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.     

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％。     

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。     

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.     

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。     

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。     

分相法制备微孔玻璃膜

微孔玻璃膜的制备是采用一定组成的Ｎａ２ＯＢ２Ｏ３ＳｉＯ２系玻璃，经５００～７００℃分相，再用酸液浸蚀其中的可溶相，即可得到具有一定孔径分布的微孔玻璃膜。讨论了化学组成和工艺条件对微孔玻璃膜孔结构的影响，探讨了这些因素对膜孔结构影响的基本规律，以便通过改变工艺条件来控制微孔玻璃膜的孔结构     

表面活性剂对泡载分离谷氨酸菌体的影响

本文考察了表面活性剂种类及浓度对泡载分离谷氨酸菌体的影响．结果表明，阳离子型表面活性剂对泡载分离菌体的影响趋势相同，不同离子型表面活性剂对分离菌体的作用机理不同；添加一定量絮凝剂可大大提高菌体分离效率；在发酵液中添加一定浓度表面活性剂和絮凝剂，可获得最佳分离效果．利用建立的动力学模型对实验数据进行了关联，结果较好     

膜法处理高浓度氨氮废水的研究

采用电渗析法和聚丙烯(PP)中空纤维膜法处理高浓度氨氮无机废水可取得良好的效果。电渗析法处理氨氮废水,浓度2000～3000mg／L,氨氮去除率可在85％以上,同时可获得8．9％的浓氨水。此法工艺流程简单、投资省、不消耗药剂、运行过程中消耗的电量与废水中氨氮浓度成正比。PP中空纤维膜法脱氨效率≥90％,回收的硫酸铵浓度在25％左右。此法工艺流程短、技术先进、省电,无二次污染,运行中需加碱,加碱量与废水中氨氮浓度成正比。     

Al2O3对硼硅酸盐玻璃热膨胀和分相的影响

通过红外光谱分析了Al2O3取代SiO2后硼硅酸盐玻璃结构的变化,测试了玻璃的热膨胀系数和膨胀软化温度,通过扫描电子显微镜分析硼硅酸盐玻璃的分相,并结合X射线能谱分析了富硅相的组成.结果表明:硼硅酸盐玻璃中引入Al2O3后,随着Al2O3取代量的增加,玻璃结构中[BO3]增多,[BO4]减少;玻璃的热膨胀系数增大,转变温度和软化温度提高;硼硅酸盐玻璃中引入Al2O3后对玻璃的分相没有明显的改善作用.