Enrichment and recovery of low-concentration REEs from water using synthesized eco-friendly sodium alginate/nano-Mg(OH)2 composite beads

In the past few decades, nanomaterials have attracted great attention as promising adsorbents for the recovery of rare earth elements (REEs) from wastewater. However, there are still some shortcomings in the application of nanomaterials to the adsorption of REEs, such as poor mechanical properties, easy collapse of structure, and difficulty in collection in practical application. In this study, sodium alginate supported nano-Mg(OH)2 (SA@Mg(OH)2) composite beads were prepared by adding Ca2+ as a cross-linking agent in a mixed suspension of sodium alginate and synthesized flower-like nano-Mg(OH)2, and were applied to remove and recover the low-concentration REEs from water. The analysis of the phase component and micromorphology of the composite beads revealed that the nano-Mg(OH)2 maintained a flower-like structure and distributed homogeneously throughout the sodium alginate beads. The adsorption experiments showed that the SA@Mg(OH)2 can fully adsorb Eu(III) with an adsorption capacity up to 394.61 mg/g, and keep a good mechanism performance after adsorption without collapse of the structure. Therefore, the excellent performance of SA@Mg(OH)2 indicates that loading environmentally functional materials on sodium alginate is a promising method to accelerate the environmental application of nanomaterials in wastewater treatment.