Biosorption of Rare-Earth Elements from Aqueous Solutions and Their Mineralization by Microscopic Fungi

Abstract Biosorption is a promising method for preventing rare-earth element (REE) migration in natural environments and for their purification, and microscopic fungi are considered effective biosorbents. This article is devoted to studying the biosorption capacity of soil microscopic fungi in relation to REEs in aqueous solutions. The dynamics of adsorption is studied using the example of lanthanum by the biomass of micromycetes Penicillium canescens and Talaromyces funiculosus, depending on the contact time and its concentration in the solution. It is found that adsorption equilibrium in the fungal biomass–aqueous lanthanum solution system occurs within 24 h; the T. funiculosus biomass demonstrates a higher sorption capacity. Lanthanum adsorption is more intense at medium acidic pH values of solutions; the maximum lanthanum sorption for 24 h is noted at pH 3.1 by P. canescens biomass. It is revealed that REEs with larger ionic radii are extracted more effectively; they more actively occupy free sorption centers with the formation of complexes. With the prolonged interaction between REEs and fungal biomass, nanoparticles are formed, the composition of which is similar to monazite. According to IR spectroscopy data, the REE sorption centers are amide, carboxyl, amine, and phosphate groups of the fungal cell wall. The presence of many ionogenic groups determines the high sorption capacity of the fungal cell wall. Intermolecular modeling of the interaction of lanthanum with amino acid residues of fungal cell wall proteins reveal that proteins form strong complexes by the complex formation of REE with amino acid residues, where the active centers are glutamic and aspartic amino acids.