Adsorption of radium and barium on goethite and ferrihydrite: A kinetic and surface complexation modelling study

Abstract

Radium and barium uptake onto ferrihydrite and goethite have been studied in the concentration range 1 nM to 5 mM and from pH 4 -10, to develop a model to predict radium behaviour in legacy uranium mining wastes. For ferrihydrite, uptake of Ra 2+ at nM concentrations was strong at pH > 7. At higher concentrations, Ba 2+ sorption to ferrihydrite was slightly weaker than that of Ra 2+ . Experiments with goethite showed weaker binding for both metal ions in all systems. The interactions of radium with both ferrihydrite and goethite are fully reversible. The behaviour of radium during transformation of ferrihydrite to goethite has been studied, and no evidence for irreversible incorporation within the goethite lattice was found; radium uptake to goethite was the same, whether or not it was present during its formation. Calcium competed with radium for ferrihydrite sorption only at high calcium concentrations (>10 mM). Barium is a more effective competitor, and a concentration of 1 mM reduced radium sorption. Sediment samples from a legacy uranium mining site have been analysed, and the in situ R d values are consistent with radium uptake by surface coatings of ferrihydrite or goethite like phases. Surface complexation models have been developed for radium sorption to ferrihydrite and goethite which simulate the experimental data successfully. In both cases, approaches based on a single surface functional group and tetradentate binding sites simulated the data successfully. These data could be used in underpinning the safety case for legacy mining sites.

Study of223Ra uptake mechanism on hydroxyapatite and titanium dioxide nanoparticles as a function of pH

“…The published data on radium sorption using chosen nanoparticles are quite limited and available papers are focused mainly on 226 Ra behavior in uranium mill tailings and the articles studied only iron compounds as a goethite or ferrihydrite, or environmental minerals. [25][26][27] The 223 Ra is a radionuclide used for TAT as radium chloride (Xogo®). 12,[28][29][30] Due to the cascade of emitted alpha particles, it could provide accurate high-dose irradiation of the target tissue (range of the alpha particles approx.…”

A novel solid-state fractionation of naphthenic acid fraction components from oil sands process-affected water

“…By contrast AC has reduced surface functionality, as shown by a recent study of these materials (Kwon and Wilson, 2010). The second discriminating feature is the textural properties where AC has a greater BET surface area ($10 3 m 2 /g) compared to the other materials which all are approximately 10 1 m 2 /g (Bismarck et al, 2002;Ayad and Zaghlol, 2012;Sajih et al, 2014;Han et al, 2015). Fig.…”

Partitioning of naturally-occurring radionuclides (NORM) in Marcellus Shale produced fluids influenced by chemical matrix

“…31,32 We attribute the low observed adsorption of Pb and Ra to the akaganeite and amorphous iron oxides to matrix effects (competition with exchange cations), similarly as observed for ferrihydrite and goethite. 16 …”