Self-separation of the adsorbent after recovery of rare-earth metals: Designing a novel non-wettable polymer

In solid phase extraction method, the adsorbent separation is very challenging and is one of the limiting factors for using batch process. As a solution to this problem, a self-floating (SF) adsorbent with simultaneous separation from water is developed in this study. The adsorbent has a very high performance for extracting and recovery of the rare-earth element (REEs), especially Yb3+, which has not been reported by other organic adsorbents, so far. The designed adsorbent is very low cost and can be easily prepared by using alkyl ketene dimer (AKD) as a commonly used sizing agent in pulp and paper industry. The designed polymer was used to remove La3+, Ce3+, Pr3+, Nd3+, Dy3+, and Yb3+ from aqueous solutions. The adsorption of the ions showed that REEs with smaller ionic radii have more tendencies towards the AKD-based vinylogous amide-diglycolamic acids self-floating (AVD-SF) polymer with the highest adsorption of 191.87 mg.g(-1) for Yb3+ ions at pH = 5.5. The adsorption isotherm of Yb3+ ions fitted with Freundlich model and the kinetics isotherm fitting confirmed the pseudo-second order model. The SF adsorbent was easily separated from water within 30 min. The reusability test showed that both the performance and structure are reserved after 10 cycles.

Automated summary

A self-floating adsorbent was developed to address the challenging adsorbent separation in solid phase extraction method, which efficiently extracts and recovers rare-earth elements, especially Yb3+. The adsorbent, prepared using alkyl ketene dimer, showed high adsorption capacity for REEs with smaller ionic radii.