Selective Recovery of Rare Earth Elements Using a Hydroxyapatite-Chitosan Composite

Author

Zixuan XieFollow

Date of Award

Summer 8-2022

Author's School

McKelvey School of Engineering

Author's Department

Energy, Environmental & Chemical Engineering

Degree Name

Master of Science (MS)

Degree Type

Thesis

Abstract

Rare earth elements (REEs) have special properties that make them extremely important in modern clean energy technology. With rising global demand and increasing supply risks, sustainable use of rare earth resources is increasingly imperative. Coal fly ash is a promising source for recovering REEs, but the coexistence of large amounts of non-target elements requires recovery materials with a high preference for REEs. For this recovery study, we found that hydroxyapatite (HAP) that has high density of phosphate groups is efficient in selective REE recovery. The addition of chitosan (CS) as a binder increased the mechanical stability of composites and their ease of use. The synthesized HAP-CS composites showed higher selectivity for REEs than for competing cations, such as Mg²⁺, Al³⁺, and Fe³⁺, especially the divalent ion, Mg²⁺. Unlike powder- or liquid-based adsorbents, the fibrous nature of nanocomposites made their easier usage, and the addition of CS reduced the composites’ solubility, increasing their application potentials and reuse.

Language

English (en)

Chair

Young-Shin Jun

Committee Members

Srikanth Singamaneni, Yinjie Tang