界面聚合法制备聚哌嗪酰胺复合纳滤膜

以聚醚砜超滤膜为基膜,哌嗪(PIP)为水相单体,均苯三甲酰氯(TMC)为有机相单体,采用界面聚合法制备了复合纳滤膜,扫描电镜、表层的红外分析结果表明在基膜表面聚合了一层聚酰胺膜,膜性能测定结果表明膜表面荷负电,对不同无机盐的截留率为Na2SO4MgSO4MgCl2NaCl。界面聚合条件对膜性能的影响表明,最佳聚合条件为:PIP浓度0.5%～2%,TMC浓度0.15wt%～0.75wt%,聚合时间≥1min,热处理温度60℃～80℃,时间15 min左右。     

PES中空纤维复合纳滤膜的制备

采用界面聚合法制备聚醚砜（PES）中空纤维复合纳滤（NF）膜,讨论了制备条件对PES中空纤维复合NF膜性能的影响。实验结果表明,聚合反应时间、均苯三甲酰氯浓度、哌嗪浓度和酸吸收剂三乙胺浓度对复合NF膜性能有显著影响,同时二次反应能够提高复合NF膜的截留率,对2g／L的Na2SO4截留率可达到99．2％。     

电化学聚合漆酚铜配合物催化引发醋酸乙烯酯聚合的研究

将电化学聚合方法得到的聚合漆酚 (EPU)与氯化铜异丙醇溶液作用生成电化学聚合漆酚铜配合物(EPU Cu2 + ) .采用顺磁共振波谱 (ESR)、红外光谱 (FT IR)、XPS光电子能谱、原子发射光谱 (AES)、元素分析及AES等手段进行表征 ,确定该配合物的结构即每个铜离子与EPU分子中二个链节单元的羟基发生配位 .配合物中铜含量达 8 6 3% .实验表明 ,电化学聚合漆酚铜 (EPU Cu2 + )配合物膜在室温下的Na2 SO3水体系 (pH =7)中能催化引发醋酸乙烯酯 (VAc)按自由基加聚反应历程进行聚合 .讨论了温度、Na2 SO3浓度、VAc浓度和EPU Cu2 + 膜用量对聚合速率、诱导时间的影响 ,求得聚合速率的表达式Rp=0 0 7e- 2 82 5 RT[VAc]1 54[Na2 SO3]0 5,实验结果表明 ,EPU Cu2 + 配合物膜催化引发醋酸乙烯酯 (VAc)聚合的诱导期为 12 2s ,反应 2 4h后PVAc得率为79% , Mw =1 2 6× 10 6 , Mn=2 6 3× 10 5,多分散性系数为 4 79.     

不同电解质溶液对聚吡咯修饰膜性质的影响

以对甲基苯磺酸钠(p-TSNa)为掺杂剂在不锈钢电极表面恒电位合成聚吡咯(PPy)修饰膜, 采用循环伏安法在-1.6 - 0.8 V大范围扫描研究了修饰膜在H2SO4、Na2SO4、NaOH电解质溶液中的氧化还原行为. 结果表明, 在H2SO4溶液中, 以H+的脱出(氧化)/嵌入(还原)为特征, 并发现聚吡咯在酸性溶液中所特有的质子还原峰. 在Na2SO4和NaOH溶液中, 以Na+的脱出(氧化)/嵌入(还原)峰为特征. FT-IR吸收光谱显示, 经NaOH处理后, 聚吡咯膜的长共轭结构被完全破坏, 而经H2SO4和Na2SO4处后, 膜的共轭结构未发生变化.     

单体结构对聚酰胺类复合膜分离性能的影响

采用间苯二甲酰氯、均苯三甲酰氯、均苯四甲酰氯分别与间苯二胺、乙二胺、哌嗪在耐高温杂萘联苯聚醚砜酮(PPESK)超滤膜表面进行界面聚合,制备了7种具有不同功能层结构的新型超薄复合膜.采用红外、X射线衍射、原子力显微镜等测试手段对复合膜结构进行表征,测试了7种复合膜对0·2%的Na2SO4水溶液,0·2%NaCl水溶液的分离性能,分析了单体结构与复合膜分离性能的关系.     

纤维素膜的制备及性能研究北大核心CSCD

采用新型纤维素溶解体系NaOH/硫脲/尿素体系作为溶剂,对纤维素进行溶解、过滤、脱泡,得到澄清的纤维素溶液,然后通过H2SO4、HOAC(CH3COOH)、H2SO4/Na2SO4等不同的凝固浴制备出纤维素膜,采用XRD、SEM和强力拉伸测试等方法对纤维素膜进行表征得出纤维素膜的最佳凝固温度为20℃,不同凝固浴的最佳浓度及凝固时间分别是H2SO4-5%-3min,HOAC-9%-3min,H2SO4/Na2SO4-7%/9%-5min。其中,最佳的凝固浴及其凝固条件为20℃,H2SO4/Na2SO4-7%/9%-5min。此时纤维素膜具有均匀致密的孔洞结构,其拉伸强度及断裂伸长率分别为166.2MPa-13.5%。     

中性介质中铜缓蚀剂的成膜过程

使用光电化学与电化学石英晶体微天平联用（PECQCM）技术对中性介质铜缓蚀剂成膜过程进行了现场研究．结果表明，在中性Na2SO4溶液中钝化型缓蚀剂Na2OrO4对Cu成膜生长有抛物线规律，而由于Cl-的影响，在中性NaCl溶液中，该缓蚀剂膜生长曲线为折线型．沉淀型缓蚀剂Na2SiO3在Na2SO4溶液中的铜晶振电极上不成膜，而在NaCl溶液中可成膜．     

TiO_2/Na_2SO_3体系中日光催化聚合甲基丙烯酸甲酯的研究

在密闭空气和日光连续照射下 ,考察了TiO2 Na2 SO3 体系中MMA的聚合行为 ,结果显示 ,在TiO2 的零电荷点处 ,日光可引发聚合甲基丙烯酸甲酯 ,诱导期为 2～ 15min ,主要受pH的控制 .当 [TiO2 ]=(5 .0～ 7.0 )× 10 - 5mol·L- 1 ,[Na2 SO3]=(1.0～ 1.5 6 )× 10 - 3 mol·L- 1 ,[MMA]=(3.74～ 10 .7)× 10 - 2 mol·L- 1 时 ,表观聚合速率Rp=k·e- 1 1 4 .80 0 RT·[MMA]0 .94[IA]0 .50 [Na2 SO3]0 .55[TiO2 ]1 .0 6 ,所得聚合物平均分子量为 12 0× 10 5,最高产率达 95 % ,聚合按自由基机理进行     

Na2B4O7-Na2SO4-NaCl-H2O四元体系288K相平衡研究

采用等温溶解平衡法研究了四元体系Na2B4O7-Na2SO4-NaCl-H2O在288 K的相平衡关系,测定了平衡液相的溶解度及其密度。由研究结果知该四元体系为简单共饱和型,无复盐及固溶体形成。根据实验数据绘制了相应的相图。相图中有一个共饱点,三条单变曲线,三个结晶区平衡固相分别为:Na2B4O7·10H2O,Na2SO4·10H2O和NaCl。实验结果表明NaCl对Na2B4O7和Na2SO4有盐析作用,并简要讨论了实验结果。     

CuO/Al2O3吸附SO2后氢再生及一体化回收硫磺

考察了添加Na助剂对CuO/Al2O3 的H2再生过程、硫磺产量及后续脱SO2过程活性的影响。结果表明,400℃再生温度下Na助剂添加后,CuO/Al2O3吸附剂的H2再生循环过程的硫磺产量及后续脱SO2过程硫容均变为添加前的1.3倍。Na助剂的添加明显增大吸附剂上载体Al2O3的硫化程度;且在Cu相和Na相共同存在情况下,吸附剂上生成的部分物质Al2(SO4)3在400℃以下即可被还原再生,从而明显提高了H2再生过程的硫磺产量和后续脱SO2硫容。     

Nanofiltration membranes synthesized from hyperbranched polyethyleneimine

Four nanofiltration membranes, two negatively and two positively charged, were fabricated by interfacial polymerization. Three different amines, ethylenediamine (EDA), diethylenetriamine (DETA), and hyperbranched polyethyleneimine (PEI) were selected to react with two acyl chlorides, trimesoyl chloride (TMC) and terephthaloyl chloride (TPC). The two membranes containing hyperbranched PEI, PEI/TPC and PEI/TMC, are positively charged at the operational pH. But the other two membranes, EDA/TMC and DETA/TMC, are negatively charged. It is found that the two PEI membranes own special rejection characters during nanofiltration. The PEI/TPC membrane has a similar pore size to the EDA/TMC membrane but owns simultaneously the higher salt rejection and permeation flux. The PEI/TMC has a pore size as large as 1.5 nm and still has a higher NaCl rejection than the EDA/TMC membrane of which the pore size as small as 0.43 nm. We consider that the special rejection characters are derived from the special structure of PEI. The hyperbranched structure allows some of the charged amine groups drifting inside the pores and interacting with the ions in the pathway. The drifting amines increase salt rejection but have little effect on water permeation. It implies that a high flux and high rejection membrane for desalting can be obtained by attaching freely rotating charged groups.     

用流动电位法表征纳滤膜的结构及性能

利用测量流动电位的方法考察了纳滤膜的表面电学性能对纳滤膜的截留性能的影响.首先,采用不同功能层材料制备了复合纳滤(NF)膜,考察功能层的交联时间、单体结构等对表面电性能的影响,研究纳滤膜对不同无机盐的选择截留性能与表面电性能的关系.通过流动电位法测定纳滤膜的表面电学参数,如流动电位(ΔE)、zeta电位(ζ)和表面电荷密度(σd).实验表明,这些电学参数的变化与功能层交联时间和纳滤膜截留率的变化一致,在交联时间为45 s时,3种电学参数的绝对值均最大,而纳滤膜对无机盐的截留率也最大.复合纳滤膜zeta电位的绝对值(|ζ|)按照Na2SO4>MgSO4>MgCl2变化,同截留率的变化相同.带侧基单体交联后得到的纳滤膜的表面电性能参数的绝对值小于不带侧基单体的.因此,流动电位法可用于研究复合纳滤膜的截留机理和功能层结构.     

Photoactivity Characteristics of a Biodevice Using Primary Photosynthetic Reaction Centers

Films with alternating layers of thylakoid membrane from the cyanobacterium Spirulina platensis and the positively charged polyion poly(ethylenimine) (PEI) were prepared by means of alternate electrostatic layer‐by‐layer assembly. The thylakoid membrane/PEI bilayers were functionally and structurally characterized by visible spectra, electrochemical methods and SEM techniques, respectively. The films deposited onto gold electrodes were molecularly smooth and consistent with thylakoid membrane/PEI bilayers as observed by SEM. The photoactivity of the thylakoid membrane/PEI assembly was dependent on thickness of the film that increased with the number of bilayers. There was an obvious difference in the current responses of 1‐ and 5‐bilayer thylakoid membrane/PEI films under illumination. The photosynthetic electron transfer process in the thylakoid membrane/PEI single‐bilayer film was demonstrated by an inhibition of the photoactivity by herbicide. Biodevices for the detection of phytotoxicity were constructed using the isolated thylakoid membrane from chloroplast as biosensing elements by means of electrostatic layer‐by‐layer assembly.     

Membrane potential across anion-exchange membranes in acidic solution system

The membrane potential across anion-exchange membranes in H2SO4 and Na2SO4 solutions was measured, and the experimental results were fitted to the theory in the 2-1 electrolyte system based on the Donnan equilibrium and the Nernst-Planck flux equations. For the Na2SO4 solution, the Donnan potential makes a significant contribution to the membrane potential, but for the H2SO4 solution, the diffusion potential significantly contributes to the membrane potential. The diffusion potential has a greater contribution to the membrane potential across AEM-2 with a high water content than that across AEM-1. These results suggest that a proton with a high mobility can move without substantial influence of electrostatic interaction in a positively charged membrane.     

Reversible switching of protein uptake and release at polyelectrolyte multilayers detected by ATR-FTIR spectroscopy

The reversible switching of uptake and release of the proteins lysozyme (LYZ, IEP = 11.1) and human serum albumin (HSA, IEP = 4.8) at the surface attached polyelectrolyte multilayer (PEM) consisting of poly(ethylene-imine) (PEI) and poly(acrylic acid) (PAC) is shown. Protein adsorption could be switched by pH setting due to electrostatic interaction. Adsorption of positively charged LYZ at PEM-6 took place at pH = 7.3, where the outermost PAC layer was negatively charged. Complete desorption was obtained at pH = 4, where the outermost PAC layer was neutral. Additionally the charge state of the last adsorbed PAC layer in dependence of the pH of the medium could be determined in the ATR-FTIR difference spectra by the ν(COO⁻) and ν(C=O) band due to carboxylate and carboxylic acid groups. Adsorption of negatively charged HSA at PEM-7 was achieved at pH = 7.3, where the outermost PEI layer was positively charged. Part desorption was obtained at pH = 10, where the outermost PEI layer was neutral. PEM of PEI/PAC may be used for the development of bioactive and bionert materials and protein sensors.     

Fast and effective paper based sensor for self-diagnosis of bacterial vaginosis

In this contribution we present a sensitive colorimetric bioactive paper fabricated to determine sialidase-related diseases like bacterial vaginosis (BV) in a one-step and dry format spot assay with fast response and good storage stability. The paper was prepared by three simple steps. The first step involves preparation of poly(ethyleneimine) (PEI) microcapsules, the second step is to incubate positively charged microcapsules in negatively charged 5-bromo-4-chloro-3-indolyl-a-d-N-acetylneuraminic acid (BCIN) solution, a color enhancer nitro blue tetrazolium (NBT), and in the third step, paper was fabricated by incorporating incubated microcapsules into paper pulp. This paper changes color from white to dark purple in the presence of sialidase in as little as 6 min, and color could be enhanced with increased length of reaction time. In this reaction system, BCIN was the substrate for sialidase, NBT was the color enhancer, and PEI microcapsules acted as catalyst. The loading efficiency of BCIN was about 22.2%, and filtered BCIN solution could be reused for the next fabrication.     

Protein nanotubes comprised of an alternate layer-by-layer assembly using a polycation as an electrostatic glue

We present the synthesis and structure of various protein nanotubes comprised of an alternate layer-by-layer (LbL) assembly using a polycation as an electrostatic glue. The nanotubes were fabricated by sequential LbL depositions of positively charged polycations and negatively charged proteins into a porous polycarbonate (PC) membrane, followed by release of the cylindrical core by quick dissolution of the template with CH(2)Cl(2). This procedure provides a variety of protein nanotubes without interlayer cross-linking. The three-cycle depositions of poly-L-arginine (PLA) and human serum albumin (HSA, M(w)=66.5 kDa) into the porous PC template (pore diameter, D(p)=400 nm) yielded well-defined (PLA/HSA)(3) nanotubes with an outer diameter of 419+/-29 nm and a wall thickness of 46+/-8 nm, revealed by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) observations. The outer diameter of the tubules can be controlled by the pore size of the template (200-800 nm), whereas the wall thickness is always constant, independent of the D(p) value. The (PEI/HSA)(3) (PEI: polyethylenimine) nanotubes showed a slightly thin wall of 39+/-5 nm. CD spectra of the multilayered (PEI/HSA)(n) film on a flat quartz plate suggested that the secondary structure of HSA between the polycations was almost the same as that in aqueous solution. The three-cycle LbL depositions of PLA and ferritin (M(w)=460 kDa) or myoglobin (Mb, M(w)=1.7 kDa) into the porous PC membrane also gave cylindrical hollow structures. The wall thickness of the (PLA/ferritin)(3) and (PLA/Mb)(3) nanotubes were 55+/-5 nm and 31+/-4 nm; it depends on the globular size of the protein (ferritin>HSA>Mb). The individual ferritin molecule was clearly seen in the tubular walls by SEM and TEM measurements.     

Polyamide Nanofiltration Membrane from Surfactant-assembly Regulated Interfacial Polymerization of 2-Methylpiperazine for Divalent Cations Removal

Removal of metal ions from water can not only alleviate the scaling problem of domestic and industrial water, but also solve the water safety problem caused by heavy metal ion pollution. Here, we fabricate a positively charged nanofiltration membrane via surfactant-assembly regulated interfacial polymerization(SARIP) of 2-methylpiperazine(MPIP) and trimesoyl chloride(TMC). Due to the existence of methyl substituent, MPIP has lower reactive activity than piperazine(PIP) but stronger affinity to hexane, resulting in a nanofiltration(NF) membrane with an opposite surface charge and a loose polyamide active layer. Interestingly, with the help of sodium dodecyl sulfate(SDS) assembly at the water/hexane, the reactivity between MPIP and TMC was obviously increased and caused in turn the formation of a positively charged polyamide active layer with a smaller pore size, as well as with a narrower pore size distribution. The resulting membrane shows a highly efficient removal of divalent cations from water, of which the rejections of MgCl₂, CoCl₂ and NiCl₂ are higher than 98.8%, 98.0% and 98.0%, respectively, which are better than those of most of other positively charged NF membranes reported in literatures.     

In situ study of diffusion and interaction of water and mono- or divalent anions in a positively charged membrane using two-dimensional correlation FT-IR/attenuated total reflection spectroscopy

Two-dimensional (2D) correlation analysis based on time-resolved FT-IR/attenuated total reflection (ATR) spectroscopy has been used to study the diffusion behavior of water and mono- or divalent anions in the positively charged membranes of different charge density. In 2D FT-IR/ATR spectra, the splitting of the water delta(OH) bending band in the spectral range 1700-1500 cm-1 indicates that there are three different states of water in the positively charged membrane, that is, the water molecules forming strong or weak hydrogen bonds with hydrophilic groups of the membrane and water molecularly dispersed with weaker hydrogen bonds. The wavenumber difference of the delta(OH) band in the low- and high-charge-density membrane indicates that water molecules form much stronger hydrogen bonds with hydrophilic groups in the high-charge-density membrane. The sequential order of the three water bands intensity changes shows that, in the process of water diffusion into the high-charge-density membrane, the hydrogen-bonding interaction between hydrophilic groups of the membrane and water molecules takes place gradually due to the highly cross-linked network structure of the membrane; in the process of water diffusion into the low-charge-density membrane, the strong hydrogen-bonding interaction between hydrophilic groups of the membrane and water molecules takes place instantaneously and this type of water easily diffuses due to the weak interactions between the water molecules and the membrane polymer. Furthermore, the diffusion processes of the electrolyte solution such as NaAc and Na2SO4 aqueous solutions in the positively charged membrane have also been examined.     

Poly(acrylic acid)-poly(ethylene glycol) layers on positively charged surface coatings: molecular structure, protein resistance, and application to single protein deposition

A new copolymer (PAA-PEG2000) has been designed, consisting of a negatively charged poly(acrylic acid) (PAA) backbone to which poly(ethylene glycol) (PEG) side chains with a molecular weight of about 2 kDa were grafted in a molecular ratio of 3:10. It readily adsorbs to positively charged surfaces and may be considered to be the anionic counterpart of PEG-grafted poly(l-lysine) (PLL-PEG), which was first described by Kenausis et al. and is widely used to render negatively charged surfaces protein-resistant. The synthesis of PAA-PEG2000 can be carried out in aqueous solution at room temperature and does not require any sophisticated techniques such as handling in an inert gas atmosphere. Using ellipsometry and infrared reflection absorption spectroscopy (IRRAS), the film structure has been carefully analyzed for copolymer adsorption onto three different positively charged surfaces, namely, thin layers of poly(allylamine) (PAH), poly(ethyleneimine) (PEI) and (3-aminopropyl)triethoxysilane (APTES). Besides the film thickness, the conformation of the PEG chains and their orientation with respect to the surface normal appear to be important parameters for the protein resistance of the films. Although PAA-PEG2000 adsorbed to PAH and PEI renders the surfaces inert, only partial protein resistance has been observed if the copolymer is deposited on APTES. In a model application, we have generated heterogeneous surfaces composed of isolated small Au nanoparticles (AuNP's) embedded in a protein-resistant layer of PAA-PEG2000 and demonstrated that the AuNP's can serve as adsorption sites for single protein species. In the future, these nanopatterned surfaces may be used for the investigation of isolated proteins.