mPAM/mCMC双极膜电解槽中MnO2电催化氧化制备甘油醛

分别以FeCl3和戊二醛等对羧甲基纤维素(CMC)和聚丙烯酰胺(PAM)进行改性, 制备了mPAM/mCMC双极膜. 测定了PAM、CMC胶体的电荷密度, mPAM/mCMC双极膜离子交换能力、I-V工作曲线等参数. 用扫描电镜和红外光谱对膜形貌与成分作表征, 膜厚≈260 μm, 中间界面层厚为纳米级. 热重分析表明膜具有较好的热稳定性. 以mPAM/mCMC双极膜为电解槽的隔膜, 间接电氧化甘油为甘油醛. 在电场的作用下, 双极膜中间层中的水离解产生H＋和OH−, OH−及时地传输入阳极室, 中和了电生成甘油醛时生成的H＋, 促进了正向反应的进行. 槽电压稳定, 产率达91.6%, 电流效率为65.5%.     

一种具有识别运输钠离子的离子通道膜的制备

以三氯甲烷为溶剂,用3-异氰酸基丙基三乙氧基硅烷和对氨基苯酚合成得到一种自组装杂化材料——3-(脲基酚基)丙基三乙氧基硅烷.采用FTIR、XPRD分析方法对该化合物的结构以及晶体形态进行了表征.利用旋涂法和共混法分别制备离子通道膜,采用ATR-FTIR和SEM分析手段表征膜的化学结构和形态结构,并通过自制的膜运输实验装置测定膜的传输性能并提出了相应的传输机理.实验结果表明,两种方式所得的离子通道膜表面是致密无孔的,致密层厚度为8～10μm左右;采用共混法制得的离子通道膜的传输速度较旋涂法快.离子通道是杂化材料通过分子自组装形成的,该通道可以识别并运输Na+.     

Revealing the kinetics of ionophore facilitating ion transport across lipid bilayers by surface enhanced infrared absorption spectroscopy

Ionophore can prominently improve the ion permeability of cell membrane and disrupt cellular ion homeostasis.Most studies regarding ionophore facilitating ion transmembrane transport focus on artificial liquid-liquid interfaces,which have large difference from the actual environment of cell membrane.Here,we construct a supported lipid bilayeron a gold nanoparticles film modified ZnSe prism as an appropriate model of cell membrane to investigate the dynamic of the ion transport facilitated by ionophore using surface enhanced infrared absorption spectroscopy(SEIRAS).We find that the ion transmembrane transport consists of two steps:The ion transmembrane transport starts with the association/disassociation between ion and ionophore at the edge of lipid bilayer;The second step is the transfer of ion-ionophore complex across lipid bilayer.Our results show that the complex transfer across the lipid bilayer is the rate determining step.     

Controlling the transport of cations through permselective mesoporous alumina layers by manipulation of electric field and ionic strength

The electric field-driven transport of ions through supported mesoporous gamma-alumina membranes was investigated. The influence of ion concentration, ion valency, pH, ionic strength, and electrolyte composition on transport behavior was determined. The permselectivity of the membrane was found to be highly dependent on the ionic strength. When the ionic strength was sufficiently low for electrical double-layer overlap to occur inside the pores, the membrane was found to be cation-permselective and the transport rate of cations could be tuned by variation of the potential difference over the membrane. The cation permselectivity is thought to be due to the adsorption of anions onto the pore walls, causing a net negative immobile surface charge density, and consequently, a positively charged mobile double layer. The transport mechanism of cations was interpreted in terms of a combination of Fick diffusion and ion migration. By variation of the potential difference over the membrane the transport of double-charged cations, Cu2+, could be controlled accurately, effectively resulting in on/off tunable transport. In the absence of double-layer overlap at high ionic strength, the membrane was found to be nonselective.     

Selective transport of Ag(Ⅰ) ion across a bulk liquid and polymer membranes incorporated with di-N-benzylated O_3N_2 donor macrocycles

<正>The selective bulk liquid membrane and polymer membrane transports of Ag(Ⅰ) from an aqueous solution containing seven metal cations,Co(Ⅱ),Ni(Ⅱ),Cu(Ⅱ),Zn(Ⅱ),Ag(Ⅰ),Cd(Ⅱ) and Pb(Ⅱ),was studied.The source phases contained equimolar concentrations of the above-mentioned cations,with the source and receiving phases being buffered at pH 5.0 and 3.0,respectively. Ag(Ⅰ) ion transport occurred with a good efficiency from the aqueous source phases across the bulk liquid membrane and polymer membrane(derived from cellulose triacetate) containing ligand 1 as the ionophores,into the aqueous receiving phases.Clear transport selectivity for Ag(Ⅰ) was observed using ligand 1.There was no selectivity for the cations using ligand 2 in the both bulk liquid membrane and polymer membrane transports.     

Ionic behavior modification of cation exchange ED membranes by using CMC-co-Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles for heavy metals removal from water

A new mixed matrix polyvinyl chloride-based heterogeneous cation exchange membrane was prepared by incorporation of carboxy methyl cellulose-co-Fe₃O₄ nanoparticles through solution casting technique. The effect of simultaneous using of carboxy methyl cellulose and iron oxide nanoparticles in the casting solution on the physicochemical properties of membranes was studied. SOM images showed uniform particles distribution and uniform surfaces for the membranes relatively. The SEM images exhibited regular direction/spatial orientation for the CMC-co-Fe₃O₄ nanoparticles in the membrane matrix. XRD patterns showed that membrane heterogeneity was enhanced by using of Fe₃O₄ nanoparticles. Membrane ion exchange capacity, membrane surface hydrophilicity, membrane potential, surface charge density, transport number, selectivity, and ionic flux were increased by using CMC/Fe₃O₄ nanoparticles in membrane matrix. Results showed that membrane areal electrical resistance was declined up to 3.8 Ω cm² by utilizing CMC/Fe₃O₄ nanoparticles in the casting solution. Also PVC/CMC-co-Fe₃O₄ membrane showed higher transport number, selectivity, flux, and electrical conductivity compared to PVC/CMC membrane and unmodified ones. Electrodialysis experiment in laboratory scale showed higher dialytic rate in lead ions removal for PVC/CMC-co-Fe₃O₄ nanoparticle-mixed matrix ion exchange membrane compared to PVC/CMC membrane and pristine one.     

Selective transport of cesium ion in polymeric CTA membrane containing calixcrown ethers

A series of calixcrown ethers for which the cavity size of the crown ring is varied from crown-6 to crown-7 to crown-8 were examined for the transport abilities toward alkali metal ions. These ligands were incorporated into supported liquid membranes (SLMs) and into polymer inclusion membranes (PIMs) composed of cellulose triacetate (CTA) as a support and 2-nitrophenyl octyl ether (NPOE) and tris(2-butoxyethyl) phosphate (TBEP) as a plasticizer. In both membrane systems, calixcrown-6 showed the best selectivity toward a cesium ion over other alkali metal ions. The polymeric CTA membrane showed more rapid transport rate as well as higher durability than did the SLMs.     

Selective Transport of Copper(II) Ion across a Polymer Membrane Incorporating a Difunctional Schiff-base Ionophore

The selective polymer membrane transport of Cu(II) from an aqueous solution containing seven metal cations, Co(II), Ni(II), Cu(II), Zn(II), Ag(II), Cd(II) and Pb(II), was studied .The source phase contained equimolar concentrations of the above-mentioned cations, with the source and receiving phases being buffered at pH 4.9 and 3.0, respectively. Cu(II) ion transport occurred (J=2.82 × 10⁻⁷ mol/h at 25 °C) from the aqueous source phase across the polymer membrane (derived from cellulose triacetate) containing ligand (I) as the ionophore, into the aqueous receiving phase. Clear transport selectivity for Cu(II) was observed.     

Synthesis of DnaK and GroEL in Escherichia coli cells exposed to different magnetic field signals

The effects of extremely low frequency magnetic field (ELF-MF)(1 mT, 50 Hz) on the heat shock protein (HSP) synthesis in Escherichia coli were investigated. Two magnetic field signals were studied: sinusoidal (SMF) and pulsed square wave (PMF). It was found that bacteria exposed to SMF showed a significantly higher level of DnaK and GroEL proteins as compared to sham-exposed bacteria as revealed by Western blot, whereas a lower level was observed after PMF exposure. Similar results were obtained when bacterial cells were exposed to heat shock (HS) after ELF-MF exposure: again SMF and PMF resulted in an increase and in a reduction of HSP amount in comparison with sham control, respectively. In conclusion, the MF influences the synthesis of HSPs in E. coli in a way that critically depends on the signal characteristics.     

Influence of a cellulose diacetate matrix on the complexation kinetics of tetraphenylporphin with Zn and Cd

The dependence of the reaction rate of tetraphenylporphin zinc and cadmium complexes in a polymer matrix on a base of cellulose diacetate and low-molecular model solutions was investigated. The characteristics of the diffusive transport of aqueous solutions of zinc and cadmium acetates through the cellulose diacetate membrane were obtained. The kinetic control of the porphyrin reaction incorporated into the polymer, and the determining influence of the steric limitations of the matrix of a rigid chain polymer on macroheterocycle deformation (and thus its reactivity) are shown.