Department of Chemistry, University of Aveiro, Aveiro, Portugal.
LAQV-REQUIMTE - Associated Laboratory for Green Chemistry, University of Aveiro, Aveiro, Portugal.
Environ Sci Pollut Res Int. 2023 Jun;30(30):74521-74543. doi: 10.1007/s11356-023-27767-8. Epub 2023 May 25.
Efficient and sustainable secondary sourcing of Rare-Earth Elements (REE) is essential to counter supply bottlenecks and the impacts associated with primary mining. Recycled electronic waste (E-waste) is considered a promising REE source and hydrometallurgical methods followed by chemical separation techniques (usually solvent extraction) have been successfully applied to these wastes with high REE yields. However, the generation of acidic and organic waste streams is considered unsustainable and has led to the search for "greener" approaches. Sorption-based technologies using biomass such as bacteria, fungi and algae have been developed to sustainably recover REE from e-waste. Algae sorbents in particular have experienced growing research interest in recent years. Despite its high potential, sorption efficiency is strongly influenced by sorbent-specific parameters such as biomass type and state (fresh/dried, pre-treatment, functionalization) as well as solution parameters such as pH, REE concentration, and matrix complexity (ionic strength and competing ions). This review highlights differences in experimental conditions among published algal-based REE sorption studies and their impact on sorption efficiency. Since research into algal sorbents for REE recovery from real wastes is still in its infancy, aspects such as the economic viability of a realistic application are still unexplored. However, it has been proposed to integrate REE recovery into an algal biorefinery concept to increase the economics of the process (by providing a range of additional products), but also in the prospect of achieving carbon neutrality (as large-scale algae cultivation can act as a CO sink).
高效且可持续地从二次资源中回收稀土元素 (REE) 对于缓解供应瓶颈和减少与初级开采相关的影响至关重要。回收电子废物 (E-waste) 被认为是一种很有前途的 REE 来源，并且已经成功地应用了湿法冶金方法和化学分离技术（通常是溶剂萃取）来从这些富含 REE 的废物中进行回收。然而，产生酸性和有机废水被认为是不可持续的，因此人们一直在寻找“更环保”的方法。基于生物质（如细菌、真菌和藻类）的吸附技术已被开发出来，以从电子废物中可持续地回收 REE。近年来，藻类吸附剂受到了越来越多的关注。尽管其潜力巨大，但吸附效率受到多种因素的强烈影响，如生物质的类型和状态（新鲜/干燥、预处理、功能化）以及溶液参数，如 pH 值、REE 浓度和基质复杂性（离子强度和竞争离子）。本综述重点介绍了已发表的基于藻类的 REE 吸附研究中实验条件的差异及其对吸附效率的影响。由于从实际废物中回收 REE 的藻类吸附剂研究仍处于起步阶段，因此仍有许多方面（如实际应用的经济可行性）尚未得到探索。然而，已经有人提出将 REE 回收纳入藻类生物炼制概念中，以提高工艺的经济性（通过提供一系列其他产品），同时也为实现碳中和（因为大规模藻类养殖可以作为 CO2 的汇）。
