Simultaneous CO2 Capture and Metal Purification from Waste Streams

The process of carbon capture, which is one of the most mature yet cost-intensive technology proposed to mitigate global warming has herein been explored as a potential strategy to generate dynamic ligands for metal separation and recovery. Spontaneous CO2 fixation by industrial amines such as diethylenetriamine affords dynamic arrays of interconverting species, from which tailored subsets can be selected yielding organometallic adducts of contrasted solubility. Quantitative compositional analyses of the phases produced with varying CO2 loadings allow to elucidate the underpining self-sorting scenario induced by each metal, and to identify the conditions affording optimal individual separation by precipitation. To illustrate the potentiality of this approach, which could bring substantial added value to the CO2 capture and utilization chain value, bimetallic separation was conducted directly from exhaust gas of an internal combustrion engine vehicle, and the three constituents of the alloys used to produce the cathodes of electric vehicles were separated and recovered by successive CO2-induced selective precipitations. This study provides a potential framework to integrated CO2 capture and utilization and paves the way toward the design of CO2-sourced sustainable processes.