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.     

Separation of metals by liquid surfactant membranes containing crown ether carboxylic acids

A water-in-oil-in-water emulsion liquid membrane system is used to transport alkali metal and alkaline earth cations from an external alkaline aqueous source phase through an organic membrane containing a crown ether carboxylic acid and into the internal acidic aqueous phase of the emulsion droplet. The influence of varying the crown ether carboxylic acid structure upon the selectivity and efficiency of competitive metal ion transport is examined.     

Fullerene‐Crown Ether Coated Piezoelectric Crystal Liquid Chromatographic Detector for Metal Ions and Polar/Nonpolar Organic Molecules

Fullerene(C60)‐dibenzo‐16‐crown‐5‐oxyacetic acid (DBI6C5‐OCH₂‐COOC₆₀) was prepared and applied as the coating material on piezoelectric quartz crystals for detection of various metal ions and polar/nonpolar organic molecules. The C60‐crown ether‐coated piezoelectric crystal sensor with a home‐made computer interface for signal acquisition and data processing was applied as an ion chromatographic (IC) detector for various metal ions, e.g., alkali metal, alkaline earth metal and transition‐metal ions. The piezoelectric detector exhibited quite good sensitivity of 10⁴ ～ 10⁶ Hz/M and good detection limit of 10^?3 ～ 10^?4 M for these metal ions. The C60‐crown ether piezoelectric detector compared well with the commercial conductivity detector conventionally used for metal ions. The ionic size and ionic charge seemed to have significant effect on the frequency response of the piezoelectric detector. The C60‐crown ether coated piezoelectric crystal sensor was also employed as a high performance liquid chromatographic (HPLC) detector for various polar organic molecules with frequency responses in the order: amines > carboxylic acids > alcohols > ketones. Furthermore, nonpolar organic molecules, e.g., n‐hexane, 1‐hexene and 1‐hexyne, were also detected with this piezoelectric crystal detector. The frequency responses of the piezoelectric crystal detector for these nonpolar organic molecules were in the following order: alkynes > alkenes > alkanes. The effects of solvents and flow rate on the frequency responses of the piezoelectric crystal detector were investigated. The C60‐crown ether coated piezoelectric crystal detector also showed short response time (< 1 min.) and good reproducibility.     

A New optical liquid membrane study technique : II. A Holographic interferometric study of transport through a liquid membrane

A liquid membrane consisting of a crown ether carboxylic acid dissolved in chloroform placed between a basic source aqueous solution and an acidic receiving aqueous solution was observed in a holographic interferometer to transport potassium ion by coupled counter-ion transport. Steady-state transport was achieved and quite precise measurements of the rate of transport made. The evolution of concentration gradients as a function of time was directly observed.     

Competitive transport of alkali metal ions from aqueous media into toluene solutions of 2-(sym-dibenzo-16-crown-5-oxy)-decanoic acid. A comparative study

Competitive permeation of alkali metal ions from an alkaline source phase into or through a toluene phase facilitated by the lipophilic crown ether carboxylic acid 2-(symdibenzo-16-crown-5-oxy)-decanoic acid is studied in liquid—liquid extraction, bulk liquid membrane transport, and emulsion liquid membrane transport. Most rapid transport was obtained in emulsion liquid membrane experiments. Some differences in selectivity orders for alkali metal permeation were observed for the three separation techniques.     

Preparation and Application of Cholesteryl‐Benzo‐15‐Crown‐5/Cholesteryl Mixed Liquid Crystals

Various mixed liquid crystals containing crown ether‐cholesteryl liquid crystal, benzo‐15‐crown‐5‐COO‐C₂₇H₄₅ (B15C5‐COOCh), with various common cholesteric liquid crystals, e.g., cholesteryl chloride, cholesteryl benzoate and cholesteryl palmitate, were prepared and studied using polarizing microscopy and differential scanning calorimetry. Investigating the concentration effect of B15C5‐COOCh in mixed liquid crystals revealed that the addition of B15C5‐COOCh resulted in wider phase transition temperature ranges of these cholesteryl liquid crystals. The stability of these B15C5‐COOCh/cholesteryl mixed liquid crystals was studied using comprehensive graphic molecular modeling computer programs (Insight II and Discover) to calculate their molecular energy and stability energy. The effect of salts, e.g. Na⁺, Co³⁺, Y³⁺ and La³⁺, on the transition temperature range of the mixed liquid crystals was also investigated. The crown ether cholesteric liquid crystal B15C5‐COOCh was applied both as a surfactant and an ion transport carrier to transport metal ions through liquid membranes. Cholesteryl benzo‐15‐crown‐5 exhibited distinctive characteristics of a surfactant and the critical micellar concentration (CMC) of the surfactant was investigated by the pyrene fluorescence probe method. Cholesteryl benzo‐15‐crown‐5 was successfully applied as a good ion transport carrier (Ionophore) to transport various metal ions, e.g. Li⁺, Na⁺, La³⁺, Fe³⁺ and Co³⁺, through organic liquid membranes. The transport ability of the cholesteryl benzo‐15‐crown‐5 surfactant for these metal ions was in the order: Co³⁺ ≥ Li⁺ > Fe³⁺ > Na⁺ > La³⁺.     

硒功能化杯[4]芳烃对金属离子的识别及在PVC基质支撑液膜的传输作用

提出以PVC为基质的支撑液膜传输体系，研究了以新研制的硒功能化杯[4]芳烃 为活性载体，邻苯二甲酸二辛酯（DOP）为膜溶剂的PVC基质支撑液膜对金属离子的 传输性能。采用双层夹心膜电位法测定了活动载体-金属离子在膜中的配合物生成 常数，对离子在膜中的传输速率、选择性系数以及生成常数之间的相关性作了研究 。使用该体系发现，在8种金属离子中汞具有最快的传输速率；进一步讨论了硒功 能化杯[4]芳烃对金属离子的识别作用和支撑液膜传输机理。     

Piezoelectric Crystal Liquid Flow Detection Systems Based on Alkyl (C18)‐Benzo‐15‐Crown 5 for Organic Compounds and Metal Ions

A water in soluble long‐chain crown ether alkyl (C18)‐benzo‐15‐crown‐5 was synthesized and applied as a coating material on quartz crystal membranes of a liquid flow piezo electric crystal sensor. The oscillating crown ether‐coated piezo electric (PZ) crystal with a home‐made computer inter face was prepared as a liquid chromato graphic (LC) detector for organic species and metal ions in aqueous solutions. The oscillating frequency of the quartz crystal decreased due to the adsorption of organic molecules or metal ions on crown ether molecules. Effects of functional group, molar mass, steric hindrance, and polarity of organic molecules on frequency responses of the crown ether coated PZ crystal detector were investigated. The frequency responses of the crown ether coated PZ crystal detector for various molecules were in the order: amines > carboxylic acids > alcohols > ketones. The crown ether PZ detector also exhibited good sensitivity for some heavy metal ions and the frequency shifts were in the order: Cr³⁺ » Pb²⁺ > Co²⁺ > Cd²⁺ > Ni²⁺ > Cu²⁺. The crown ether coated piezo electric crystal LC detector demonstrated low detection limits for various polar organic molecules, e.g., 6.0 × 10^?5 M for propylamine, and metal ions, e.g., 2.9 × 10^?5 M (1.8 ppm) for Cu²⁺; the crown ether PZ detector also gave good reproducibility when re used. A quite sensitive electrochemical quartz crystal microbalance (EQCM) detection system was also set‐up for detecting trace heavy metal ions in solutions. The variation in frequency of the PZ crystal and the diffusion current were observed simultaneously after the reduction in heavy metal ions such as Cu²⁺ and Ni²⁺. The EQCM detection system exhibited fairly good sensitivity, e.g., 112 Hz/ppm for Cu²⁺ and a good detection limit, e.g., 0.13 ppm for Cu²⁺ ions. Comparison between EQCM and PZ detection systems was made and discussed.     

Interaction between anionic polyelectrolytes and anion exchange membranes and change in membrane properties

Electrodialytic transport properties of anion exchange membranes were measured after formation of anionic polyelectrolyte layers on the membrane surfaces: relative transport number of various anions to chloride ions, current efficiency and apparent diffusion coefficients of neutral molecules. The anionic polyelectrolyte layers were formed by immersing the membrane into an aqueous solution of polycondensation product of sodium naphthalene sulfonate and formaldehyde or polystyrene sulfonic acid.

The change in the relative transport number between anions was remarkable in the anion exchange membrane with high ion exchange capacity by forming the layer. Results were: the relative transport number of sulfate ions to chloride ions decreased and those of nitrate ions to chloride ions, fluoride ions to chloride ions and bromide ions to chloride ions increased compared with the corresponding membrane. Although the apparent diffusion coefficient of neutral molecules suggested clogging of the membrane pores by the polyelectrolyte, anions with higher hydrated ionic diameter were able to permeate through the membrane easily. This means that difference of electrostatic repulsion force against two anions is effective on the change in the relative transport number of anions.     

冠醚配合物的研究 XI: 若干苯并-18-冠-6甲基衍生物液膜传输碱金属离子

本文研究了2,3-苯并-11-甲基-18-冠-6,2,3-苯并-8,15-二甲基-18-冠-6和2,3-苯并-8, 11, 15-三甲基-18-冠-6的氯仿液膜对Na^+, K^+, Rb^+的传输速率。结果指出,传输速率随膜相冠醚浓度增是加而增加, 两者成线性关系; 当冠醚的醚环上甲基数增加则传输速率减小; 对同一冠醚, 不同金属离子的传输速率与相应配合物稳定常数的大小顺序有一致关系; 冠醚传输金属离子时, 阴离子一起迁移, 阴离子水合能力越强则传输能力越小; 传输速率与搅拌速度成线性关系。     

四烷基锡中性载体推动亚硝酸根离子迁移穿透大块液膜

通过大块液膜体系研究了四烷基锡的碳链长度、载体浓度.NO_2~-浓度及抗衡离子等因素对NO_2~_穿透含四烷基锡的液膜的传质速率的影响,讨论了它们与四烷基锡为载体的离子电极性能间的关系。NO_2~-通过四烷基锡为载体的液膜的迁移规律符合离子对传输模式。     

冠醚改性聚甲基硅氧烷液膜离子传输性能

合成了两种新型的冠醚改性聚甲基硅氧烷，研究了它们作为液膜离子传输载体对离子的传输性能，并考察了膜的稳定性。     

Facilitated transport of copper(II) across supported liquid membrane and polymeric plasticized membrane containing 3-phenyl-4-benzoylisoxazol-5-one as carrier

The potential of 3-phenyl-4-benzoylisoxazol-5-one (HPBI) as metal extractant has been evaluated for the first time for Cu(II) transport from aqueous nitrate solutions by supported liquid membrane (SLM) in the solvents chloroform, 2-nitro phenyl octyl ether (NPOE) and dodecyl nitro phenyl ether (DNPE). The efficiency of the membrane transport was optimized as a function of pH, temperature, aqueous phases and membrane composition. It follows the sequence CHCl₃ > DNPE > NPOE. The results suggested that the transport mechanism was mainly controlled by the diffusion of the Cu(PBI)₂ complex in the membrane core. A comparative investigation of Cu(II) transport ions has been made between SLM and polymeric plasticized membrane (PPM), containing HPBI with NPOE and DNPE as organic solvents or plasticizers in order to evaluate the feasibility of PPM with HPBI.     

Applications of Macrocyclic Polyethers in Analytical Sensors and Ion Separation

Artificial macrocyclic polyethers were synthesized and applied as neutral carriers for ion-selective PVC membrane electrodes, ion-chromatographic packing materials, extractants and adsorbents for ion separation, coating materials for piezoeletrical membrane sensors for organic species, and ion-transport carriers through liquid membranes. Ion-selective electrodes such as those for K⁺ Na⁺, UO₂²⁺, Cs⁺, Pb²⁺, Fe³⁺, Hg²⁺ and Ag⁺ ions based on crown ether-phosphotungstic acid (PW) precipitates and dithio crown ethers respectively were prepared and showed good sensitivity and selectivity. Crown ether-PW precipitates were applied as adsorbents of rare-earth ions and some common heavy-metal ions. Some rare-earth ions were easily extracted with crown ethers, especially 15-crown-5. Poly(stytene/divinyl benzene) cryptand-22 resin was synthesized and applied as a bifunctional stationary phase of ion chromatography to separate bom cations and anions, even some organic carboxylate geometric isomers. Crown ethers such as mono-benzo-15-crown-5 was successfully applied as a coating material on piezoelectric quartz membrane sensors for some organic species. The oscillation frequency of the crown-ether quartz-membrane sensor was sensitive to organic vapours such as amines and alcohols. Upon adsorption of organic species on the crown-ether quartz membrane, the oscillation frequency of the sensor decreased obviously. Special crown ether such as dibenzo-16-crown-5-oxyacetic acid, decyl-cryptand-22 and 1, 4-dihydro-pyridine-18-crown-5 were synthesized and successfully applied as ion-transport carriers (ionophores) for transport of Na⁺ K⁺ and Mg²⁺ ions through liquid membranes.     

Transport of ions through the oil phase of W(1)/O/W(2) double emulsions

Using a capillary video microscopy technique, the ion transport at liquid-liquid interfaces and through a surfactant-containing emulsion liquid membrane was visually studied by preparing a double emulsion globule within the confined space of a thin-walled, transparent, cylindrical microtube. NaCl and AgNO(3) were selected as the model reactants and were prepared to form a NaCl/AgNO(3) pair across the oil film. By observing and measuring the formed AgCl deposition, it was found that both Cl(-) and Ag(+) could transport through a thick oil film and Ag(+) was transported faster than Cl(-). Interestingly, the ion transport was significantly retarded when the oil film became extremely thin (<1 microm). The results suggested that the transport of ions mainly depends on the "reverse micelle transport" mechanism, in which reverse micelles with entrapped ions and water molecules can be formed in a thick oil film and their construction will get impeded if the oil film becomes extremely thin, leading to different ion transport rates in these two cases. The direction of ion transport depends on the direction of the osmotic pressure gradient across the oil film and the ion transport is independent of the oil film thickness in the investigated thick range. Ions with smaller Pauling radii are more easily entrapped into the formed reverse micelles and therefore will be transported faster through the oil film than bigger ions. Oil-soluble surfactants facilitate ion transport; however, too much surfactant in the oil film will slow down the ion migration. In addition, this study showed no support for the "molecular diffusion" mechanism of ion transport through oils.     

三正辛胺-二甲苯液膜迁移Cd(Ⅱ)的研究

研究了三正辛胺-二甲苯支撑液膜体系中搅拌速率、反萃剂、三正辛胺浓度、料液中H+浓度等因素对Cd(Ⅱ)离子迁移的影响.用大块液膜测定了不同温度时Cd(Ⅱ)离子跨膜迁移的萃取及反萃取的表观速率常数k₁和k_2.实验表明,温度升高,k₁和k₂均增大(k₁>k₂),且达到膜相最大镉离子浓度时所需的时间逐渐减少.膜相积累的镉离子浓度达最大时,Cd(Ⅱ)离子跨膜传输为稳态传输.根据Arrhenious关系得到膜相萃取反应和反萃取反应的活化能分别为23.8和19.3kJ/mol.     

Highly Efficient and Selective Membrane Transport of Silver(I) Using Dibenzodiaza‐15‐Crown‐4 as a Selective Ion Carrier

A chloroform membrane system containing dibenzodiaza‐15‐crown‐4 was found to be a highly efficient and selective transport of Ag⁺ ions through a chloroform liquid membrane. In the presence of thiosulfate ion as a suitable ion stripping agent in the receiving phase, the amount of silver transported across the liquid membrane after 105 minis 95 ± 1.3%. The selectivity of Ag⁺transport from aqueous solutions containing Tl⁺, Pb²⁺, Cd²⁺, Ni²⁺, Co²⁺, K⁺, Ca²⁺, Sr²⁺, Hg²⁺, Zn²⁺, Cu²⁺was investigated. The interfering effect of Cu²⁺ ions was drastically diminished in the presence of EDTA as a proper masking agent in the source phase.     

Ethylenediamine as a liquid chemical reagent to probe hydrogen bonding and host-guest interactions with crown ethers in an ion trap tandem mass spectrometer

Ethylenediamine (EDA) was used as a novel liquid chemical reagent to probe hydrogen bonding and host-guest interactions with crown ether derivatives in an ion trap mass spectrometer (ITMS). Selective ion/molecule reaction product ions were generated by reactions of EDA with oxygenated and aza-crown ethers. For the oxygenated crown ethers, glycols and dimethylglycols, ion/molecule reactions led to the formation of the protonated molecules ([M+H](+)) and adduct ions including [M+30](+), [M+44](+) and [M+61](+). The aza-crown ethers produced [M+H](+), [M+13](+) and [M+27](+) ions. Collisionally activated dissociation (CAD) experiments were applied to probe the binding strength of these ion/molecule reaction products. CAD results indicated that all these hydrogen-bonding complexes are weakly bound except for the [M+44](+) ion of 18-crown-6, since all the complexes dissociate to the protonated polyether and/or protonated EDA. Fragmentation of the [M+H](+) ions under CAD conditions indicates the extensive covalent bond cleavage of the protonated crown ether skeleton.     

Strategy for Designing New Li+ ion Specific Receptors. A Combination of Theoretical Calculations and Experimental Techniques

Our strategy for designing new receptor molecules specific for Li+ ions is to combine two methods, theoretical calculations and the experimental technique. In developing the Li+ ion-specific receptors, we regarded crown ether derivatives of a 12-membered ring and side arms with functional groups as building blocks. This strategy worked well to synthesize new receptor molecules which selectively bind and transport the Li+ ion.     

Chiral Discrimination of Amino Acids by an Optically Active Crown Ether Studied by HPLC, Extraction and a Liquid Membrane Transport Experiments

A chiral crown ether incorporating a methyl -d-mannopyranoside unit displayed pronounced enantioselection of amino acids in partition liquid chromatography experiments involving solvent systems of limited miscibility: water–ethanol–2,2,4-trimethylpentane. The same system has been used for amino acid transport across a liquid membrane containing the crown ether, and in liquid–liquid extraction experiments. Remarkable enantioselection has been noted for amino acids in all the processes studied.