Extraction of some strategic elements from thorium–uranium concentrate using bioproducts of Aspergillus ficuum and Pseudomonas aeruginosa

Abstract

The activity of the bioproducts from Aspergillus ficuum and Pseudomonas aeruginosa for extraction of thorium (Th4+), uranium (UO22+) and rare earth elements (REEs) from thorium–uranium concentrate was studied. P. aeruginosa produce element-specific ligand (siderophore) that is able to change pH and enhance chelation of Th4+ and UO22+. The produced siderophore at pH 5.3 has the ability to bioleach and is complexed with 68.00% of uranium and 65.00% of thorium. Also, A. ficuum produced different kinds of organic acids which leached 30.00% of uranium and 29.12% of thorium in addition to 20.00% of lanthanum, 33.00% of cerium and 2.51% of yttrium as rare earth elements at pH 3.0. Oxalic acid was efficient for Th4+, UO22+and REEs precipitation. The binocular stereo-microscope (BSM), environmental scanning electron microscope (ESEM) and X-ray diffraction (XRD) analyses confirmed the percentages of extracted metals. Exogenous polysaccharides (EPSs) seem to play an important role in bioleaching and removal of these elements. It was found that EPSs produced by A. ficuum adsorbed Th4+, UO22+ and REEs while that produced by P. aeruginosa adsorbed REEs only.

Keywords

• Extraction
• Thorium
• Uranium
• Rare earth elements
• Aspergillus ficuum
• Pseudomonas aeruginosa
• Bioproducts