Issue 9, 2018

Enrichment of rare earth metal ions by the highly selective adsorption of phytate intercalated layered double hydroxide

Abstract

Phytate intercalated MgAl layered double hydroxide (MgAl-LDH) was prepared by an anion exchange method with the precursor NO3 containing MgAl-LDH. The final as-synthesized product [Mg0.69Al0.31(OH)2] (phytateNa6)0.05 (NO3)0.01·mH2O (phytate-LDH) has highly selective adsorption ability for some metal ions and can be used to enrich rare earth metal ions in mixed solution, such as Pr3+ and Ce3+ from a mixed solution of them with Pb2+ and Co2+. At first, phytate-LDH has good adsorption performance for these ions in single metal ion solutions. At low concentration (below 10 mg L−1), all the capture rates of the four metal ions were more than 97%, for highly toxic Pb2+ it was even up to nearly 100%, and a high capture rate (99.87%) was maintained for Pb2+ at a high concentration (100 mg L−1). When all the four metal ions are co-existing in aqueous solution, the selectivity order is Pb2+ ≫ Pr3+ ≈ Ce3+ > Co2+. In a solution containing mixtures of the three metal ions of Pr3+, Ce3+, and Co2+, the selectivity order is Pr3+ ≈ Ce3+ ≫ Co2+, and in a solution containing mixtures of Pr3+ with Co2+ and Ce3+ with Co2+, the selectivity orders are Pr3+ ≫ Co2+ and Ce3+ ≫ Co2+, respectively. The high selectivity and adsorption capacities for Pb2+, Co2+, Pr3+, and Ce3+ result in the efficient removal of Pb2+ and enrichment of the rare earth metal ions Pr3+ and Ce3+ by phytate-LDH. Based on the elemental analysis, it is found that the difference of the adsorption capacities is mainly due to the different coordination number of them with phytate-LDH. With molecular simulation, we believe that the adsorption selectivity is due to the difference of the binding energy between the metal ion and phytate-LDH. Therefore, the phytate-LDH is promising for the enrichment and/or purification of the rare earth metal ions and removal of toxic metal ions from waste water.

Graphical abstract: Enrichment of rare earth metal ions by the highly selective adsorption of phytate intercalated layered double hydroxide

Article information

Article type
Paper
Submitted
23 9 2017
Accepted
04 12 2017
First published
04 12 2017

Dalton Trans., 2018,47, 3093-3101

Enrichment of rare earth metal ions by the highly selective adsorption of phytate intercalated layered double hydroxide

C. Jin, H. Liu, X. Kong, H. Yan and X. Lei, Dalton Trans., 2018, 47, 3093 DOI: 10.1039/C7DT03583G

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