Urban Mining of Rare Earth Elements by Rapid Optical Detection from Aqueous Solution
A rapid “on the fly”-procedure for qualitative and semi-quantitative detection of lanthanide ions was developed. Detection is based on an extremely fast complexation with 4′-phenylterpyridine in less than a second followed by an optical read-out of the resulting luminescence signal. The process enables simultaneous separation from other chemical species by thin-layer chromatography. Sensitive detection is possible in aqueous solution, for acidic conditions and the presence of heavy and transition metal ions. Therefore, the method can be used for an urban mining approach for the evaluation of an Ln3+ content in real systems, e.g. for the controlled recovery of trivalent lanthanides from wastewater or leaching solutions. Major advantages of the procedure are its accessibility, high speed, and sensitivity. Without any additives, Ln3+ concentrations of 10 µM can be detected by the eye. For solutions containing contaminants, such as transition metal ions, or for an acidic milieu, Ln3+ concentrations of 0.1 mM and thus in the range of mining water concentrations can be well detected.
Ref.: A. E. Sedykh, J. J. Pflug, T. C. Schäfer, R. Bissert, D. G. Kurth, K. Müller-Buschbaum, ACS Sustain. Chem. Eng.2022, 10, 5101-5109, DOI: 10.1021/acssuschemeng.1c07806.
