Abstract
Abstract: In the present study, the feasibility to use phosphate solubilizing bacteria (PSB) to develop a biological leaching process of rare earth elements (REE) from monazite-bearing ore was determined. To predict the REE leaching capacity of bacteria, the phosphate solubilizing abilities of 10 species of PSB were determined by halo zone formation on Reyes minimal agar media supplemented with bromo cresol green together with a phosphate solubilization test in Reyes minimal liquid media as the screening studies. Calcium phosphate was used as a model mineral phosphate. Among the test PSB strains, Pseudomonas fluorescens , P. putida , P. rhizosphaerae , Mesorhizobium ciceri , Bacillus megaterium , and Acetobacter aceti formed halo zones, with the zone of A. aceti being the widest. In the phosphate solubilization test in liquid media, Azospirillum lipoferum , P. rhizosphaerae , B. megaterium , and A. aceti caused the leaching of 6.4%, 6.9%, 7.5%, and 32.5% of calcium, respectively. When PSB were used to leach REE from monazite-bearing ore, ~5.7 mg/L of cerium (0.13% of leaching efficiency) and ~2.8 mg/L of lanthanum (0.11%) were leached by
Highlights
Rare earth elements (REE) have been increasingly used in the fields of optics, permanent magnetism, electronics, superconductor technology, hydrogen storage, medicine, nuclear technology, secondary battery technology, and catalysis [1,2,3]
Another study on REE leaching from phosphate minerals apatite and monazite by organic acids such as citric, oxalic, phthalic, and salicylic was published, even though chemical organic acids were used in this study, which were not biologically produced [9]
The elemental composition of the raw monazite-bearing ore used in this study is shown in Table 1, which was measured by alkali fusion with Na2CO3 for silica, permanganametric titration for calcium, and ICP after multi-acid digestion for the other elements [21]
Summary
Rare earth elements (REE) have been increasingly used in the fields of optics, permanent magnetism, electronics, superconductor technology, hydrogen storage, medicine, nuclear technology, secondary battery technology, and catalysis [1,2,3]. The authors used Aspergillus ficuum, organic acid producing fungi, and Pseudomonas aeruginosa, organic acid/siderophore producing bacteria They found that those microorganisms produced citric, oxalic, or 2-ketogluconic acid and dissolved 55% and 47% of REE from monazite by A. ficuum and P. aerunoginosa, respectively. Another study on REE leaching from phosphate minerals apatite and monazite by organic acids such as citric, oxalic, phthalic, and salicylic was published, even though chemical organic acids were used in this study, which were not biologically produced [9]. In a soil improvement process, phosphate solubilizing bacteria (PSB) have been widely used because they affect the release of phosphorous (P) from inorganic and organic P pools through solubilization and mineralization [13,14,15] by organic acid production. The REE leaching abilities of the PSB from monazite-bearing ore were determined and compared with the screening data
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
