Preparation,optimization, and voltammetric characteristics of poly(o‐phenylenediamine) film as a dopamine‐selective polymeric membrane

Poly(o‐phenylenediamine) films were electrochemically prepared on gold electrodes from the corresponding monomer in an aqueous solution at a constant potential. The polymeric films prepared in this one‐step procedure were found to be thin and insoluble in the aqueous solution. Cyclic and differential pulse voltammetric techniques were used to examine the permeation properties of ascorbic acid and dopamine at the resultant polymeric film electrode. Then, the effects of the chemical and electrochemical variables (e.g., film thickness, polymerization potential, concentrations of monomer and electrolyte) on the permselectivity characteristics of the polymeric film were systematically investigated and the optimal values for each parameter were determined. Furthermore, it was found that the optimized polymer electrode was found to be stable for the successive runs. As a result, it is claimed that poly(o‐phenylenediamine) film can be used as a dopamine‐selective polymeric membrane. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 327–332, 2001     

分子模拟在聚合物膜研究中的应用

简要回顾了近15年来分子模拟在各种聚合物膜研究中的应用,分析了它为宏观实验现象提供的新解释以及给聚合物膜的改性和设计研究工作带来的新思路,同时也对当前计算条件下模拟中存在的问题进行了探讨。     

膜乳化法原理及其制备单分散高分子微球的进展

介绍了膜乳化法的原理及其影响因素,由膜乳化法制备的单分散高分子微球具备粒径均一、分布可控等特点;综述了由膜乳化法制备的单分散高分子微球在化妆品、生物医药、化工等相关领域的应用研究进展.     

无机膜与有机膜的材料特点与工艺性能对比分析

概述了无机膜和有机膜的概念类别、制备方法、应用领域、膜性能参数和膜清洗方法,通过对比分析可知,无机膜在装填密度、制作成本及工业化应用等方面有待优化,但在膜耐污能力、运行稳定性和膜再生性能等方面更具技术优势和应用前景.     

Synthesis, Characterization anc Dopamine Selectivity of 1,4-bis(3-aminopropyl)piperazine—Containing Polyimide

Summary A novel polyimide prepared from 1,4-bis(3-aminopropyl) piperazine and pyromellitic dianhydride (PMDA) was characterized by thermal, FTIR, GPC and microanalysis techniques. Thermal properties of the polyimide were evaluated by differential scanning calorimetry (DSC), differential thermal analysis (DTA) and thermogravimetry (TGA). Moreover, platinum electrodes were covered with this polyimide and permeation properties of the resulting polyimide-coated electrodes to dopamine and ascorbic acid were examined by electrochemical method. On the basis of the permselectivity data obtained, it was found that the polyimide-coated electrode exhibited selective permeation for dopamine while blocking ascorbic acid.     

Modeling a dense polymeric catalytic membrane reactor with plug flow pattern

A theoretical study on a tubular membrane reactor assuming isothermal operation, plug flow pattern and using a dense polymeric catalytic membrane is performed. The reactor conversion for an equilibrium gas-phase reaction generically represented by AB is analyzed, considering the influence of the product’s sorption and diffusion coefficients. It is concluded that the conversion of such a reaction can be significantly improved when the overall diffusion coefficient of the reaction product is higher than the reactant’s one and/or the overall sorption coefficient is lower, and for Thiele modulus and contact time values over a threshold. Though a sorption coefficient of the reaction product lower than that of the reactant may leads to a conversion enhancement higher than that one obtained when the reaction product diffusion coefficient is higher than that of the reactant, the contact time value for the maximum conversion is much higher in the first case. In this way, a higher diffusion coefficient for the reaction product should be generally preferable, because it leads to a lower reactor size. The performance of a dense polymeric catalytic membrane reactor depends in a different way on both sorption and diffusion coefficients of reactants and products and then a study of such a system cannot be based only on their own permeabilities. Favorable combinations of diffusion and sorption coefficients can affect positively the reactor’s conversion.     

Preparation and properties of polybenzidine film-coated electrode as an H2O2 selective polymeric material

By means of electrochemical polymerization, polybenzidine-modified electrodes were prepared in an aqueous monomer solution at a potential of 0.7 V versus Ag/AgCl. The permselective character of the polybenzidine electrode prepared in a one-step procedure was examined for electroactive (ascorbic acid, oxalic acid, and hydrogen peroxide) and nonelectroactive (lactose, sucrose, and urea) species. Influence of the various parameters on the permselective properties of the polybenzidine membrane was systematically investigated and the optimal values for these parameters were determined. It has been found that polybenzidine membrane showed selective permeation for hydrogen peroxide while blocking the permeation of electroactive and nonelectroactive interferents through film. In brief, it is claimed that this polybenzidine film can be used as a coating material to prevent interferences in electrochemical biosensor applications. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 70: 2227–2234, 1998     

膜生物反应器中污泥EPS的提取方法

采用七种方法（热、酸、碱处理等）提取MBR（Membrane Bioreactor）中污泥EPS（extracellular polymeric substances）,研究了这些方法对于污泥EPS的最佳提取条件。在综合考虑各种方法的精确性、操作简易度、提取效果、对污泥细胞的破坏程度后,确定EDTA二钠提取（浓度2%,3h）和热提取（80℃,45min）是最简便有效的两种提取方法。NaOH提取（1mol.L^-1,2h）对污泥细胞具有很大的破坏作用,投加甲醛（浓度2%,2h）之后提取核酸含量减少了21.5%,降低了NaOH溶液提取对于细胞的破坏作用。     

高分散聚合法制备新型两性包被絮凝剂

采用分散聚合工艺,以丙烯酰胺、2-丙烯酰胺基-2-甲基丙磺酸和二甲基二烯丙基氯化铵3种单体为原料,合成了6个不同黏均相对分子质量的共聚物,探讨了引发剂和稳定剂对特性黏数的影响以及反应时间和转化率的关系,并对不同黏均相对分子质量的共聚物的絮凝能力、抑制性以及抗温性能进行了测定和表征。结果表明,黏均相对分子量和特性黏数随引发剂和稳定剂用量的增加先增大后减小;转化率随反应时间呈饱和曲线特征;其中3#共聚物清液体积为330 mL,页岩回收率65%(120℃)和57%(150℃),岩心膨胀率为128%,黏度保留率高,可以在钻井液和完井液中作为一种良好的絮凝剂。     

Preparation of monodispersed polymeric microspheres for toner particles by the shirasu porous glass membrane emulsification technique

This investigation describes the experiment directed toward the production of monodispersed toner particles by suspension polymerization. That is, relatively monodispersed poly(styrene-co-divinylbenzene) microspheres containing electrifying additives were successfully prepared by suspension polymerization employing the Shirasu Porous Glass (SPG) membrane emulsification technique. The diameter distribution of the dispersed droplets prepared with an SPG membrane module was fairly narrow, compared with that prepared with a conventional mechanical homogenizer. The effect of Sumiplast Blue S as coloring matter and E-81 as charge control agent on the triboelectric discharging properties of prepared polymeric microspheres was studied. The addition of electrifying additives strongly affected the triboelectric discharging property. It was consequently clarified that a small amount of electrifying additives added raised the electrostatic capacity of polymeric microspheres. However, a further addition reduced the triboelectric discharge of polymeric microspheres. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 64: 1107–1113, 1997     

Synthesis,characterization of phosphine oxide-containing polyimides and their use as selective membrane for dopamine

Tris-(p-aminophenoxy)phosphineoxide, t-APPO, was prepared from 4-nitrophenol and POCl₃, followed by hydrogenation. A series of polyimides prepared from t-APPO and the corresponding dianhydrides by two-stage polycondensation method was characterized by Fourier Transform Infrared Spectrometer (FTIR), GPC, thermal analysis and physical methods. Moreover, in order to check the permeation properties of the resulting polyimide film, the selectivity of the polyimide-coated electrode toward electroactive species (ascorbic acid and dopamine) was examined by means of cyclic voltammetry (CV), differential pulse voltammetry (DPV) and time-base amperometric measurement (TB) techniques. As a result, it has been found that polyimide electrode showed selective permeation for dopamine while blocking the permeation of ascorbic acid through film. Therefore, it has been claimed that phosphine oxide-containing polyimide electrode can be used as a dopamine-selective membrane in the presence of ascorbic acid.     

CO2/CH4高分子气体分离膜材料研究进展

气体膜分离法正在成为分离CO2/CH4体系的一项重要技术。概括介绍了该领域国内外的主要高分子膜材料的研究进展,重点介绍了聚酰亚胺膜和促进传递膜材料,并提出了膜材料的改进方向,以期为制得更好的膜提供帮助。     

Processing of tocopherol and FA systems using a nonporous denser polymeric membrane

Tocopherols permeated preferentially over oleic acid in model systems and over oleic acid and other oil constituents during processing of soy deodorizer distillate (DOD) when using nonporous denser polymeric membranes (i.e., denser than reverse osmosis membranes). This observation was unexpected, since the separation in a denser membrane is generally based on a solution-diffusion mechanism. That tocopherols are less polar than oleic acid appears to have facilitated the preferential permeation of tocopherols through the hydrophobic membrane. Selectivity of the membrane for tocopherols improved with esterified soy DOD. The presence of FAME decreased the viscosity of the feed and thereby increased convective flow, which in turn improved permeate flux. FAME appeared to have exerted positive coupling effects with tocopherols, having better selectivity in spite of the greater solubility of FAME in the membrane material. Membrane selectivity for tocopherols improved upon dilution of the feed material with hexane, perhaps owing to greater solubility of tocopherols in hexane (nonpolar) than other feed constituents.     

Preparation,characterization, and permeation property of a liquid crystal/PDMS membrane material

By introducing the ordered and flowing liquid crystalline groups into polymeric membranes, a novel liquid crystal/polydimethylsiloxane (LC/PDMS) membrane material is synthesized with PDMS containing vinyl group, polymethylhydrosiloxane and cholesteric LC as matrix materials. The chemical structure, LC behaviors and mechanical performance of the LC/PDMS crosslinked membranes are characterized by using FTIR, differential scanning calorimetry (DSC), and polarized light microscopy with a hot stage. Some factors on permeability and permselectivity for carbon dioxide and nitrogen gas are also examined. These results suggest that the membrane‐forming property and permeation properties of the crosslinked membranes are obviously enhanced due to the introduction of the LC groups into PDMS and crosslinking reaction in the preparation process. At pressure difference of 0.1 MPa and testing temperature of 40°C, the permeability coefficient for carbon dioxide and ideal separation factor for carbon dioxide and nitrogen are up to 4667 Barrer and 24.0, respectively. In addition, the incorporation of LC containing unsaturated linkage has the potential for further modification reactions such as grafting and crosslinking. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

高分子表面活性剂对细乳液聚合的影响

通过分析细乳液聚合过程中的单体乳液稳定性、聚合反应动力学以及聚合所得乳胶粒的特性,讨论了高分子表面活性剂对细乳液聚合的影响,并与普通低分子表面活性剂进行了比较。     

Propyne hydrogenation in a continuous polymeric catalytic membrane reactor

Propyne hydrogenation was studied in a continuous polymeric catalytic membrane reactor (pCMR), both experimentally and theoretically. It was used a poly(dimethylsiloxane) (PDMS) composite membrane with an average thickness of , loaded with 5 wt% of 9 nm diameter Pd clusters. The reaction was conducted at 308 K and several feed compositions at a fixed flow rate were tested.The mathematical model proposed includes the mass balances to the retentate and permeate chambers and the mass balance and transport kinetics through the catalytic membrane. The pCMR model also considers a reaction rate equation composed of two terms: the propyne to propylene and the propylene to propane hydrogenations. The selectivity between these two reactions is described by the bicomponent adsorption of propyne and propylene obtained by the IAST model (thermodynamic selectivity). The proposed model represents quite well the experimental data regarding the flow rates and mixture compositions of the permeate and retentate streams.     

Factors affecting the adsorption of cationic dyes on polymeric hydrogels prepared by gamma irradiation

The adsorption of the cationic dyes Rhodamine B (RB) and Crystal Violet (CV) on polyacrylamide/poly(acrylic acid) (poly(AAm/AAc), 25:25 % weightwise) and polyacrylamide/poly(sodium acrylate) (poly(AAm/AAcNa), 25:25 % weightwise) hydrogels was studied, employing the Langmuir and Freundlich isotherms. The results of swelling tests at pH 5.5 indicate that poly(AAm/AAcNa) hydrogel shows maximum percentage swelling (%S) was 4400 %. Moreover, the results show that the adsorption capacity is pH‐ and concentration‐dependent. At pH >5 adsorption of RB and CV increases due to ionization of ? COOH and ? COONa groups of (poly(AAm/AAc) and (poly(AAm/AAcNa) and interactions with the cationic groups of the dyes. However, at pH lower than 5, adsorption is still high, which can be explained by considering the formation of hydrogen bonds between the amino groups of the dyes and the ? COOH groups of the polymeric hydrogels. Moreover, the kinetics of adsorption follows a first‐order equation. Furthermore, scanning electron microscopy (SEM) micrographs of polymeric hydrogels doped with CV and RB have morphological differences from the pure form. Our data show that Rhodamine B adsorbs more efficiently on both polyacrylamide/poly(acrylic acid) and polyacrylamide/poly(sodium acrylate) hydrogels than CV. Copyright © 2004 Society of Chemical Industry     

Preparation of mineral source water from deep sea water: Reduction of sulfate ion using selemion ASV membrane

Adopting a laboratory‐scaled electrodialysis (ED) process, we investigate the performance of a monovalent anion exchange permselective membrane in the reduction of the concentration of sulfate ions during the production of mineral source water from deep sea water (DSW). The dependence of the separation efficiency of anions on the operating time and the applied DC voltage is investigated based on a brine having salinity of about 15% prepared from DSW. The experimental results reveal that if the applied DC voltage is high, the change in the liquid volume during ED is dominated by the ions transported and the effect of electroosmosis. In addition, the amount of chloride ions transported correlates roughly linearly with the operating time, and the transport of sulfate ions is found to be blocked by chloride ions, presumably because of that the pore size of the permselective layer is close to the size of sulfate ions. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

Investigation on the enhancement of solvent-resistant nanofiltration membrane performance utilizing PDA-UiO-66@CNT as an interlayer

With the growing complexity of separation systems, the application of thin film composite nanofiltration (TFN) membranes in organic solvent separation faces numerous challenges. To augment its solvent stability, an in-situ constructed dopamine hydrogel doped with UiO-66@CNT was developed as an intermediate layer on a polyetherimide (PEI) ultrafiltration membrane. Subsequent interfacial polymerization on this interlayer led to the formation of a solvent-resistant nanofiltration membrane with a vast covalent bond structure, large specific surface area, and enhanced hydrophilicity. Our findings revealed that when the CNT loading in the UiO-66@CNT composite nanoparticles was 2 wt%, the TFN-U₂C₂ membrane exhibited a maximum pure water flux of 126.32 L/(m²·h) and a methanol flux of 45.45 L/(m²·h). The rejection rates for Congo red aqueous and methanol solutions were 96.88% and 92.14%, respectively. The membrane also demonstrated commendable anti-fouling properties. Remarkably, even after 48 h of immersion in various organic solvents, the membrane retained its morphology and separation efficiency. Compared to the TFN-U₂ membrane without CNT addition, the enhancement in separation performance was considerably significant. Hence, this membrane has significant potential for application in treatment of wastewater containing organic solvents and is promising in related fields.     

填料对一体式膜生物反应器运行效能的影响

进行了组合式膜生物反应器(CMBR)和一体式膜生物反应器(SMBR)处理生活污水的试验研究,以考察填料对处理效果的影响及减缓膜污染方面的作用。在稳定期,CMBR对COD的平均去除率为96.7%,SMBR为95.9%,对NH3—N的去除率分别为95.6%和94.9%,试验结果表明,填料的添加对反应器COD和NH3—N的去除效果影响不大,但能有效增强反应器对总氮的去除,去除率从54.5%提高到67.5%;经102 d连续运行,CMBR膜组件清洗次数少于SMBR,说明添加填料不仅提高了膜生物反应器(MBR)的处理效果,而且相对有效地减缓了膜阻力升高的速度;单位膜面积上胞外聚合物(EPS)的面密度与2个膜生物反应器过膜压力随运行时间的变化规律基本一致,CMBR和SMBR中膜阻力与单位膜面积上EPS的面密度正相关,证明EPS对膜污染有着重要的影响。