SCARCE team members recently published two articles in International peer reviewed journals on the use of microfluidic lab-on-chip for the recycling of electronic wastes.
First publication: Microfluidic Lab-on-Chip Advances for Liquid-Liquid Extraction Process Studies
The ever-increasing complexity of industrial products’ recycling calls for more efficient purification processes such as liquid/liquid extraction. Because of the high complexity of liquid/liquid extraction, optimizing a large-scale extraction is both time and resource consuming and can only be justified to solve high volume and value purification problems. It is therefore difficult to apply to small scale and highly variable waste material influx. We believe that using a fully automated and integrated microfluidic approach will enable fast and cost-effective studies of liquid/liquid extraction processes. This review presents an overview of liquid/liquid metal extraction performed using microfluidics platforms. We first give an overview of the extraction methods. We then review the most relevant characterization methods that have been integrated with such platforms.
Second Publication: A microfluidic study of synergic liquid–liquid extraction of rare earth elements
A microfluidic technique is coupled with X-ray fluorescence in order to investigate the origin of the so-ca/lled synergy effect observed in liquid–liquid extraction of rare earth elements (REEs) when special combinations of two extractants – one solvating and one ionic – are used. The setup enables kinetic studies by varying the two phases’ contact time. The results obtained are compared with those obtained using a standard batch extraction method at identical contact time. We then determine variations of free energies of transfer for five rare earth elements present in a solution together with a non-target ion (Fe3+) at different pH. Analysis of the effect of temperature and of surface charge density of the coexisting cations allows separating electrostatic effects from complexation effects. We finally show that all non-linear (synergic) effects are quadratic in mole fraction. This demonstrates that in-plane mixing entropy of the bent extractant film, in the first nanometer around rare earth ions, is the determining term in the synergy effect. Surprisingly, even when the third phase is present, free energies of transfer could still be measured in the dilute phase, which is reported for the first time, to our knowledge. We hence show that the extractive power of the dense third phase is stronger than that of conventional reverse aggregates in equilibrium with excess water. read more