反相层析分离紫杉醇的柱动力学

通过考察物质在液固两相之间的基本传递现象 ,建立了常压非线性柱层析过程的速率模型 .对紫杉醇在C18-硅胶柱上分离纯化过程进行了数学分析 .模型计算值与实验值吻合良好 .研究物料浓度、进料速度、层析柱大小等因素对紫杉醇层析过程的影响说明 ,建立的柱动力学模型能指导紫杉醇层析过程简捷而有效地放大     

紫杉醇在常压反相层析柱上的纯化

在C18^－胶柱上常压反相层析法对从云南红豆浸膏中初分离的紫杉醇进行了纯化精制。对C18^－硅胶层析纯化紫杉醇的操作条件进行了优化,并对层析进料量及紫杉醇回收率的有效提高进行了研究。采用本工艺分离精制紫杉醇精品,可使紫杉醇含量从25％左右提高到98％以上,回收率大于85％。     

活性炭-疏水硅胶复合吸附剂吸附油气

开发出一种上层为活性炭、底层为疏水硅胶的复合吸附剂,并与活性炭、硅胶单独吸附汽油蒸气进行比较,发现不同吸附剂及油气质量浓度对吸附容量及吸附热有大的影响。研究活性炭与硅胶不同体积比对吸附质量比和温度的影响,得出最佳体积比为1∶1。这样高质量浓度油气先被底层的硅胶吸附,低质量浓度的油气再被上层的活性炭吸附,从而综合利用了硅胶的不燃烧及活性炭吸附质量比高的特点,从工艺技术上降低了活性炭吸附放热的安全问题,进而还可适当提高活性炭有效吸附容量。     

大孔树脂纯化萼翅藤总黄酮工艺

筛选纯化萼翅藤总黄酮的最佳树脂,并对影响这种树脂分离的主要因素进行研究,确定大孔树脂纯化总黄酮的最佳工艺参数。选择4种大孔树脂分别对萼翅藤总黄酮进行静态与动态吸附性能研究,考察影响分离的各种因素如上样液pH值、上样液质量浓度、上样量和洗脱剂体积分数等。HPD-450树脂分离效果最好,Langmuir等温吸附模型较Freundlich模型更适宜描述树脂对萼翅藤总黄酮的吸附,其吸附分离萼翅藤总黄酮的最佳工艺为:上样液pH值为5,质量浓度为0.6—0.8 mg/mL,上样量为3 BV(树脂床体积),洗脱液为体积分数70%的乙醇,洗脱剂用量为3 BV。经HPD-450树脂吸附分离后,总固物中总黄酮质量分数从20.23%提高到75.86%,纯度提高了3倍多,回收率为62.65%。     

硅胶材料对典型油气组分正戊烷分子的吸附行为及吸附动力学

选用3种不同结构的商用硅胶(A型、B型和C型),利用物理吸附仪详细表征了孔结构参数;在298.15 K下测定了不同浓度典型油气组分正戊烷分子在硅胶上的动态吸附穿透曲线,计算了对应的平衡吸附量,并研究了硅胶对正戊烷分子的吸附行为。结果表明,A型硅胶在微孔有大量分布,B型和C型硅胶则为典型的介孔材料;通过对比分析硅胶孔结构对平衡吸附量的影响,确定了具有1⁴ nm孔径分布的A型硅胶为适宜的正戊烷分子吸附材料。同时,相比于准二阶动力学方程,正戊烷分子在硅胶上的吸附行为更符合准一阶动力学方程。     

硅胶材料对典型油气组分正戊烷分子的吸附行为及吸附动力学

选用3种不同结构的商用硅胶(A型、B型和C型),利用物理吸附仪详细表征了孔结构参数;在298.15 K下测定了不同浓度典型油气组分正戊烷分子在硅胶上的动态吸附穿透曲线,计算了对应的平衡吸附量,并研究了硅胶对正戊烷分子的吸附行为。结果表明,A型硅胶在微孔有大量分布,B型和C型硅胶则为典型的介孔材料;通过对比分析硅胶孔结构对平衡吸附量的影响,确定了具有1~4 nm孔径分布的A型硅胶为适宜的正戊烷分子吸附材料。同时,相比于准二阶动力学方程,正戊烷分子在硅胶上的吸附行为更符合准一阶动力学方程。     

超临界流体色谱法制备高纯度EPA-EE和DHA-EE

以二氧化碳作流动相,分别以极性相反的C18柱和硅胶柱为固定相,用超临界流体色谱法分离二十碳五烯酸乙酯(EPA-EE)和二十二碳六烯酸乙酯(DHA-EE)。比较C18柱和硅胶柱分离EPA-EE和DHA-EE的机理和分离效果,提出结合C18柱和硅胶柱的超临界流体色谱制备高纯度EPA-EE和DHA-EE的方法。     

C2H4/CO2混合体系在活性炭上吸附的实验与模型

通过重量法测定吸附等温线,研究了C2H4/CO2混合体系在活性炭上的吸附分离。采用高精度的智能重量分析仪,测定了C2H4和CO2纯组分以及混合组分在活性炭上的吸附等温线,将测量值与DL-IAST模型计算值进行比较,并计算出了C2H4的吸附选择性。结果表明,DL-IAST模型可以准确地描述C2H4和CO2纯组分在活性炭上的吸附;不同摩尔分数下,C2H4/CO2混合体系的DL-IAST模型计算值与实验值吻合得较好,C2H4摩尔分数越大,模型的相对偏差就越小;随着压力的增加,C2H4的吸附选择性减小,C2H4摩尔分数越大,C2H4的吸附选择性也减小。DL-IAST可以准确地描述C2H4/CO2混合体系的吸附等温线以及推算出C2H4的吸附选择性。     

银离子配位柱层析法分离姜油树脂中的姜烯

以测定姜烯银离子配合物稳定常数为基础,对比姜烯在硝酸银硅胶及硅胶表面的静态吸附情况以及姜油树脂在上述两种层析介质中的薄层分离情况,采用硝酸银硅胶柱层析法分离了姜油树脂中的姜烯。结果表明,当硅胶作为层析介质时,姜烯静态吸附量较小,当硅胶经硝酸银改性后,增强了姜烯的静态吸附能力,吸附行为近似典型的Langmuir吸附。姜烯能与硝酸银形成π配位化合物,其稳定常数为1.46×10-2 L/mol;倍半萜π配位化合物的稳定性与不饱和化合物的结构及溶剂环境有关,因此,硅胶经硝酸银改性后对不饱和化合物具有选择性吸附的能力,使姜烯可以与其他烯类物质分离,所得样品中姜烯质量分数为97.22%,收率为87.15%。     

壳聚糖-硅胶复合物对刚果红的吸附性能研究

研究了壳聚糖-硅胶复合物对水溶液中染料刚果红的吸附性能,探讨了吸附剂用量、p H值、吸附时间、温度对吸附性能的影响。实验发现,在p H 5～9之间,对于300 mg/m L的刚果红染料(30 m L),当壳聚糖-硅胶复合物为30 mg时吸附能力最强,去除率超过98%。从动力学分析可知,壳聚糖-硅胶复合物对刚果红的吸附过程符合准二级动力学模型;吸附热力学研究表明,壳聚糖-硅胶复合物对刚果红的吸附符合Langmuir模型,该吸附过程是一个吸热、熵增的自发过程。     

Impregnation and Characterization of High Performance Extraction Columns for Separation of Metal Ions

Impregnation behaviors of reverse-phase silica materials and C18-silica HPLC columns were studied using di-(2-ethylhexyl)phosphoric acid (HDEHP) as a model extractant. Initially, the adsorption efficiency of the ligand on different types of bulk particles was investigated using various concentration of HDEHP in different composition of methanol/water mixtures based on a batch technique. Subsequently, impregnation of HPLC columns was performed using the dynamic flow-through technique. The experimental data fitted well to the Langmuir model and the adsorption isotherms from the flow-through experiment were used to prepare extraction columns of different ligand densities. Finally, the impregnated columns were characterized and validated through HPLC separation of the lanthanides.     

C18-硅胶的原位合成及其作为常压层析介质在紫杉醇分离纯化中的应用

以氯铂酸为催化剂,采用原位法合成了造价低廉、性能稳定的Ｃ１８－反相层析介质。考察了原位法第二步反应中催化剂、反应时间及反应温度等对介质合成的影响。将合成的Ｃ１８－硅胶应用于紫杉醇的常压层析提纯,可使紫杉醇的纯度从２７％提高到９５％以上,回收率大于９０％。     

Biofilter modeling for waste air treatment: Comparisons of inherent characteristics of biofilter models

The types of biofilter modeling may be primarily classified in accordance with whether a biofilm is differentiated from other phases in each model. It may be a secondary classification with regard to biofilter-modeling whether sorption volume and/or adsorption are adopted as reservoirs or not. Thirdly, biofilter models are classified as to whether adsorption is assumed to exist through gas phase and/or a biofilm. Among all the biofilter-models of previous investigators all model-components including gas phase, a biofilm, sorption volume and adsorption surface are considered only in the model of Lim. Since his model does not require a numerical solution but an algebraic solution to describe the concentration of organic pollutants in waste-air-streams along the height of a biofilter even under unsteady-state conditions, it satisfies the condition of simplicity that is one of the important model requirements. In spite of its simplicity, Lim's model predictions are fairly good to fit Hodge and Devinny’s experimental data.     

聚丙烯酸/锂藻土纳米复合水凝胶对亚甲基蓝吸附性能的研究

研究了聚丙烯酸/锂藻土纳米复合水凝胶对染料亚甲基蓝的吸附性能,考察了不同吸附条件,包括凝胶用量、染料浓度、吸附时间及溶液p H条件等对水凝胶吸附效果的影响。实验结果表明,水凝胶对亚甲基蓝的吸附过程在30 min内即能达到平衡,吸附速度快;最大吸附容量高达1 192.9 mg/g,是普通吸附剂吸附容量的几十倍,吸附效果好;凝胶的吸附等温线拟合结果符合Freundlich模型,动力学拟合结果显示,凝胶对亚甲基蓝的吸附过程符合二级动力学模型。     

H6P2W18O62/MIL-101(Fe)材料的制备及其吸附性能

采用溶剂热合成法在制备MIL-101(Fe)的过程中引入杂多酸H_6P_2W_(18)O_(62),制备出吸附剂H_6P_2W_(18)O_(62)/MIL-101(Fe),并测试了其对亚甲基蓝(MB)的吸附性能。考察了H_6P_2W_(18)O_(62)的负载量、MB质量浓度、溶液pH、温度等对材料的吸附性能。通过XRD、SEM、FTIR、N2吸附-脱附等手段对材料进行表征。结果表明:吸附平衡前,吸附量随MB质量浓度的增加而增加,在溶液pH=4、H_6P_2W_(18)O_(62)负载量相对于复合物质量分数为35%的条件下,吸附剂H_6P_2W_(18)O_(62)/MIL-101(Fe)对亚甲基蓝溶液吸附效果最佳,在303K下H_6P_2W_(18)O_(62)/MIL-101(Fe)对MB的最大吸附量可达148.1 mg/g。通过动力学和热力学分析,该吸附过程符合拟二级动力学与Langmuir等温吸附模型,同时是一个吸热、自发的过程。     

Kinetic studies in a batch reactor using ion exchange resin catalysts for oxygenates production: Role of mass transfer mechanisms

Oxygenated compounds are usually produced by a reversible liquid phase reaction using ion exchange resins with a bidisperse pore structure as catalyst. Mass transport is mainly controlled by diffusion through the macropores and the mass transfer resistance in the gel microspheres is negligible. Therefore, in this paper a mathematical model of the batch reactor considering diffusion of the species in the external film and then macropore diffusion inside the particle and reaction in the gel microspheres was developed. The numerical solution is implemented through the numerical package PDECOL and detailed explanations of the procedure used are presented. The model was applied to the diethylacetal synthesis using ethanol and acetaldehyde as reactants and Amberlyst 18 as catalyst. The experimental data are fitted with a two-parameter model based on a Langmuir-Hinshelwood rate expression in order to get the true reaction kinetics. The influence of the mass transfer mechanisms is evaluated in terms of the effectiveness factor history during the transient state of the batch reactor. The values of the effectiveness factor calculated at equilibrium with the batch reactor model are compared with those calculated from a steady state infinite bath model.     

Double-stimuli responsive O/W emulsion gel based on a novel amidoamine surfactant

A heat-induced O/W emulsion gel that undergoes a phase transition from sol to gel on heating was formed from the addition of aqueous HCl to a toluene solution of a long-chain amidoamine derivative (C18AA). The heat induced O/W emulsions are highly sensitive to temperature, and the sol-gel transition temperature could be simply controlled by adjusting the C18AA concentration. Interestingly, the sol-gel transition of the O/W emulsions was also very sensitive to pH. Thus, we have successfully prepared a novel double-stimuli responsive gel based on O/W emulsions consisting of C18AA and HCl.     

Transport of direct dye into cellulose membrane

The dyeing process for a cellulose membrane–direct dye system is analyzed based on a parallel transport mechanism of surface and pore diffusion with Freundlich isotherm. Numerical solutions were obtained in order to clarify how the surface and pore diffusion resistances affect the uptake curve. The numerical solutions were also compared with an analytical solution for surface diffusion control to establish the range where the analytical solution can be considered as an acceptable approximation. The uptake curves in the cellulose membrane-chromophore (C.I. Direct Yellow 12) system in the presence of inorganic electrolyte were measured. The rate of adsorption and the maximum amount of adsorption increased with an increase in the concentration of those electrolytes. The rate of adsorption was approximately controlled by the surface diffusion rather than by pore diffusion. The surface diffusivities of the dye were little affected by either the concentration and or nature of the electrolyte.