Membrane system design for multicomponent gas mixtures via mixed-integer nonlinear programming

An optimal design strategy for membrane networks separating multicomponent gas mixtures based on an approximate permeator model and mixed-integer nonlinear programming (MINLP) is proposed. A permeator system superstructure is used to embed a very large number of possible network configurations and allows the permeator feed-side pressure to be fixed or a design variable. A MINLP design model is developed to minimize the total annual process cost by simultaneous optimization of the permeator configuration and operating conditions. Case studies for the separation of acid gases (CO₂ and H₂S) from crude natural gas mixtures with spiral-wound permeators are presented. Permeator configurations are derived for different number of separation stages for both continuous and discrete membrane areas. The method is sufficiently robust to handle product compositions that vary five orders of magnitude. The proposed approach provides an efficient methodology for preliminary screening of multi-stage membrane separation systems for multicomponent gas mixtures.     

Magnetic Extraction,Detection, and Isotope Analysis of Metal Ions Using Surface Modified Microspheres for Lab-on-a-Chip Applications

Liquid–liquid extraction and ion-exchange chromatography are efficient methods for sequestration of metal ions, but these methods are poorly suitable for microfluidic miniaturization. Here we examine several methods for rapid extraction, fluorometric detection, and the subsequent isotope analysis of lanthanide ions sequestered on surface modified magnetic microspheres as a versatile platform for chemical manipulation. The assays involve immobilization of a mixed-ligand complex of luminescent lanthanide ions at the surface of polystyrene microspheres. Using the ion-exchange properties of these microspheres, this scheme can be extended to the detection of nonluminescent ions.     

Characterization of Extraction of Chromatographic Materials Containing Bis(2‐ethyl‐1‐hexyl)Phosphoric Acid, 2‐Ethyl‐1‐Hexyl (2‐Ethyl‐1‐Hexyl) Phosphonic Acid,and Bis(2,4,4‐Trimethyl‐1‐Pentyl)Phosphinic Acid

Abstract

This work describes the uptake of a wide range of metal ions, including alkaline earths, transition metals, post‐transition metals, lanthanides and actinides, from acidic nitrate and chloride media on extraction chromatographic resins prepared from three different acidic organophosphorus compounds: bis(2‐ethyl‐1‐hexyl) phosphoric acid (HDEHP), 2‐ethyl‐1‐hexyl(2‐ethyl‐1‐hexyl)phosphonic acid, (HEH[EHP]) and bis(2,4,4‐trimethyl‐1‐pentyl)phosphinic acid (H[DTMPP]). The data is plotted in a format allowing for the easy comparison of the uptake of all metal ions under a given condition. Additionally, examples of several novel separations using the three extraction chromatographic materials are discussed.     

Bipolar membrane electrodialysis for clean production of L-10-camphorsulfonic acid: From laboratory to industrialization

In this study, bipolar membrane electrodialysis (BMED) was implemented for cleaner production of L-10-camphorsulfonic acid (L-CSA) to lower the environmental impact. Under the current density of 300–400 A/m² and feed salt concentration of 6–10 wt.%, the energy consumption and current efficiency were 2.24–2.70 kWh/kg and 20.89–29.5%, respectively. Positron annihilation lifetime spectroscopy, x-ray photoelectron spectroscopy with ion beam etching, and other characterizations were used to elucidate the transport behaviors of large-sized anions across the membranes. It was speculated that the large-sized camphor sulfonate ions were more likely to deposit on the surface of the anion-exchange membrane to form a deposition layer under a direct current electric field. The appearance of water splitting at this deposition layer would offset the water dissociation in the bipolar membrane. Nevertheless, the successful commissioning of industrial-scale stack proved the feasibility and sustainability of BMED technique for a closed loop L-CSA production.     

Model for a cascade continuous epoxidation process

A steady-state mathematical model was developed to analyze the performance of a cascade continuous epoxidation process that was applied to the epoxidation of unsaturated compounds with in-situ-formed performic acid. The model equations were nonlinear, and the model prediction was calculated by solving the model equations using a numerical solution procedure. The experimental results supported the model prediction in that good agreement between the model predictions and experimental results was achieved. The model is necessary for precise operation control, process estimation, and operating parameter optimization and regulation, and will provide a theoretical foundation and research method for automatic control and engineering scale-up.     

丁醇－丙酮－乙醇－水多组分精馏过程分析计算

针对某厂生产长期不正常的实际情况，用ＡＳＯＧ式对丁醇－丙酮－乙醇－水四组分溶液进行了相平衡计算，并对多塔系统作了逐板模拟分析核算，找出了该厂设计中的不足，使产品质量迅速达标     

Magnetic separations in biotechnology—a review

Magnetic separation technology has a broad range of potential applications in both small and large scale biotechnology. This review considers a selection of magnetic techniques and their possible uses.     

丁醇－丙酮－乙醇－水多组分精馏过程分析计算

针对某厂生产长期不正常的实际情况，用ＡＳＯＧ式对丁醇－丙酮－乙醇－水四组分溶液进行了相平衡计算，并对多塔系统作了逐板模拟分析核算，找出了该厂设计中的不足，使产品质量迅速达标     

Chromatographic separation of polylactides by stereochemical composition

Polylactides exist in different stereochemical compositions, as pure l-(PLLA), pure d-(PDLA), or mixtures containing the two enantiomeric forms in varying amounts. Polylactides of different stereochemical compositions differ in their solubility in THF. Based on the difference in solubility a gradient chromatographic method was developed allowing separation of polylactides differing in their stereochemical compositions (excess of enantiomers, e.e.). Moreover, blends composed of polylactides having different stereochemical purity could be separated into their individual components. However, for mixtures of PDLA with PLLA an additional peak was observed at higher elution volume. Since this peak cannot be attributed to any of the individual components, this peak might result from the formation of the stereocomplex described in literature.     

基于组件技术的虚拟测试系统开发

将传统的通用信号发生器与通用的测试仪的功能通过LabVIEW这个软件开发平台实现功能的高度集成,开发一种通用自动测试系统。以计算机和数据采集卡为基本硬件来实现激励信号的产生和响应信号的采集,本系统采用软件工程中面向组件的设计思想,从而使繁琐的编程过程转变为组件的开发和搭接两个步骤,同时采用严格数据类型的枚举控件,极大地提高了系统的可重用性和可扩展性。同时利用LabVIEW中同步控制技术中的Queue技术来完成通用自动测试系统组件的搭接,从而实现了信号源和测试仪的集成,由此避免了数据的丢失。     

超声波技术及应用(Ⅲ)--超声波在分离技术方面的应用

对超声在提取、膜分离、结晶、絮凝、吸附与脱附、泡沫浮选及双水相萃取等分离技术中的应用进行了综述;超声波具有许多独特效应,如空化效应、湍动效应、微扰效应、界面效应和聚能效应等,因此能够提高传质系数,强化分离过程,结合各自分离过程的特点,分析了超声强化各分离过程的作用机制;指出目前超声在分离技术方面的研究重点。     

Synergistic Enhancement of the Extraction of Trivalent Lanthanides and Actinides by Tetra‐(n‐Octyl)Diglycolamide from Chloride Media

Abstract

This work describes a unique synergistic enhancement of the extraction of trivalent actinides and lanthanides by extraction chromatographic resins containing tetra‐n‐octyldiglycolamide (TODGA) from hydrochloric acid containing anionic metal chlorides. The presence of mg/L quantities of trivalent Fe, Ga, In, Tl, or Bi in HCl leads to several orders of magnitude enhancement of the extraction of trivalent actinides and lanthanides. The synergistic effect persists, even when the amount of metal chloride exceeds the capacity of the resin. The application of this synergistic enhancement for the separation of actinium from stainless steel and the preconcentration of americium and plutonium from large soil samples will be described.     

Which separation scenarios are advantageous for membranes or distillations?

We systematically analyze power requirements of membrane and distillation processes for binary mixtures where the desired product component is more permeable and also more volatile. We first derive a shortcut method to compare the efficiency of heat pump and steam-driven distillations. Then, power requirements of heat pump distillation and membrane separation are discussed. Distillation generally requires lower power when either high component recoveries are needed (at all tested product purities), or high purity product streams with modest recoveries are needed. For high purity products at modest recoveries, membranes have a potential to provide energy benefits for highly enriched feeds, especially those composed of close boiling components. Additionally, when feed concentration is moderate to high and product recovery and purity are modest, membranes are likely to show efficiency gain. For the advantageous distillation scenarios studied, the power was generally lower than the membranes by a factor of two to seven.