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.

Solvent extraction fractionation of manganese, cobalt, nickel and lithium using ionic liquids and deep eutectic solvents

“…However, hydrophobic ILs are still expensive. Moreover, the use of fluorinated atoms is unfavorable in terms of toxicity (Schaeffer et al, 2018). But the use of ILs could be justified by an increase of both the metal extraction efficiency and selectivity of the process as compared to processes based on molecular diluents.…”

The Role of Charge Transfer in the Formation of Type I Deep Eutectic Solvent-Analogous Ionic Liquid Mixtures

“…Ionic liquids (ILs) are ionic solutions composed of non-symmetric ions with low lattice energy that are liquid below an arbitrarily accepted threshold of 373 K. ILs are often referred to as “designer solvents” due to their wide range of accessible properties, which can be freely modulated by careful selection of the anion and cation [1]. These tuneable solvents are of interest for a wide range of applications, including synthesis, catalysis [1], energy storage [2], metal extraction and separation [3], carbon capture [4], and biomass dissolution [5] amongst others. A natural extension of the design versatility of ILs is the further fine-tuning of their physicochemical properties through the use of binary mixtures of these substances, which are also referred to as eutectic ILs [6,7,8,9,10,11].…”

Green solvents in urban mining

“…This mini-review pinpoints two challenges: the use of green solvents and the need to adapt recycling processes to the ever changing nature and composition of wastes. For example, WEEE are hard to define, partly because of an increasing variety of connected objects [2,5,44], connected socks being one of the last innovations in this moving field. In the near future, new focuses will emerge, such as butts.…”