Electrochemical behavior of fission palladium in 1-butyl-3-methylimidazolium chloride

Nowadays much attention is being paid to the determination of trace amounts of noble metals in geological, industrial, biological and environmental samples. The most promising techniques, such as inductively coupled plasma atomic emission spectrometry (ICP-AES), inductively coupled plasma mass spectrometry (ICP-MS) and electrothermal atomic absorption spectrometry (ETAAS) are characterized by high sensitivity. However, the accurate determination of trace noble metals has been limited by numerous interferences generated from the presence of matrix elements. To decrease, or eliminate, these interferences, the sorption preconcentration of noble metals is often used prior to their instrumental detection. A great number of hyphenated methods of noble metal determination using sorption preconcentration have been developed. This review describes the basic types of available sorbents, preconcentration procedures and preparations of the sorbent to the subsequent determination of noble metals. The specific features of instrumental techniques and examples of ETAAS, FAAS, ICP-AES, ICP-MS determinations after the sorption preconcentration of noble metals are considered. The references cited here were selected mostly from the period 1996 - 2006.

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Trends in Sorption Preconcentration Combined with Noble Metal Determination

Extraction of palladium (II) from nitric acid medium by imidazolium nitrate immobilized resin

Combined methods for the determination of noble metals with the use of sorption preconcentration with complexing, anion-exchange, and other sorbents are reviewed. Characteristics of sorbents, techniques of sorption preconcentration, and techniques for the preparation of a concentrate for determination are considered. Features of instrumental methods for the determination of noble metals in the analysis of different materials are discussed. Examples of the use of sorption preconcentration in combined methods for the determination of noble metals are given from publications between 1996–2005.

Sorption Preconcentration in Combined Methods for the Determination of Noble Metals

Calcium phosphate with hydroxyapatite structure was synthesized and its ability to adsorb Cr(VI) from aqueous solution is presented. XRD, BET, IR, TGA, SEM and EDS techniques were used to characterize the obtained material. A pure phase was obtained through a simple synthesis process. The specific surface area of the synthesized powder was found to be 64.5 m 2 g -1 . The X-ray diffraction pattern shows that the calcium phosphate formed was nanocrystalline with an average grain size of approximately 75 nm. A fast adsorption was observed and in less than 24 h it was found that 2.41 x 10 -4 meq g -1 of Cr(VI) ions were adsorbed on calcium phosphate. Desorption experiments showed that Cr(VI) adsorption decreased to 2.23 x 10 -4 meq g -1 of calcium phosphate. This behavior is a consequence of partial dehydration of the synthesized material. Calcium phosphate can be effectively used for removing Cr(VI) from aqueous solutions in treatment processes of metal wastes.

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Síntesis y caracterización de fosfato de calcio y su relación con las propiedades de adsorción del Cr(VI)

Separation of palladium by strongly basic anion exchangers IRA-110 and IRA-900 from intermediate radioactive liquid waste in chloroacetic acid/nitrate medium containing thirteen elements have been achieved. Different conditions have been studied, the effect of NaNO3 as salt content, chloroacetic acid and hydrogen ion concentration have been investigated. Selective recovery of palladium from the [ILLW] solution was achieved using the column technique. The selectivity increased by using chloroacetic acid/nitrate than in nitrate medium. The elution of palladium was carried out via reduction with formic acid where the rate of the reduction process was increased by decreasing the formic acid concentration till 50% followed by dissolving the separated palladium by nitric acid.

Separation of palladium from simulated intermediate radioactive waste/chloroacetic acid/nitrate medium by IRA-410 and IRA-900 anion exchangers

Zirconium phosphate hase been prepared by solid-solid reaction. The characterization of this inorganic ion exchanger was done with respect to capacity, pH titration, dissolution, etc. The preconcentration and separation of fission products, Sr(II), Co(II), Eu(III), Gd(III), Hg(II) and Am(III) has been achieved from different acidic media, HCl, HNO3, H2SO4, HClO4. The speciation of these cations in different media has been investigated. From the results obtained, it is obvious that these cations can be preconcentrated in low acidic medium, whilst at high acidity in the range 1-2 M, they be can separated from each other.

E. El-Sherif

Papers

Separation of palladium from simulated intermediate radioactive waste/chloroacetic acid/nitrate medium by IRA-410 and IRA-900 anion exchangers

Separation and speciation of fission products by zirconium phosphate prepared by solid-solid reaction