Complexation and luminescence spectroscopic studies of europium(III) with polymaleic acid

Abstract

Eu / Polycarboxylic acid / Complexation / Laser spectroscopySummary. The complexation behavior of europium(III) with polymaleic acid (PMA) was studied at pH 5 in 0.1 M NaClO 4 by anion exchange (AE). The concentration range investigated was from 10 −9 M to 10 −4 M for the europium ion and from 1 to 50 mg/l for the polymer. The quantitative description of experimental data showed the formation of a 1 : 1 Eu : PMA complex and the existence of at least two distinct interaction environments ("sites") of Eu with the polymer chain whose proportions varied with the ratio between total Eu and PMA concentrations. The existence of different sites was further demonstrated by Time Resolved Laser-induced Fluorescence Spectroscopy (TRLFS) measuring the lifetimes and emission spectra of EuPMA complexes. By using empirical relationships, environments implying 1 : 2 and 1 : 1 Eu : COO − coordination could be deduced. The results show similarities with published data obtained for fulvic and Aldrich humic acids as far as complexation properties at pH = 5 are concerned.

Quantitative description and local structures of trivalent metal ions Eu(III) and Cm(III) complexed with polyacrylic acid

“…7A) considering only one species as observed by Kubota et al [1]. The conditional constant obtained at pH 5 (log K app = 6.65) is comparable with the values given in the literature and determined using the anionic exchange separation method (log K app = 6.23) [2] or the displacement method based on a liquid/liquid separation procedure (log K app = 7.06) [1]. The one deduced from the displacement method using a solid/liquid separation methodology appears therefore underestimated (log K app = 5.24) [3].…”

“…According to the model, to ensure balanced charges within the gel phase, three positive charges need to be compensated by three negative charges. It was experimentally shown that at saturation, the number of bound metal ions corresponds to the number of deprotonated carboxylic groups determined by potentiometric titration [2,7]. This appears coherent with an ion exchange model.…”

“…In the past 10 years, the interaction of trivalent metal ions (lanthanides and actinides) with polyacrylic acid (PAA) was extensively studied [1][2][3][4][5][6][7][8]. Some authors intended to describe the coordination of polymer chain bound metal ions using spectroscopic tools [3][4][5][6][7] while the goal of some other was to quantify the processes [1][2][3] by macroscopic batch titration experiments. The coordination environment of M(III) bound to PAA was notably studied by time-resolved laser fluorescence spectroscopy (TRLFS) with Eu as a fluorescent probe.…”

“…The data could be well described at a given pH value considering the existence of a single complexed species. Depending on the methods used, the conditional complexation constant varies by more than two orders of magnitude [1][2][3]. A change in the Eu coordination was proposed to explain the variation of the conditional complexation constants with pH [1].…”

Comparison of complexed species of Eu in alumina-bound and free polyacrylic acid: A spectroscopic study

“…The degree of PAA loading, corresponding to the ratio between concentrations of sorbed PAA (in mg/L) and of alumina (in g/L), was equal to Γ=59±3 mg/g. This value corresponds to the maximum of adsorption deduced from isotherm data [23]. Under these conditions, the alumina surface is saturated by PAA.…”