The histone lysine monomethyltransferase SETD8 is an epigenetic regulator of cell cycle progression. Nahuoic acid A (1), a polyketide produced in culture by a Streptomyces sp. obtained from a tropical marine sediment, is the first known selective SAM-competitive inhibitor of SETD8. The structure of nahuoic acid A (1) has been elucidated by chemical transformation and detailed analysis of spectroscopic data.

A series of linear polyamine functionalised weak base anion exchange resins have been synthesised using the Merrifield resin and characterised using infra-red spectroscopy, thermogravimetry, elemental analysis and solid state 13 C nuclear magnetic resonance spectroscopy. Uptake behaviour towards uranium (as uranyl) from sulfuric acid media has been assessed as a function of pH and sulfate concentration, with comparison to a commercially available weak base anion exchange resin, Purolite S985. Synthetic polyamine resins were seen to outperform the commercial resin at industrially relevant uranyl concentrations, with a trend of increased uptake being seen with increasing polyamine chain length. Uranium loading isotherm studies have been performed and fit with the Langmuir and Dubinin-Radushkevich isotherm models, with a maximum loading capacity observed being 269.50 mg g-1 for the longest polyamine chain studied. Extended X-ray absorption fine structure experiments have been used to determine uranium coordination environment on the resin surface, showing a [UO2(SO4)3] 4species. This coordination knowledge was employed to develop an extraction mechanism and derive an isotherm model based on the law of mass action.

This is a repository copy of Insights on uranium uptake mechanisms by ion exchange resins with chelating functionalities: Chelation vs. anion exchange.

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Three in-house produced polyamine functionalised ion exchange resins and Purolite S985 (a commercial ion exchange resin) have been assessed for their ability to extract UO2 2+ from a variety of aqueous matrices applicable to current and potential future uranium mining processes. The uptake of common contaminant species in uranium processing liquors at variable acid concentrations has been assessed, with Al 3+ and MoO4 2showing the most extraction, with AsO4 3-, Eu 3+ and Fe 3+ showing extractions > 10% at low [H + ]. Extraction of MoO4 2-, AsO4 3-, Eu 3+ and Fe 3+ was seen to decrease with increasing [H + ]. The impact of increasing [Cl-] on UO2 2+ and Fe 3+ extraction has been determined. Fe 3+ showed low extractions by all resins, with no dependence on [Cl-]. In contrast, increasing suppression of UO2 2+ uptake was seen with increasing [Cl-] up to 80 g L-1 , with extraction remaining constant beyond this [Cl-]. At high [Cl-] (> 50 g L-1) Purolite S985 was seen to remove UO2 2+ from solution more effectively than all synthesised polyamine resins. The presence of Fe 3+ in solution was seen to suppress UO2 2+ uptake by around 10% when [Fe] 3+ /[UO2] 2+ increased from 0 to 2. Fe 3+ extraction by all studied resins was promoted by the presence of UO2 2+ in solution. This was most prevalent with Purolite S985, with an extraction of 30% for [Fe] 3+ /[UO2] 2+ = 2 by Purolite S985. All resins were tested using a process water from a uranium mine and have shown an ability to selectively extract UO2 2+ from such solutions, with the best synthetic resin recovering 15.7% more uranium than Purolite S985.

Uptake behaviour of uranium from aqueous, acidic sulfate and chloride media on iminodiacetic acid chelating resin Purolite S930+ has been studied. Experiments have followed UO2 2+ , Cu 2+ and Fe 3+ uptake behaviour with respect to acidic and ionic media type and concentration. Uptake suppression of all metals was observed at [H + ] > 0.1 M sourced from H2SO4 and HCl. In contrast, significant uptake of Fe 3+ was observed from solutions with [HCl] > 2 M. Suppression of UO2 2+ uptake (up to 15%) was observed upon increasing [SO4 2-] to 4 M, whilst negligible UO2 2+ uptake suppression was observed with [Cl-] up to 6 M. The impact of Fe 3+ concentration on UO2 2+ extraction under hypersaline conditions ([Cl-] = 22.6 g L-1 , 0.64 M) has been studied and behaviour fit to Langmuir and Dubinin-Radushkevich isotherms. Extended X-ray absorption fine structure (EXAFS) studies have been performed to assess the effect of salinity on the uranium coordination environment on the resin and therefore the mechanism of uptake. No change in surface species was observed, with the fit species being uranyl bound by the iminodiacetic acid functional group in a tridentate motif, with an associated bidentate sulfate group. An isotherm model based on this surface has also been derived. It has been shown that at pH 2 there is little impact of increasing chloride and sulfate concentrations on the extraction behaviour of metals onto Purolite S930+ under the conditions tested. Rather, uranium uptake is more affected by the presence of Fe 3+ in solution. As [Fe 3+ ]/[UO2 2+ ] is increased from 0 to 2, UO2 2+ uptake is reduced by up to 66% at aqueous equilibrium.