Selective Removal of ²²⁶Ra²⁺ from Gas-Field-Produced Waters

Abstract

The 226Ra2+ selectivity of both the self-assembled (iso)-guanosine-based systems and ionizable thiacalix[4]crown dicarboxylic acids was determined in gas-field-produced water and a metal ion-containing model solution (simulant). Seven gas-field-produced water samples have been analyzed. From a sample (K5D) with average metal ion concentrations ([metal(tot)] = 0.14 M), thiacalix[4]crown-5 dicarboxylic acid (10(-4) M) extracts 60% of the 226Ra2+ content. Extractions performed with the model solution ((M)K5D) indicate that in K5D there is significant competition in 226Ra2+ extraction due to the organic constituents of K5D, in particular with self-assembled extractants guanosine and isoguanosine. Nevertheless, all four extractants extract 226Ra2+ both from the produced water K5D and the model solution (M)K5D, even with a 100-fold excess of [metal(tot)] to [extractant]. The extracted 226Ra2+ cations could effectively be stripped from the extractants bywashing with pH 2 water. The results obtained with the extractants used, especially thiacalix[4]crown-5 dicarboxylic acid 3, clearly demonstrate the way to selectively remove Ra2+ from gas-field-produced waters.

Towards the stable chelation of radium for biomedical applications with an 18-membered macrocyclic ligand

“…29 A further body of work in this eld has been directed towards the development of organicsoluble extractants that partition this ion to the organic phase in biphasic systems. [29][30][31][32][33][34][35][36][37][38] Of these extractants, the most common structural motif explored has been that containing a calixarene core. Although calixarene-based ligands have demonstrated efficiency for the selective extraction of Ra 2+ in the context of environmental remediation, [32][33][34][35] attempts to use these ligands for Ra 2+ complexation for nuclear medicine applications have been unsuccessful due to either failed radiolabeling 36 or poor kinetic stability of the resulting complex.…”

“…[29][30][31][32][33][34][35][36][37][38] Of these extractants, the most common structural motif explored has been that containing a calixarene core. Although calixarene-based ligands have demonstrated efficiency for the selective extraction of Ra 2+ in the context of environmental remediation, [32][33][34][35] attempts to use these ligands for Ra 2+ complexation for nuclear medicine applications have been unsuccessful due to either failed radiolabeling 36 or poor kinetic stability of the resulting complex. 29 These unsuccessful efforts have led many in the radiopharmaceutical community to the conclusion that stable chelation of 223 Ra sufficient for its in vivo use cannot be achieved.…”

Synthesis and complexation study of (1,4-linked)-homothiaisocalixnaphthalenes

“…We previously reported that the [1 + 1] coupling between the corresponding bis(mercaptomethyl)-8 and bis(bromomethyl)-naphthalenes 9, respectively, in basic and high dilution conditions produced tetrahomodithiacalix [4]naphthalenes 10 and 11 12,13 in reasonable yields (Scheme 2). These new homodithiacalix [4]naphthalenes were used as precursors for the syntheses of the corresponding homocalix [4]naphthalenes via extrusion of the sulfur atoms, 11 and although these compounds were found to be able to complex with Ag + their complexation properties were not investigated in any detail at that time.…”

“…Ag + , Zn 2+ , Cd 2+ , Hg 2+ ), alkali or alkaline earth metal ions, 3 and as has recently been shown, for the selective removal of 226 Ra from gas-field-produced waters. 4 Thiacalix [4]arene itself has been prepared using either a one-step procedure, 5 from para-tert-butylphenol and sulfur, or more efficiently via the sulfur-bridged dimer 2, 6 or by a less efficient multi-step process via the linear tetramer 3 7 (Scheme 1).…”

The development of isoguanosine: from discovery, synthesis, and modification to supramolecular structures and potential applications

“…In addition, a signicant radium ion ( 226 Ra 2+ ) preference over other monovalent alkali cations was observed for both 57 and 53, with a "precipitation prevention/ dissolving" property over a wide pH range. And, in 2005, Reinhoudt 193 et al reported that Ra 2+ can be selectively extracted from gas-eld produced water by isoG-based self-assemblies.…”