Na型蛭石中2Na+=Pb2+离子交换过程的动力学研究

通过实验探讨了Na型蛭石在不同的Pb2 溶液浓度和不同的温度下的2Na =Pb2 离子交换动力学关系,实验结果表明:蛭石中2Na =Pb2 离子交换很快,0.5min以内交换吸附率已达70%～80%以上,达到交换平衡的时间与溶液的起始浓度和交换时的温度有关,原液浓度越大达到平衡所需要的时间越长,温度越高交换越快;蛭石中2Na =Pb2 离子交换过程受粒内扩散控制;动力学方程符合克-金-布扩散(粒内扩散)方程;计算出了蛭石中2Na =Pb2 离子交换过程的表观活化能E'a的平均值为25.21kJ/mol;推导出了蛭石中2Na =Pb2 离子交换过程的动力学方程为:1-2/3α-(1-α)2/3=k0r-20exp-(25.21/R)·1/Tt     

离子交换对硼硅玻璃光学性能的影响

利用电子探针、分光光度计和干涉显微镜等手段,研究了离子交换对硼硅玻璃光学性能的影响。结果表明,离子交换后硼硅玻璃的K+含量沿玻璃厚度方向逐渐降低。当交换时间≤8h时,交换层厚度与交换时间呈线性增加;当交换时间8h时,交换层厚度增加缓慢。离子交换增强后,硼硅玻璃的透过率小幅度下降,但仍保持在91%以上。离子交换后硼硅玻璃中折射率从玻璃表面向内部呈指数降低,这与K+离子在玻璃中的不均匀分布相关。综合考虑应用器件对强度和光学均匀性要求,硼硅玻璃的离子交换时间应不大于3h。     

用离子交换树脂制备纯水（Ⅴ）

用离子交换树脂制备纯水（Ⅴ）南京表面处理研究会（２１００２９）储荣邦，蒋华苗，储春娟１２离子交换树脂的化学性能在这里所说的化学性能，是指树脂与溶液中离子的交换性能。交换性能的优劣与其酸碱性的强弱、离解能力的大小等有关。１２．１交换基团在离子交换树脂大...     

离子交换纤维对Cr(Ⅵ)的交换性能研究

研究了苯乙烯系聚丙烯基阴离子交换纤维对Cr(Ⅵ)的交换性能,考察了酸度、温度和流速等因素对交换性能的影响。实验结果表明,在pH值为3时交换性能最好。离子交换纤维对Cr(Ⅵ)的交换以液膜扩散为主,交换速度很快,8min即可达到交换饱和,交换反应速率常数为0．015s^-1,离子交换过程服从Freundlish等温式。测定了纤维静态饱和交换量为257．6mg／g。温度和流速影响动态交换性能,使得穿透曲线和穿透时间发生改变。与离子交换树脂相比具有交换速度快、交换量大的优点,是一种交换性能优良的分离材料。     

不同离子交换体对碳钢在有机涂层下腐蚀行为的影响

为探讨在离子选择性涂层中离子交换体的不同对金属腐蚀行为的影响,用动电位扫描极化曲线和电化学交流阻抗技术研究了A3钢表面涂装含不同离子交换体的阴离子选择性和阳离子选择性有机涂层在3％NaCl溶液中的腐蚀和电化学行为。实验结果表明,同一种涂层中不同离子交换体对碳钢的腐蚀行为有不同影响,可以通过选择具有缓蚀作用的交换离子来改善涂层的防蚀性能。在阴离子选择性涂层中交换离子为MoO4^2-型时对碳钢的防蚀性能比交换离子为SO4^2-型好,在阳离子选择性涂层中则交换离子为Na^ 型时比交换离子为NH4^ 型好。     

多晶β″-Al_2O_3的稀土离子交换——Ⅰ.显微结构分析

进行了多晶钠β″-Al_2O_3与 Eu~(2+)、Ce~(3+)的离子交换,通过扫描电镜观察和电子探针分析研究了交换过程中的显微结构特征。结果表明,多晶样品的离子交换速度与其晶粒取向和内部缺陷有密切关系。讨论了交换后样品内出现非均匀性和微裂纹的原因。     

质子交换膜中的离子传递

采用分光光度法研究了几种有色离子在质子交换膜内的离子交换，并考虑离子交换膜中两种对离子的伴生扩散，给出了这几种离子的扩散系数。同时，讨论了几种因素对离子交换传递的影响。     

Ni-Fe普鲁士蓝的离子交换选择性研究

研究了Ni—Fe普鲁士蓝对不同价态金属离子的交换选择性。在Ni—Fe普鲁士蓝与一价Cs^＋溶液反应中，Ni—Fe普鲁士蓝主要由K^＋与Cs^＋进行离子交换；而在与二价和三价的离子溶液反应中，离子交换主要是通过目标离子（Cr^3＋、Sr^2＋、Cu^2＋）与K^＋和Ni^2＋发生交换。结合全谱等离子直接光谱（ICP）和穆...     

钒电池用离子交换膜的研究与开发

钒电池(VRB)是一种新型的高效储能电池.离子交换膜是VRB的核心部件之一.总结了VRB用离子交换膜在商业化膜(Nafion、PE-01、JAM等)改性处理及PVA、PVDF、PTFE基阳离子交换膜和ETFE、PPESK基阴离子交换膜研发等方面近4年来的技术进展,指出需重点关注高性能、低成本膜的开发,尤其是新型阴离子交换膜的研究与开发.     

热处理对全氟离子交换膜性能的影响

全氟离子交换膜(PFIEM)是质子交换燃料电池和离子膜氯碱工业的关键材料,在燃料电池、氯碱行业、钒电池等方面应用广泛,是目前无可替代的关键部件之一。它的结构与性能直接关系着电池或电解槽的性能好坏。热处理作为一种传统工艺过程,简便易行,广泛用于全氟离子交换膜性能的研究。从离子膜的不同性能出发,分别阐述了热处理对质子电导率、甲醇透过率、力学性能、选择渗透性等性能的影响,并总结了目前这方面研究的特点与发展方向。     

A new hybrid ion exchanger: Effect of system parameters on the adsorption of vanadium (V)

The hybrid ion exchanger consisted of PONF-g-GMA anion fibrous exchanger and IRA-96 bead-type anion exchanger was developed by combining different types of layers with hot-melt adhesive. Its ion exchange capacity and the pressure drop with flow rate of water were measured and the adsorption of vanadium (V) ions on the hybrid ion exchanger was evaluated with various process parameters such as pH, initial concentration, and temperature. It was observed that the adsorption kinetics of vanadium (V) ions on the hybrid ion exchanger could be analyzed with pseudo-second-order model.     

A comparative study of ion exchange kinetics in zinc/lead-modified zeolite-clinoptilolite systems

The kinetics of zinc and lead ions removal by modified zeolite-clinoptilolite has been investigated. The rate of the ion exchange process for lead ions is faster than for zinc ions, as well as the time needed to reach the equilibrium. The ion exchange capacity of zeolite of lead ions is doubly higher than that of zinc ions. Diffusion models according to the Vermeulen's approximation, the parabolic diffusion model and the homogeneous diffusion model have been tested with the experimental data of ion exchange for zinc and lead. For both systems examined, the best fit of the models proposed with the experimental data was shown by the Vermeulen's approximation and the homogeneous diffusion model with t-->t(infinity). The diffusion coefficients are calculated from kinetic models of lead ions they are of the order of 10(-6)cm(2)/min, constant for all examined initial concentrations and not dependent on time. The diffusion coefficients in the system of zinc ions is of the order of 10(-8)cm(2)/min, also independent of initial concentrations, but decreasing with time from the beginning of ion exchange to the equilibrium.     

Stresses in ion-exchange layers of soda-lime-silicate glass

This paper presents a new method to determine both the magnitude and the sign of the surface stresses that develop as a consequence of sodium/hydrogen ion exchange in soda‐lime‐silicate glass immersed in water. At 90 °C, very thin layers that develop at the surfaces of polished glass specimens are found to have extremely high compressive stresses, ?2.4 GPa. The negative sign of the stress is consistent with earlier findings that the ion‐exchange process involves hydronium ions (H₃O⁺) and not bare protons (H⁺).     

Formation of stable nanolayers of meixnerite via a combined delamination-ion exchange process

A combination of delamination and ion exchange allowed us to obtain new solids consisting of nanolayers of double hydroxides containing hydroxyl as charge balancing ion (i.e., meixnerite monolayers). The solids were prepared from Mg/Al HLCs containing dodecylbenzenesulphonate (DBS) anion in the interlayer region, using a procedure involving sonication and swelling of the interlayer region in the presence of 1-butanol as solvent. This treatment converts the initial, milky dispersion, into a translucent dispersion suggesting that the solid is completely exfoliated. Then, the translucent dispersion is treated with an NaOH solution in 1-butanol in order to exchange DBS- ions with OH- ions and simultaneously precipitate the DBS sodium salt while offsetting charge deficiencies in the solid layers. The exchange process results in no relamination of the structure, which allows a new material consisting of individual nanolayers of meixnerite to be prepared.     

Cathodes Coating Layer with Li-Ion Diffusion Selectivity Employing Interactive Network of Metal-Organic Polyhedras for Li-Ion Batteries (Small 5/2023)

Surface modification of cathodes using Ni-rich coating layers prevents bulk and surface degradation for the stable operation of Li–ion batteries at high voltages. However, insulating and dense inorganic coating layers often impede charge transfer and ion diffusion kinetics. In this study, the fabrication of dual functional coating materials using metal–organic polyhedra (MOP) with 3D networks within microporous units of Li–ion batteries for surface stabilization and facile ion diffusion is proposed. Zr-based MOP is modified by introducing acyl groups as a chemical linkage (MOPAC), and MOPAC layers are homogenously coated by simple spray coating on the cathode. The coating allow the smooth transport of electrons and ions. MOPAC effectively suppress side reactions between the cathode and electrolyte and protect active materials against aggressive fluoride ions by forming a Li–ion selective passivation film. The MOPAC-coated Ni-rich layered cathode exhibited better cycle retention and enhanced kinetic properties than pristine and MOP-coated cathodes. Reduction of undesirable gas evolution on the cathode by MOPAC is also verified. Microporous MOPAC coating can simultaneously stabilize both the bulk and surface of the Ni-rich layered cathode and maintain good electrochemical reaction kinetics for high-performance Li–ion batteries.     

Stable films of cationic surfactants and phthalocyaninetetrasulfonate catalysts.

Films made from cationic surfactants and well-retained redox catalysts were investigated. Full loading of metal phthalocyaninetetrasulfonates (MPcTS4-) into water-insoluble dialkyldimethylammonium surfactants by ion exchange from aqueous solutions yielded coatings on electrodes that retain these catalyst ions for 1-2 weeks in electrolyte solutions. In contrast, partly loaded films lost most MPcTS4- ions in a few hours. All films showed gel-to-liquid crystal phase transitions at temperatures characteristic of surfactant bilayers. Cross-sectional views by SEM showed layers of 0.1-0.2 micron, as well as some disordered regions. Each larger layer is probably made up of stacks of many molecular bilayers. Retention of MPcTS4- ions seems related to their dimerization. Dimers of MPcTS4- associated with ammonium head groups may crosslink adjacent surfactant bilayers. The MPcTS4- ions that enhance stability in these films are also good redox catalysts.     

Cs+-Na+离子交换波导的折射率分布分析

用热扩散法和电场辅助扩散法制备了Ｃａ＾＋－Ｎａ＾＋离子交换玻璃玻导。温度低于玻璃转变温度时，这些波导具有良好的热稳定性。     

Classical retention mechanism in ion exchange chromatography. Theory and experiment

The classical model for ion exchange chromatography is characterized by firmly adsorbed driving ions at the surface of the stationary phase in an amount required by electroneutrality and stoichiometric ion exchange between the bulk of the eluent electrolyte and this immobilized Stern layer. Retention equations have been derived for system peaks, labeled eluent ions, and analytes in a system containing only strong electrolytes by strictly respecting this model. It is shown that the classical model described dependence of retention data on concentration and composition of the binary eluent with excellent precision, but the resulting system parameters were not self-consistent. Inconsistency of the results might be due to contributions from another retention mechanism.     

Quaternized trimethylaminated polystyrene-coated zirconia as a strong anion exchange material for HPLC

The synthesis and characterization of a new, base-stable, strong anion exchange phase by amination of polystyrene-coated zirconia (PS-ZrO2) are described. Even though the ion exchange capacity of the quaternized trimethylaminated PSZrO2 (QTMA-PS-ZrO2) is only 0.07 mequiv/g, it is able to separate various inorganic anions, benzoic acid derivatives, and nucleotides in their deprotonated states. The effects of ionic strength, eluent pH, and counterion type are discussed. In the presence of both phosphate and fluoride ions in the eluent, band broadening caused by Lewis acid/base interactions between zirconia and analytes is greatly suppressed. The mixed retention modes (ion exchange, hydrophobic interaction, and Lewis acid/base interactions) on QTMA-PS-ZrO2 offer a different selectivity toward various anionic analytes than do other zirconia- and nonzirconia-based ion exchangers.     

Chemical control of reaction time in an enzyme assay and feasibility of enzyme spot tests

There are many circumstances in which the understanding of a patient's status would be improved by knowing one or more enzyme activities. Such data are routinely produced in clinical laboratories, but simple, noninstrumental tests for enzymes are a rarity, so their extralaboratory determination is also rare. The essential problem is that effective clinical determinations of enzyme activities are typically carried out by measuring reaction rates, so the reaction time needs to be controlled. The reaction time of a sample can be controlled by using a passive, ion exchange-based titration. In this work, OH-, H+, and quinidine have been used to stop the enzymes LDH (EC 1.1.1.27) (with H+ and OH-) and cholinesterase (EC 3.1.1.8) (with quinidine). The ion exchange material containing the enzyme-stopping ion is separated from the sample by a filter. The sample contains ions that can exchange with the enzyme-stopping ion in the ion exchange material, and it may contain species that buffer the enzyme-stopping ion. The reaction time is governed by the exchanging ion's concentration in the sample, the quantity of buffer in the sample, the thickness of the filter between the ion exchange material and the sample, and the temperature. A test for LDH requiring 50 microL of serum and no instrumentation can be made so that results from sera with elevated levels appear different than those with normal levels.