Chelating ion exchangers

New chelating ion-exchange resins are able to selectively remove many heavy metals in the presence of high concentrations of univalent and divalent cations such as sodium and calcium. The heavy metals are held as weaMy acidic chelating complexes. The order of selectivity is Cu > Ni > Zn > Co > Cd > Fe + > Mn > Ca. This process is suitable for end-of-pipe polishing and for metal concentration and recovery. 

CONCENTRATION OF COPPER(II) IONS FROM A BRINE SOLUTION USING A CHELATING ION EXCHANGE RESIN... 

E Blasius and B Brozio, Chelating ion-exchange resins. In Chelates in Analytical Chemistry, H A Flaschka and A J Barnard (Eds), Vol. 1, Marcel Dekker, New York, 1967, p 49... 

Chelating ion-exchange resins. E. Blasius and B. Brozio, Chelates Anal. Chem., 1967, 1, 49-79 (149). 

Horwitz EP, Chiarizia R, Dietz ML, Diamond H, Nelson DM (1993a) Separation and preconcentration of actinides from acidic media by extraction chromatography. Anal Chim Acta 281 361-372 Horwitz EP, Chiarizia, R., Diamond H, Gatrone RC, Alexandratos SD, Trochimzuk AQ, Crick DW (1993b) Uptake of metal ions by a new chelating ion exchange resin. 1. Acid dependencies of actinide ions. Solvent Extr Ion Exch 11 943-966... 

Lloyd-Jones, P.J., Rangel-Mendez, J.R., and Streat, M., Mercury sorption from aqueous solution by chelating ion exchange resins, activated carbon and a biosorbent, Process Safety and Environmental Protection, 82 (4), 301-311, 2004. 

A variety of preconcentration procedures has been used, including solvent extraction of metal chelates, coprecipitation, chelating ion exchange, adsorption onto other solids such as silica-bonded organic complexing agents, and liquid-liquid extraction. 

Szczepaniak, W. and Siepak, J., Chelating ion exchanger of the organo-phos-phorus complexone type, Chem.-Anal. (Warsaw), 18, 1019, 1973. 

Figure S.ll shows the flow diagram of the microprocessor-controlled preconcentration equipment, which is configured here for off-line operation, and consists of a sample changer, three separate peristaltic pumps (PI, P2 and P3) for the sample solution, buffer and add, three magnetic valves (VI, V2 and V3), the preconcentration column filled with chelating ion-exchange material (7 mm i.d., 10—30 mm height) and a fractionating unit for the addic column eluate. The flow-rates for the sample solution, buffer and add are adjusted to S ml/min.

Figure 4.14 — (A) Flow injection system for the preconcentration and determination of copper P peristaltic pumps A 0.5 M HNOj B sample q = 2.5 mL/min) C water (jq = 0.5 mL/min) E 1 M NaNOj/O.l M NaAcO, pH 5.4 q = 0.5 mL/min F 1 M NaAcO/2 x 10 M Cu pH 5.0 (9 = 1.0 mL/min) 3-5 valves ISE copper ion-selective electrode W waste I and II 2 and 3 mL of chelating ion exchanger for purification III 100 fil of chelating ion exchanger for metal ion preconcentration. (B) Scheme of the flow system for the determination of halides A 4 M HAcO/1 M NaCl/0.57 ppm F B 1 M NaOH/0.5 M NaCl C, mixing coil (1 m x 0.5 mm ID PTFE tube) Cj stainless-steel tube (5 cm x 0.5 mm ID) ISE ion-selective electrode R recorder. (Reproduced from [128] and [129] with permission of Elsevier Science Publishers and the Royal Society of Chemistry, respectively).

According to the developer, HISORB ion exchange material is less expensive than the more common chelating ion exchange resins (D161780, p. 356 D17038H, p. 2195). 

Chelex 100 and Qrelex 220 Chelating Ion exchange Resin Instmchon Manual, http // www.biorad.com/webmaster/pdfs/9184 Chelex.PDF) (accessed 26 May 2012). 

The more selective kind of ion exchange, the chelating ion exchange [22], suffers often from kinetic limitations, which limit the application range to cationic compounds with fast ligand exchange kinetic for the inner coordination sphere. Ion exchange is well suitable for preconcentration as well as for separation of chemically similar compounds. 

Schwartz, A., Marinsky J. A., and Spiegler, K. S. (1964). Self-exchange measurements in a chelating ion-exchange resin. J. Phys. Chem. 68, 918. 

Depending on the position of metal with respect to the main chain, PCMU can be subdivided into two distinct classes. Polymeric chelates whose main chain contains a metal and which breaks upon its removal are termed coordination polymers. They have been exhaustively described elsewhere [7]. The second class of PCMU which is discussed in this review contains metal in a side chain. In this case the metal can be fairly readily removed or displaced by other metals so that the main chain remains intact. Such PCMU actually incorporate complexes of metals with chelating ion-exchange resins [8]. 

R. M. Cespon Romero, M. C. Yebra-Biurrun, M. P. Bermejo-Barrera, Preconcentration and speciation of chromium by the determination of total chromium(III) in natural waters by flame atomic absorption spectrometry with a chelating ion-exchange flow injection system, Anal. Chim. Acta, 327 (1996), 37-45. 

The FAAS procedure described above, is suitable for the majority of food-analysis applications. In some instances, however, low manganese contents will dictate the use of SEFAAS or EAAS techniques [202—205]. An interesting multielement (Cd, Cu, Co, Mn, Ni, Pb and Zn) scheme using chelating ion exchange has been outlined by Baetz and Kenner [206]. 

Chelate ion exchangers are based on the selective complex formation between a metal ion and a chelating ligand anchored onto the resin s polymeric structure. 

Yoshida, I., Ueno, K. and Kobayashi, H., Selective separation of arsenic (III) and (V) ions with ferric complex of chelating ion-exchange resin, Sep. Sci. 13, 173-184 (1978). 

An attractive approach to the removal of interferents involves the use of the chelating ion-exchange resin Chelex 100. With the exception of iron(Il) and iron(III), all identified cationic interferents can be overcome by passing the sample solution (at pH 4.0) through a column of this resin. The ubiquitous nature of iron, however, precludes the application of this procedure in most practical circumstances. 

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