Evaluation and application of Diffusive Gradients in Thin Films (DGT) technique using Chelex®-100, Metsorb™ and Diphonix® binding phases in uranium mining environments

Abstract

A new resin- Diphonix(®) in Diffusive Gradients in Thin Films (DGT) technique for the determination of uranium was investigated and compared with previously used binding phases for uranium, Chelex(®)-100 and Metsorb™. The DGT gel preparation and the elution procedure were optimized for the new resin. The U uptake on Diphonix(®) resin gel was 97.4 ± 1.5% (batch method; [U] = 20 μg L(-1); 0.01 M NaNO3; pH = 7.0 ± 0.2). The optimal eluent was found to be 1 M 1-hydroxyethane-1, 1-diphosphonic acid (HEDPA) with an elution efficiency of 80 ± 4.2%. Laboratory DGT study on U accumulation using a DGT samplers with Diphonix(®) resin showed a very good performance across a wide range of pH (3-9) and ionic strength (0.001-0.7 M NaNO3). Diffusion coefficients of uranium at different pH were determined using both, a diffusion cell and the DGT time-series, demonstrating the necessity of the implementation of the effective diffusion coefficients into U-DGT calculations. Diphonix(®) resin gel exhibits greater U capacity than Chelex(®)-100 and Metsorb™ binding phase gels (a Diphonix(®) gel disc is not saturated, even with loading of 10.5 μmol U). Possible interferences with Ca(2+) (up to 1.33 × 10(-2) M), PO4(3-) (up to 1.72 × 10(-4) M), SO4(2-) (up to 4.44 × 10(-3) M) and HCO3(-) (up to 8.20 × 10(-3) M) on U-DGT uptake ([U] = 20 μg L(-1)) were investigated. No effect or minor effect of Ca(2+), PO4(3-), SO4(2-), and HCO3(-) on the quantitative measurement of U by Diphonix(®)-DGT was observed. The results of this study demonstrated the DGT technique with Diphonix(®) resin is a reliable and robust method for the measurement of labile uranium species under laboratory conditions.

A combined DGT - DET approach for an in situ investigation of uranium resupply from large soil profiles in a wetland impacted by former mining activities

“…For Dgel(U), a mean value derived from Gregusova and Docekal (2011) associated with a larger uncertainty accounting for discrepancies in the literature values has been chosen (Dgel = 4.39 ± 0.40 × 10 -6 cm² s -1 at 25°C and pH = 6.4). This value is in good agreement with those reported in several studies Turner et al 2012, Drozdzak et al 2015, 2016. The quantitative determination by ICP-MS requires a reproducible elution of metals trapped in the Chelex ® resin.…”

“…For ion analysis, high SO4 2-, Mg 2+ and Ca 2+ contents were observed in pore water from non-organic soil layers and a high concentration of Fwas noted in L4. Under these working conditions, no parameter appears to exert a major influence on the diffusion coefficients used in DGT calculations (Drozdzak et al 2015, Turner et al 2012).…”

Labile trace metal concentration measurements in marine environments: From coastal to open ocean areas

“…c T,M is the total dissolved metal concentration (Co from Dulaquais et al (2017) and the other metals from Ebling and Landing (2015) for the Mediterranean Sea and our data for the BCZ. Percentages of each pool (free, inorganic and organic) are from Stockdale et al (2011;2015;2016). in stands for inorganic and org for organic.…”

Diffusive gradients in thin films: devices, materials and applications

“…The DGT technique was developed in 1994 by William Davison and Hao Zhang with use for the determination of trace metals in water most common, during the early stages of development (Davison and Zhang 1994;Zhang and Davison 1995). Since then, the DGT technique has been modified and expanded to allow measurement of a significant number of elements and compounds, including multiple metals (Altier et al 2016;Gao et al 2009;Gimpel et al 2003;Yabuki et al 2014), nutrients (Cai et al 2017;Menzies et al 2005), organic chemicals/compounds (Chen et al 2012a(Chen et al , 2013Dong et al 2014), radioactive elements (Drozdzak et al 2015;Leermakers et al 2009), oxyanions (Stockdale et al 2008(Stockdale et al , 2010 and rare earth elements (Yuan et al 2018). The simultaneous measurement of metals and oxyanions via DGT also provides an opportunity for analysis of the complex relationships between various elements (Mason et al 2005;Panther et al 2013;Wang et al 2017a).…”