Assessing the uranium DGT-available fraction in model solutions

Jiujiang Zhao; R J Cornett; C L Chakrabarti

doi:10.1016/j.jhazmat.2019.121134

Assessing the uranium DGT-available fraction in model solutions

J Hazard Mater. 2020 Feb 15:384:121134. doi: 10.1016/j.jhazmat.2019.121134. Epub 2019 Sep 5.

Authors

Jiujiang Zhao¹, R J Cornett², C L Chakrabarti³

Affiliations

¹ Key Laboratory of Eco-Geochemistry, Ministry of Natural Resources, National Research Center for Geoanalysis, 26 Baiwanzhuang Street, Beijing, 100037, China; Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, K1S 5B6, Canada. Electronic address: zhaojiujiang@cags.ac.ca.
² Department of Earth and Environmental Sciences, University of Ottawa, ON K1N 6N5, Canada.
³ Department of Chemistry, Carleton University, 1125 Colonel By Drive, Ottawa, Ontario, K1S 5B6, Canada.

PMID: 31732352
DOI: 10.1016/j.jhazmat.2019.121134

Abstract

The uranium speciation in humic acid (HA) and fulvic acid (FA) model solutions was investigated by diffusive gradients in thin films (DGT). A reference solution was used to normalize the DGT data from different samples. This approach was used to assess uranium DGT-available fraction (F_U), which was calculated from experimental data and reflect both the mobility and lability of uranium species. F_U decreased with increasing HA or FA concentrations, because more uranium was able to bind the strong binding sites of HA or FA. When copper was spiked, F_U increased due to the competition between copper and uranium. In HA model solutions, an increase of ionic strength could increase F_U, and when pH was greater than 7, F_U increased significantly. The DGT uptake factor (φ), which can be obtained from data fitting, is the ratio of the product of diffusion coefficient and lability degree of the unknown sample to that of the reference solution. In U-HA-NaHCO₃ solutions, UO₂(CO₃)₂^2- had a relatively high φ value and might be the most DGT-available species. This approach allows the comparison of DGT data from different samples, and combining with a data fitting procedure, it can be used to investigate the distribution of metal species.

Keywords: Diffusive gradients in thin films (DGT); Fulvic acid; Humic acid; Metal speciation; Uranium.

Publication types

Research Support, Non-U.S. Gov't