binding capacity, and serve as first approximations for the prediction of column capacity factor and band spreading in the case of mass transfer and adsorption-desorption at a finite rate whenever the column is operated under conditions of either volume overloading or concentration overloading.     

SEPARATION OF STABLE NITROGEN ISOTOPES BY ION EXCHANGE CHROMATOGRAPHY

ABSTRACT

The ion exchange chromatography technique was used for the enrichment of nitrogen 15 (¹⁵N). A set of columns filled with the ion exchange resin Wofatit KPS (medium porosity type) with 5.4?cm I.D. and 1.5?m height was set up. Ammonia NH₄ ⁺/NH₃ aq. was chosen as the isotopic exchange system. The ammonium bands formed in the columns were eluted by a solution of sodium hydroxide. The isotope separation factor, ?, was found to decrease with increasing temperature or ammonia concentration. Operational conditions of temperature and ammonium concentration were proposed as the optimum for the production of the enriched isotope by using the present process. Results showed that: (1) the rear part of the band is enriched in ¹⁵N, while the frontal part is depleted; (2) it is possible to obtain 7.6?at. % of ¹⁵N after a 60?m displacement of the ammonium band. The analytical determination of the samples was made by emission spectrometry (NOI-6E).     

MOVING PORT CHROMATOGRAPHY: A METHOD OF IMPROVING PREPARATIVE CHROMATOGRAPHY

A computer study of conventional, moving feed, moving withdrawal and moving port chromatography systems was conducted. The linear ternary system of naphthalene, anthracene, and pyrene in 2-propanol with Polyclar AT as the stationary phase was studied. Moving withdrawal ports in conjunction with moving feed chromatography (moving port system) resulted in an average increased purity of 22% and an average increased throughput of 120% compared to conventional chromatography. Moving feed chromatography increased purity by 22% and throughput by 33%, and moving withdrawal chromatography increased throughput by 39% over the conventional case with no change in purity. A local equilibrium model with zone spreading was also developed and use to determine reasonable operating conditions for these chromatographic systems.     

MOVING PORT CHROMATOGRAPHY: A METHOD OF IMPROVING PREPARATIVE CHROMATOGRAPHY

A computer study of conventional, moving feed, moving withdrawal and moving port chromatography systems was conducted. The linear ternary system of naphthalene, anthracene, and pyrene in 2-propanol with Polyclar AT as the stationary phase was studied. Moving withdrawal ports in conjunction with moving feed chromatography (moving port system) resulted in an average increased purity of 22% and an average increased throughput of 120% compared to conventional chromatography. Moving feed chromatography increased purity by 22% and throughput by 33%, and moving withdrawal chromatography increased throughput by 39% over the conventional case with no change in purity. A local equilibrium model with zone spreading was also developed and use to determine reasonable operating conditions for these chromatographic systems.     

超临界流体色谱法制备EPA-EE和DHA-EE

以二氧化碳作流动相,C18柱为固定相,用超临界流体色谱法制备二十碳五烯酸乙酯(EPA-EE)和二十二碳六烯酸乙酯(DHA-EE).考察了流速、温度、压力、上载量以及进样浓度对制备分离的影响.结果表明,在实验范围内,流速对分离效果影响不大.对于5-C18,250mm×4.6mm色谱柱,其最适制备条件是柱前压12MPa,温度55℃,通常流速下的压降约为1MPa,鱼油的最大上载量大于20μl.而对于8-C18,250mm×10mm色谱柱,其相应的最适制备条件是柱前压11MPa,温度55℃,通常流速下的压降约为0.5MPa,鱼油的最大上载量约为100μl.实验表明,鱼油无需溶解于其他溶剂而可直接进样.     

高效液相色谱分离定量硝基芳香族化合物

本文采用反相高铲液相色谱法，择用国产液相色谱填料ＹＷＧ－Ｃ１８Ｈ３７自行装柱，甲醇、水为流动相、分离定量硝基芳香族化合物，获得优佳色谱条件及满意的定量结果。     

用粉碎及分离工艺制备SiC片晶

采用不同的粉磨设备，在不同的实验条件下粉磨工业ＳｉＣ原块至一定粒度，发现粉磨产品的形貌及馘 晶的含量与磨机的种类，作用方式及操作条件有关。得用不同粒径与形状的颗粒在介质中自由沉速度的差异，把ＳｉＣ粉末分成若干粒级，然后通过自行设计，制造的分离槽，对同一粒级的颗粒进行按形状分离，从而获得片晶含量极高的产品。     

连续泡沫分离蛋白质

本文以空气-明胶水溶液体系为研究对象，较为详细地考察了通气量、进料流量、进料浓度、进料位置、泡沫高度、溶液pH值等因素对连续泡沫分离明胶过程中明胶富集度变化的影响．     

35m2跳汰机分选效果的分析及改进措施

通过对现场ＸＴ５４３２跳汰机分选效果及存在的问题的分析,对要更换的新跳汰机提出了改进措施。     

TREATMENT OF KRAFT PULP AND PAPER WASTEWATERS BY MEANS OF FOAM SEPARATION

The pulp and paper industry is the third largest industrial consumer of fresh water in the United States. The current use rate of over two trillion gallons annually is expected to increase as the demand for paper products continues to rise

Of the various methods of producing paper from wood, the Kraft process is the most widely used. Color, dissolved and suspended organic matter, and dissolved inorganic solids are major pollutants in Kraft processing wastewater. Current federal regulations limit the amount of solids and organic matter that a Kraft facility may dispose into public waters, so most plants have some form of wastewater treatment

In this study, the capacity of a continuous-flow, foam separation system to effect removals of color from a Kraft process wastewater was evaluated. The cationic surfactant, EHDABr, was used to precipitate color bodies in the wastewater and create a foam to carry the precipitates from the wastewater. The effect of pH adjustment was also considered. Color removals in the area of 90% were achieved

Removal of precipitated solids was enhanced by increasing the detention of wastewater in the treatment system.     

SEPARATION OF METALS BY CONTINUOUS ANNULAR CHROMATOGRAPHY WITH STEP ELUTION

A continuous annular chromatograph (CAC) was used to separate dilute aqueous mixtures of iron and chromium salts using Dowex 50W-X8 as the sorbent. While an isocratic separation of the two species could be easily obtained, this mode of operation resulted in excessive dilution of the products. Introduction of a step in eluent concentration, however, permitted a much more efficient separation of the two metals. Separation of Fe³⁺ and Cr³⁺remained nearly complete but elution of the more strongly retained species (Cr³+) occurred over a much narrower angle and dilution of the product streams was significantly reduced or even eliminated in some cases. A theoretical model was developed to describe the operation of the continuous annular chromatograph with step elution. With the inclusion of significant dispersive factors (axial dispersion and film mass transfer resistance), the solution of the model equations provided an excellent prediction of the experimental CAC data. Similar improvements to the CAC performance can also be obtained for other separations by manipulating the appropriate variables in a similar manner.     

磁种混凝-高梯度磁分离技术的印染废水处理

应用自制的高梯度磁分离装置处理印染废水,结果表明,低剂量Fenton氧化-磁种混凝-高梯度磁分离技术处理色度为800倍、COD为565．0mg／L的成分复杂印染废水效果良好,色度、COD的去除率分别达到92．6％和79．5％,符合国家二级排放标准。最佳工艺条件为：pH=6,FeSO4-7H2O=250mg／L,H2O2=1．3mL／L,PAM=0．75mg／L,磁粉加入量150mg／L,电流强度8A,水样流速2．420L／min,不锈钢丝绒填充率1．00％～1．43％。     

MATHEMATICAL AND EXPERIMENTAL ANALYSIS OF AIR SEPARATION BY HOLLOW FIBER MEMBRANES

Approximate solutions for gas separation by hollow fiber membranes have been developedby several investigators.However,there are few reports of experimental verification of the models forhigh stage cut separations.In this work,an approximate mathematical model was developed and wasexperimentally verified for high stage cut air separation.Both countercurrent and cocurrent now pat-terns were used.In addition,the applicability of feed-inside mode for low stage cut air separation byhollow fiber membrane was examined.It was found that feed-inside mods was more advantageousthan feed-outside mode when used for the generation of oxygen-enriched air.     

聚醚砜增韧环氧树脂的力学性能及固化体系相分离

环氧树脂是高性能纤维增强复合材料中应用最广泛的热固性基体树脂之一,但是环氧树脂固化后交联密度高、内应力大、质脆、耐疲劳性与耐冲击性差等不足在很大程度上限制了它在一些高技术领域的应用。利用聚醚砜(PES)对环氧树脂(E51)进行增韧改性,利用热熔法制备不同PES含量的PES/E51体系,加入E100固化剂制备成浇注体。利用热台偏光显微镜观察PES在E51中的溶解情况,采用拉伸、冲击等力学性能评价不同PES含量PES/E51/DETD浇注体的力学性能,利用热台偏光显微镜研究体系的相分离过程,采用扫描电子显微镜(SEM)观察固化后树脂体系的相分离情况。结果表明,PES与E51树脂具有良好的相容性,PES的加入可有效改善固化树脂的力学性能,相对于未固化环氧树脂,加入15wt%PES的浇注体拉伸强度和冲击强度分别提高了1.3倍和2倍,并且浇注体固化过程中出现相分离现象,15wt%PES的浇注体出现双连续相结构,使得力学性能表现出最优化。     

气相色谱法测定聚合物乳液中残余单体

将聚合物乳液样品进行简单的稀释,采用程序升温气相色谱方法,一次进样,只用20分钟即可分离定量MA,MMA、EA、BA、iBA、2-EHA、HPA、AN、VAC及St等。最低检测量达50ppm,个别达5ppm。实践证明,该方法可行,结果可靠。     

EXTRACTIVE SEPARATION OF URANIUM AND ZIRCONIUM SULFATES BY AMINES

ABSTRACT

This paper describes an amine extraction process for zirconium and uranium separation. The behaviour of an extraction system containing uranium (VI) sulfate, zirconium (IV) sulfate, 0.2 and 0.5 M sulfuric acid (as the original aqueous phase), tertiary amine tri-n-lauryl- amine or primary amine Primene JMT in benzene (as the original organic phase) is discussed on the basis of equilibrium data.

The measured dependences show that the degree of extraction of zirconium at the sulfuric acid concentration of 0.5 M and above is only slightly affected by a presence of uranium in solution. From this surprising behaviour it follows that zirconium may be employed for the displacement of uranium from the organic phase. This effect is more pronounced with the primary amine Primene JMT than with TLA.     

多效膜蒸馏技术分离尿素水溶液的研究

应用新型多效膜蒸馏技术,对尿素水溶液体系进行分离试验研究。用正交试验方法对操作条件进行优化设计,结果表明,在试验范围内,当膜侧进口温度90℃,料液流量30 L/h,料液初始质量分数0.5%,膜通量最大;当膜侧进口温度90℃,料液流量10 L/h,料液初始质量分数0.5%,造水比最大;膜通量随膜侧进口温度升高而增加,膜通量随进料流量增大而增加,造水比反之。     

热扩散塔分离甲烷和氢的实验研究

引言用甲烷直接合成C_2以上的碳氢化合物非常困难,例如,由甲烷脱氢合成乙烯,按热力学计算在1000K下甲烷的平衡转化率只有4.8％,所以至今甲烷仍主要用作燃料．为了充分利用这一化工基础原料,作者利用热扩散塔进行了甲烷的催化脱氢反应,使反应与分离同时进行,大幅度提高了甲烷的转化率．为考察热扩散的分离效果,本文用甲烷脱氢反应的主要成分甲烷和氢混合物为原料,在热扩散塔中分别进行了空塔和填料塔的热扩散分离实验,考察了一些操作参数对分离效果的影响,以期对反应操作条件提供必要的参考．l原理所谓热扩散现象,就是在温度场…     

液膜法迁移及分离镍(Ⅱ)的研究

本文采用内耦合大块液膜分离技术，考察了搅拌速度、料液相pH值、体系温度、载体浓度对镍(Ⅱ)迁移率的影响，研究了以烷基膦酸为载体的液膜中镍(Ⅱ)的迁移规律。结果表明，镍(Ⅱ)的迁移率随温度和载体浓度的升高而逐渐增大，当迁移条件为搅拌速度300～350r／min、料液相pH值5．3～5．8、载体浓度5．5％～7．5％、温度293～310K时，镍(Ⅱ)即可快速并完全迁移。