Properties and application of ionic liquids in leaching base/precious metals from e-waste. A review

Electronic waste (e-waste) is the fastest-growing type of waste worldwide and contains significant levels of precious metals, rare earth elements, and basic elements that make it economically attractive. This type of waste presents a challenge in the metallurgical processing industry due to its heterogeneity, toxicity, and the environmental impact caused by its incorrect disposal by companies and individuals. Their treatment with traditional solvents that are environmentally unfriendly affects the recovery of metals. In addition the practical application, recovery and recycling of the ionic liquids (ILs) are topics that align with the circular economy context, which is imperative to address today. This study presents a comprehensive review of the use of ILs to recover metals from electronic waste, with an emphasis on the leaching stage. The advantages of using ILs in hydrometallurgy are their design properties and low toxicity, which would benefit the environment and human health. A simple economic evaluation is made to expand the use of ionic liquids in metal leaching. The physicochemical properties and their influence on the process according to the nature of the cation and anion are reported. [Display omitted] •A critical analysis on e-waste leaching with ionic liquids is presented.•Effect of anion and cation of ionic liquids in the leaching process is analyzed.•Usually, the highest extraction percentages are obtained by acid ionic liquids.•Recycling properties of ionic liquids make them competitive with traditional solvents.•Selective leaching is possible through proper selection of operating conditions.