Cerium recovery from aqueous solutions by bio/adsorption: A review in a circular economy context

Cerium is a rare earth element (REE) that stands out as an essential component in many high-tech applications. As its demand has increased in recent years, it is necessary to develop researches towards the sustainable recovery from secondary sources to reduce environmental damages and ensure its future availability. Some techniques can be applied to recover cerium, and bio/adsorption is considered a consolidated and feasible alternative for being simple, inexpensive, and highly efficient. This review presents an overview of recent published studies regarding cerium recovery by different bio/adsorbents in a circular economy context. For this purpose, recently studies on batch systems were highlighted. Kinetics, equilibrium, thermodynamic, desorption, and selectivity aspects were discussed. It can be concluded based on large literature research that the kinetics and equilibrium bio/adsorption of cerium were followed mainly by pseudo-second order and Langmuir models, respectively. Cerium bio/adsorption was spontaneous and endothermic in nature. Also, in most cases, acidic media were the main eluents used for cerium desorption. Studies involving the capture of cerium in dynamic systems were also evaluated, aiming at the scaling of bio/adsorptive processes for real applications. Finally, challenges and future prospects of research on cerium bio/adsorption were addressed.