Uphill permeation model of gold(III) and its separation from base metals using thiourea derivatives as ionophores across a liquid membrane

This work deals with carrier-facilitated membrane transport of Au(III) from chloride media across a polymer-immobilised liquid membrane (PILM) using as organic reagents N-(thiocarbamoyl)benzamide derivatives and N-benzoylthiourea derivatives, denoted as 2a–c and 3a–f, respectively. Both the composition of the organic membrane solvent and the type of carrier have a marked effect on gold permeation. Recovery and permeability of gold using 2a–c and 3a–f across a PILM proceed in the following order: 3e≈3d≈3c?3f>3b≈3a≈2a≈2b≈2c. In view of the performance of these carriers, 3c was selected as a metal receptor for detailed studies of Au(III) in permeation. A model is presented for the permeation of Au(III) (61 μM) in 0.5 M Cl⁻ at pH 2.5 using 3c as a membrane carrier. The mathematical equations describing the rate of permeation are derived to correlate the membrane permeability coefficient with diffusional and equilibrium parameters. The mass transfer coefficient was calculated from the described model as 1.1×10⁻⁵ m s⁻¹, and the thickness of the aqueous boundary was later calculated to be 65 μm. Several polymeric supports were tested for impregnation of the organic extractant, and Durapore (Millipore) afforded the maximum flux for Au(III), yielding a value of 1.1×10⁻¹⁴ mol m⁻² s. The relationship between flux and support characteristics is derived and a mathematical equation is presented. Of the several diluents used, cumene had the most satisfactory performance in terms of PILM stability and metal transport. Of the different reagents used, 0.5 M sodium thiocyanate in 0.5 M NaCl at pH 2.5 served most efficiently as the stripping agent. More than 80% of the Au(III) could be readily separated using 3c in the presence of various metals such as Cu(II), Fe(III) and Zn(II).     

Multicomponent complexes of piroxicam with cyclodextrins and hydroxypropyl methylcellulose

The purpose of the study was to investigate the effect of hydroxypropyl methylcellulose (HPMC) on the complexation of piroxicam (PX) with β-cyclodextrin (β-CD) and dimethyl-β-cyclodextrin (DM-β-CD) in solution and in the solid state. Phase solubility study revealed a positive effect of the polymer on the drug complexation. Improvement in stability constants values, K_s, of ternary complexes clearly proves the benefit of the HPMC addition for promoting higher complexation efficiency. Solid binary and ternary complexes were prepared by spray drying. Drug-CD and drug-CD-polymer interactions were studied in the solid state by differential scanning calorimetry (DSC), zeta-potential measurements, and particle size distribution. A marked increase in the PX dissolution rate was observed even in binary and ternary complexes. The presence of HPMC in ternary complexes slightly retarded the release of PX. Cyclodextrin complexation increased the PX concentration gradient over the semipermeable membrane, resulting in an increased PX flux. The retarded diffusion of PX to the membrane interface decreased the PX flux values of the ternary complexes.     

低渗透裂缝性砂岩油藏渗吸机理及其数学模型

研究了低渗透裂缝性砂岩油藏的渗吸机理,分析了各种因素对自发渗吸的影响.对低渗透岩心的自发渗吸实验数据进行了归一化处理,改进了三重指数函数模型,使之更好地符合低渗透裂缝性砂岩油藏的自发渗吸特性.利用常规室内水驱油实验和核磁共振成像技术,研究了驱替条件下渗吸的问题.提出了在低渗透岩心水驱油过程中存在最佳渗流速度;并分析了在水驱油过程中的渗吸机理,为低渗透裂缝性砂岩油藏的水驱油开发提供理论指导.     

头孢菌素C钠溶液膜分离工艺的研究

以头孢菌素C钠盐的水溶液为对象设计实验,考察了板式膜的膜通量和溶质透过率的衰减现象,以及钠离子对膜的影响.研究结果表明,衰减的主要原因是膜表面吸附钠离子以及在膜表面形成浓差极化层;原液浓度影响膜通量是间接的;此外在宏观表现如原液浓度高、膜的处理量大、处理时间长和钠离子含量高都将加剧膜通量和溶质透过率的衰减.在实际应用中需考虑这些因素.     

水蒸气在高分子膜中的透过行为与气体膜法脱湿

在气体膜分离中,水蒸气的分离过程比其它非凝聚性气体更复杂,因为水分子可以通过氢键和聚合物链节中极性基团发生作用,使聚合物被溶胀、塑化;水分子自身可通过分子间氢键聚集成簇,这些因素导致了水分子在膜中的透过行为不再符合其它气体的透过规律.水蒸气在极性高分子膜中较高的渗透能力会在膜的下游侧产生浓差极化现象,消除浓差极化现象才能使水蒸气透过正常进行.膜材料的选择要权衡亲水性和疏水性,共混和嵌段共聚是解决这一矛盾的有效手段.水蒸气在高分子膜中的较高透过能力使其用于气体膜法脱湿成为可能.现以压缩空气膜法脱湿为例,介绍了影响膜法脱湿效率的主要因素,也介绍了气体膜法脱湿的其它应用领域.     

用减压膜蒸馏淡化罗布泊地下苦咸水

考察了减压膜蒸馏过程淡化高浓度盐溶液过程中温度、浓度、真空度对膜通量的影响,结果表明:膜的渗透通量与温度的倒数呈指数关系,高真空度下膜的通量与膜两侧水蒸气分压平方根的差呈直线关系,这种直线关系说明了水蒸气在膜孔内的传质过程是以扩散为主;当盐溶液浓度达到一定量时,浓度的增大对膜通量的影响较小.将减压膜蒸馏应用于新疆罗布泊地区地下苦咸水的淡化处理,可获得馏出液电导率均小于10μS/cm的较好效果.     

氧透双油泵的自动控制

本文以浙江中控公司DCS系统组态软件AdvanTrolPro（V2．5）为例，介绍实现氧透双油泵自动控制为目的的组态思路和方法。     

无基元高混合熵合金形成固溶体结构三原则

无基元高混合熵合金是由五种以上主元素构成，具有很高的混合熵。通过对已发表无基元高混合熵合金数据的分析，初步得出无基元高混合熵合金形成固溶体的一般规律：1五种以上主元素；2最大原子半径差小于12％；3舍金混合焓介于-40到10KJ／mol。     

Hydrogen permeability of multiphase V-Ti-Ni metallic membranes

Development of advanced hydrogen separation membranes in support of hydrogen production processes such as coal gasification and as front end gas purifiers for fuel cell based system is paramount to the successful implementation of a national hydrogen economy. Current generation metallic hydrogen separation membranes are based on Pd-alloys. Although the technology has proven to be successful, at issue is the high cost of palladium. Evaluation of non-noble metal based dense metallic separation membranes is currently receiving national and international attention. The focal point of the reported work was to evaluate a Group 5A-Ta, Nb, V-based alloy with respect to microstructural features and hydrogen permeability. Electrochemical hydrogen permeation testing of the V-Ti-Ni alloy is reported herein and compared to pure Pd measurements recorded as part of this same study. The V-Ti-Ni was demonstrated to have a steady-state hydrogen permeation rate an order of magnitude higher than the pure Pd material in testing conducted at 22 °C.     

In‐Depth Study of Mass Transfer in Nanoporous Materials by Micro‐Imaging

The first application of interference microscopy to monitoring mass transfer in nanoporous materials dates back to late 1970s when Caro and colleagues reported results of investigations of water uptake by LTA type zeolites. It was, however, not before the beginning of the new millennium that the developments in both the measuring technique and computational power have enabled the recording of transient guest profiles during molecular uptake and release under well‐defined conditions, leading to the establishment of a novel access to diffusion studies, now referred to as micro‐imaging. In the present contribution, the thus accessible novel type of information is illustrated by an in‐depth analysis of the uptake kinetics of methanol in an all‐silica ferrierite. In particular, two remarkable experimental findings are reported, which may be tracked back to their microstructural and/or microdynamic origin, namely a pronounced asymmetry in the transient concentration profiles and a slowing down of guest uptake with increasing temperature.