Recovery of metals from waste electrical and electronic equipment (WEEE) using unconventional solvents based on ionic liquids

Abstract Waste electrical and electronic equipment (WEEE) is the fastest growing type of waste globally and is an important challenge due to its heterogeneity, intrinsic toxicity and potential environmental impact. However, WEEE also represents an important secondary source of critical and valuable elements and must be viewed as a resource within the context of a circular economy. The use of ionic liquids (ILs) to recover metals from WEEE is reviewed with a special emphasis on the use of ILs in leaching and solvent extraction processes. The advantages of ILs as a reaction medium compared to existing conventional solvents lies in their tuneability and potential environmental benefits. Many studies have used ILs for the selective extraction and purification of metals from WEEE, particularly from waste fluorescent lamp phosphor and batteries containing rare-earth elements with promising results. However, significant barriers remain to the commercial use of ILs for treating WEEE and key barriers to progress are identified. In particular more focus is required to improve upstream collection and separation of WEEE, as this would greatly increase the potential to use selective, more efficient, ILs for metal recovery.