Ion-exchange high-performance liquid chromatography of nucleotides and polypeptides on new types of ion-exchange sorbents, based on polystyrene-coated silicas.

A novel type of ion exchanger was prepared by multipoint covalent binding of polystyrene chains onto the surface of porous silica followed by polymer-analogous modification of the bonded layer. Both anion and cation exchangers were synthesized and examined in the separation of nucleotides and proteins. Rapid and efficient separation of basic polypeptides on strong anion exchangers and that of acidic polypeptides on strong cation exchangers could be achieved. For the separation of complete mixtures of polypeptides the application of zwitter-ionic ion exchangers can be recommended.     

Fluidization of cation exchangers with regenerating sulfuric acid solution

Dependences of the bed expansion of cation exchangers (weakly acidic Lewatit CNP 80 and strongly acidic KU-2×8) on the flow velocity, temperature, and concentration of the regenerating sulfuric acid solution were determined. An equation describing the dependence of the bed expansion of cation exchangers on the flow velocity, temperature, and concentration of sulfuric acid, common to the two ion exchangers, was derived, which allows a priori determination of the extent of bed expansion in regeneration of cation exchangers in the fluidization mode.     

Ermittlung des Vernetzungsgrades und Beladungszustandes von Ionenaustauschern auf Kunstharzbasis durch Pyrolyse-Gas-Chromatographie

A special introduction device with switching of carrier gas for improving the reproducibility of pyrolysate composition in pyrolysis gas-chromatography has been described. Its influence on the formation of pyrolysis products and on retention times has been studied on a model substance. The peak area ratios for determining the degree of cross-linking in ion exchangers on styrene-DVB basis can be estimated considerably more accurately with the help of carrier gas switching. Since anion exchangers yield lessα-methylstyrene on pyrolysis than do cation exchangers, their peak area ratios are appreciably larger. Increasing the degree of cross-linking lowers the ratios with the anion exchangers and raises them with the cation exchangers. At 400° C the thermal attack on anion exchangers with styrene-DVB matrix occurs mainly at the active group. The methyl esters or their decomposition products formed from the counter ions are characteristic pyrolysis products. A feature of Dowex 1 is the formation of trimethylamine; of Dowex 2, acetaldehyde. In this way, pyrolysis gas-chromatography enables information about the degree of cross linking and the nature of the anion of ion exchangers, as well as about the matrix, type and structure of the functional group and position of substitution of the anchor group in the matrix to be obtained.     

Ionic polymers VI. Chemical stability of strong base anion exchangers in aggressive media

The chemical stability in aggressive media of two types of strong base anion exchangers was studied. The anion exchangers were a commercial Amberlite IRA-400 with a styrene structure and an unconventional resin obtained by the quaternization of a 4-vinylpyridine: 8% divinylbenzene copolymer with methylchloride. The presence of the quaternary nitrogen atoms in or out of the aromatic ring had a great influence on the chemical stability of the ion exchangers.     

A review of the radiation stability of ion exchange materials

A comprehensive literature survey on the radiation stability of ion exchangers resulted in the publication of an extensive data compilation on the effects of ionizing radiation on synthetic organic ion exchangers in this journal (Vol. 97, No. 1). This paper is a brief review of the majorfindings of this literature survey along with similar information on synthetic inorganic ion exchangers. The primary goal of this literature survey is to review present knowledge on the effects of ionizing radiations on synthetic ion exchange materials used in radiochemical processing. Although there are gaps in our knowledge of the mechanisms of radiolytic changes in ion exchangers, the information available in the literature shows some general trends and similarities in observed qualitative effects by different types of organic and inorganic ion exchange materials. These trends and observations have been formulated into a set of qualitative and semi-quantitative statements that can be useful to potential users of ion exchange materials in nuclear material processing and radioactive waste management. Present knowledge, of the behavior of ion exchangers under the influence of ionizing radiations is too limited to justify quantitative predictive modeling.     

Comparison of silica-based and polymer-based cation exchangers for the ion chromatographic separation of transition metals

Silica gel- and polymer-based exchangers differ not only in the substrate but usually also in the structure of their sulphonic acid exchange group. The performance and chromatographic behaviour of modern macroporous poly(styrene-divinylbenzene) polymers of 5-μm particle size after surface sulphonation were examined. Further, two commercially available silica gel cation exchangers were investigated as references for what is now possible and how the chromatographic performance is influenced by the substrate and the structure of the exchange site. The influence of the capacity of surface-sulphonated exchangers for acid and complexing eluents, which are necessary when transition metals are to be separated, was studied. The interaction of polarizable metal cations with the π-system of the polymer depends on the resin capacity, and a comparable dependence for H⁺ and complexing eluents was found. The distance of the functional group from the core influences the adsorption effects dramatically. Lowering the non-specific interaction increases the chromatographic efficiency rapidly. The performance of silica gel-based exchangers is nearly one order of magnitude better than that of surface-sulphonated exchangers. The selectivity of the exchangers investigated is strongly dependent on the structure of the exchange site and on the resin capacity.     

双功能聚合物基质阳离子交换固定相的制备及其在离子色谱中的应用

离子色谱是分离分析阳离子型化合物的重要手段之一。高效阳离子交换固定相的制备研究对离子色谱技术的发展具有重要的意义。该文以丙烯酸和顺丁烯二酸酐为单体,2-巯基乙基磺酸钠为巯基改性剂,提出了聚合物基质微球巯基改性自由基聚合修饰方法,用以制备新型双功能的阳离子交换固定相。该固定相以羧基和磺酸基为功能基,仅用简单的强酸淋洗液便可以实现常规阳离子的基线分离。利用色谱学模型,对金属离子和有机胺的保留行为进行了研究。采用梯度淋洗模式,可在24 min内实现10种阳离子的分离,表明固定相具有优异的色谱性能。“巯基-烯”修饰方法简单、高效。此外,通过调节巯基改性剂的比例能够实现对固定相交换能力的调控。     

Kinetic Regularities of the Kabachnik–Fields Reaction under Catalysis by Sulfonic Cation Exchangers Based on Petroleum Asphaltenes

Kinetics and Catalysis - Strongly acidic cation exchangers were obtained by the sulfonation and successive sulfonation and nitration of petroleum asphaltenes. The cation exchangers were...     

Characteristics of Novel Types of Substituted Cerium Phosphates

The disodium, dilithium, dipotassium and distrontium forms of cerium phosphate were prepared from their corresponding mono-forms. The chemical content of these inorganic ion exchangers have been characterized by inductively coupled plasma (ICP) spectroscopy. The ion exchange properties of these cation exchangers, their chemical stability and selectivity for certain ions were investigated. It was found that, by introducing different salts into the reaction mixture used to prepare cerium phosphate, robust cation exchange materials of reproducible composition with a good cation capacity, and suitable for column use, are produced. All the ion exchangers with the exception of CeP (dipotassium) show excellent selectivity towards certain cations, thereby increasing the potential practical applications of these inorganic exchangers.     

New nitrogen-and-phosphorus-containing fibrous ion exchangers for water treatment

New nitrogen-and-phosphorus-containing fibrous ion exchangers were produced by two-stage synthesis from Nitron fiber. The ion exchangers are efficient sorbents of heavy and nonferrous metals from aqueous solutions under dynamic conditions.     

New phosphorus-containing sorbents based on wheat straw and glycidyl methacrylate for Hg<Superscript>2+</Superscript> removal

The possibility of preparing new phosphoric acid cation exchangers based on wheat straw and glycidyl methacrylate was explored. The mercury(II) ion sorption properties of the prepared cation exchangers were studied.     

Acid-Base Properties and Structural Features of Composite Ion Exchangers Based on KU-23 and KM-2p Cation Exchangers and Hydrated Zirconium Oxide

A method for introduction of hydrated zirconium oxide into macroporous cation exchangers KU-23 and KM-2p and the acid-base properties and structural features of the composite ion exchangers are described.     

Enthalpies of sorption of glycine from aqueous solutions by carboxylic cation exchangers

The influence of glycine acidity on its interactions with carboxylic cation exchangers in the protonated and deprotonated forms was investigated by the calorimetric and sorption methods. The enthalpies of sorption of glycine on KB-2 and KB-4 cation exchangers at various pH were determined.     

Distribution and catalytic activity of sulfonic acid groups in organic ion exchangers

The existence of inhomogeneities in the polymer structure of ion exchangers was demonstrated and their influence on catalytic properties was shown. The results are based on the differences in catalytic activity of two ion exchangers with low degrees of sulfonation differing in the distribution of active groups within the polymer particles.     

Sorption of chromium(VI) on ion-exchange resins and sorbents

Sorption of Cr(VI) on AV-17 and EDE-10P anion exchangers, KU-2 and KB-4 cation exchangers, activated charcoal, and foamed graphite (STRG) is studied.     

Synthesis and Physicochemical Study of Polyfunctional Ion Exchangers Based on Dextramine Waste from Levomycetin Production

New polyfunctional anion exchangers are synthesized from dextramine (waste from levomycetin production) by condensation of its glycidyl ethers with certain polyamines. The polycondensation conditions are optimized, and physicochemical properties of the resulting ion exchangers are studied.     

ELECTRIC REGENERATION METHOD OF IONEXCHANGE RESIN IN THE MIXED BED

1.INTRODUCTIONThemixedbedofionexchangeisanecessnywatertreatmentunitfortheProduchonofpurewaterandsuperpurewaterinelectricindustryandthermalpowerplant.Ingeneral,inthemixedbed,theionexchangeresinsconsistofthestronglyacidicionexchangeresininfree-acidformandstronglybasicionexchangeresininfree-baseform.TheexhaustedresinswillberegeneratedbyusingthestrongacidandstrongalkalirespechvelyThiskindofregenerationmethodwithacidandalkalihasfollowingdefectsf1.TheutilizationefficiencyofregenerantSisvarylow…     

Composite sorbents of inorganic ion-exchangers and polyacrylonitrile binding matrix

Methods of preparation of granules of inorganic ion exchangers as well as methods for improvement of granular strength of these materials are reviewed. The resulting ion exchangers are classified in three groups—“intrinsic”, supported and composite ion exchangers. Their properties are compared and possibilities of their technological application are evaluated. A new method of preparation of inorganic-organic composite sorbents of inorganic ion-exchangers and polyacrylonitrile binding matrix is described, advantages and disadvantages of such sorbents are discussed. Proposed fields of application include tratment of liquid radioactive and/or hazardous wastes, decontamination of natural water as well as analytical applications.     

Ion exchange extraction of platinum(IV) and palladium(II) from hydrochloric acid solutions

Sorption concentration of platinum(II, IV) and palladium(II) from freshly prepared and aged two-yearold hydrochloric acid solutions by a series of anion exchangers with different functional groups and of different physical structure of Purolite and CYBBER grades was studied. The high sorption ability of the ion exchangers in relation to the extracted chlorocomplexes of noble metals is shown. It was demonstrated that palladium(II) from all tested ion exchangers can be completely desorbed with thiourea solutions acidified with hydrochloric acid, while complete desorption of platinum is achieved only from Purolite S 985 anion exchanger of the complexforming type and Purolite A 111 weak base anion exchanger.     

The equilibrium sorption of sulfuric acid by weakly basic polyacrylic anion exchangers synthesized on the basis of polyamines

The equilibrium ion-exchange sorption of sulfuric acid by the free base form of weakly basic polyacrylic anion exchangers with the gel (Relite MG1) and porous (Relite MG1/P) structures was studied. It was proved that the bisulfate variety of the anion exchangers did not form. Solutions of resinates were found to be nonideal. Their nonideality was analyzed in terms of the theory of exchange equilibria to suggest a model of the exchange of doubly-charged anions on fixed polyamine exchange centers of Relite MG1 and Relite MG1/P anion exchangers. The type of the ion was found to have no effect on sorption parameters.