Extraction of noble metals and rare earth elements using plants

Noble metals (NMs) and rare earth elements (REEs) are becoming increasingly crucial in modern industry, particularly in green high-tech applications. As demand for these valuable metals continues to surge, their natural reserves are being depleted. Therefore, recovery of high-value metals from secondary minerals is essential for sustainable development. Phytomining has emerged as a sustainable approach for recovering NMs and REEs from alternative resources, offering a promising and sustainable solution for the production of these valuable metals. This study provides a glimpse of the overall phytoextraction-enrichment-extraction concept, with a particular focus on the final stage of extraction to reclaim NMs and REEs from bio-ores. Although phytomining has been effectively implemented for Ni across various scales, its application to NMs and REEs remains in its early stages. Within the phytoextraction-enrichment-extraction chain, the extraction phase plays a critical role in reclaiming these valuable elements. However, research on extracting NMs and REEs from biomass residues is currently scarce. This gap of knowledge likely arises from the novelty of the field, presenting both significant challenges and promising opportunities for further study. Moreover, existing extraction techniques have largely relied on pyrometallurgical and hydrometallurgical methods, both of which pose environmental concerns and entail high operational costs. Therefore, it is essential to investigate and advance eco-friendly, innovative techniques, with a particular focus on bio-metallurgy, to efficiently recover NMs and REEs from biomass ashes.