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

Abstract

Phytate intercalated MgAl layered double hydroxide (MgAl-LDH) was prepared by 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 the 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), all the capture rates of the four metal ions were more than 97%, for the highly toxic Pb2+ even up to nearly 100%, and maintained a high capture rate (99.87%) for Pb2+ at a high concentration (100 mg/L). When all the four metal ions are co-exist 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 rare earth metal ions Pr3+ and Ce3+ by phytate-LDH. Based on the elemental analysis, it is found that the difference of adsorption capacities is mainly due to the different coordination number of them with phytate-LDH. With the molecular simulation, we believe that the adsorption selectivity is due to the difference of binding energy between metal ion and phytate-LDH. Therefore, the phytate-LDH is promising for the enrichment and/or purification of rare earth metal ions and removal of toxic metal ions from waste water.

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Publication details

The article was received on 23 Sep 2017, accepted on 04 Dec 2017 and first published on 04 Dec 2017


Article type: Paper
DOI: 10.1039/C7DT03583G
Citation: Dalton Trans., 2017, Accepted Manuscript
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    Enrichment of rare earth metal ions by highly selective adsorption of phytate intercalated layered double hydroxide

    C. Jin, H. Liu, X. Kong, H. Yan and X. Lei, Dalton Trans., 2017, Accepted Manuscript , DOI: 10.1039/C7DT03583G

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