Analytica Chimica Acta 402 (1999) 91–97 Phosphonate-based resins for the selective enrichment of uranium(VI) Melek Merdivan a , Michael R. Buchmeiser b,∗ , Günther Bonn b a Balikesir University, Science and Arts Faculty, Chemistry Department, Balikesir 10100, Turkey b Institute of Analytical Chemistry and Radiochemistry, University of Innsbruck, A-6020 Innsbruck, Austria Received 5 October 1998; received in revised form 19 June 1999; accepted 25 July 1999 Abstract Phosphonate-derivatized polystyrene–divinylbenzene-based (PS–DVB) resins have been prepared from chloromethylpoly- styrene–divinylbenzene (Cl–CH 2 –PS–DVB) by the Arbuzov-reaction using lithium or sodium alkyl chlorophosphites. Base- promoted hydrolysis of the diethyl phosphite-derivatized resin in refluxing 1,4-dioxane resulted in phosphonic acid-derivatized PS–DVB resins with an average capacity of 0.8–2.2 mmol phosphonate, depending on the alkyl chlorophosphate used. Both the free phosphonic acid as well as the diethyl, dibutyl- and bis(2-ethylhexyl)-phosphonate-derivatized sorbents were investigated in terms of their extraction characteristics for U(VI), Th(VI) as well as for other transition metal ions such as Fe(III), Zn(II), Co(II), Cd(II), Ni(II) and Cu(II) from acidic aqueous solutions. In contrast to phosphonate resins, the phosphonic acid-derivatized resins exhibited a high sorption capacity and selectivity for U(VI). Breakthrough experiments were conducted for both U(VI) and Th(IV) within a pH-range of 0–4. U(VI)-uptake was measured as a function of the concentration of nitric and hydrochloric acids, respectively. The sorbent was found to possess a high selectivity for U(VI) with an optimum extraction pH of 4. Recoveries for U(VI) determined prior to breakthrough were found to be quantitative (97–99%) on the free phosphonic acid resin within the investigated pH-range. Finally, masking and synergetic effects on the extraction efficiency of the phosphonic acid-derivatized resin for U(VI) have been investigated using 5-sulfosalicylic acid as a masking reagent and dipyridyl amine as an auxiliary ligand. ©1999 Elsevier Science B.V. All rights reserved. Keywords: Phosphonate resins; Uranium; Thorium solid-phase extraction (SPE) 1. Introduction Uranium is a prominent element whose isotopes occur in various concentrations and oxidation states in radioactive waste, U(VI) being the most prominent one. Besides this element, many other radioactive as well as inactive nuclides occur in these matri- ces, which basically impede a quantitative analysis ∗ Corresponding author. Tel.: +43-(0)512-507-5184; fax: +43-(0)512-507-2677 E-mail address: michael.r.buchmeiser@uibk.ac.at (M.R. Buchmeiser) of U(VI). Especially digests of nuclear power plant fuel rods show high concentrations of Fe(III) and Ni(II). As a logical consequence, the elimination of all interfering nuclides, or the more attractive route, a quantitative and highly selective removal of U(VI) are, therefore, desirable. So far, this ele- ment has been selectively extracted by liquid–liquid extraction, e.g. using quaternary ammonium salts [1,2], thenoyltrifluoroacetone in xylene [3] or a mix- ture of -diketones and crown ethers [4]. Despite the high selectivity and effectiveness of these lig- ands, some principal disadvantages of liquid–liquid 0003-2670/99/$ – see front matter ©1999 Elsevier Science B.V. All rights reserved. PII:S0003-2670(99)00556-5