title: An EDTA-β-cyclodextrin material for the adsorption of rare earth elements and its application in preconcentration of rare earth elements in seawater.
abstract: The separation and recovery of Rare earth elements (REEs) from diluted aqueous streams has attracted great attention in recent years because of ever-increasing REEs demand. In this study, a green synthesized EDTA-cross-linked β-cyclodextrin (EDTA-β-CD) biopolymer was prepared and employed in adsorption of aqueous REEs, such as La(III), Ce(III), and Eu(III). EDTA acts not only as cross-linker but also as coordination site for binding of REEs. The adsorption properties for the adsorption of REEs by varying experimental conditions were carried out by batch tests. The kinetics results revealed that the surface chemical sorption and the external film diffusion were the rate-determining steps of the adsorption process. The obtained maximum adsorption capacities of EDTA-β-CD were 0.343, 0.353, and 0.365mmolg(-1) for La(III), Ce(III) and Eu(III), respectively. Importantly, the isotherms fitted better to Langmuir than Freundlich and Sips models, suggesting a homogenous adsorption surface for REEs on the adsorbent. Moreover, the multi-component adsorption, which was modeled by extended Sips isotherms, revealed adsorbent's selectivity to Eu(III). More significantly, the successful recoveries of the studied ions from tap water and seawater samples makes EDTA-β-CD a promising sorbent for the preconcentration of REEs from diluted aqueous streams.
authors.affiliation: Laboratory of Green Chemistry, Department of Chemistry, Faculty of Technology, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli, Finland. Electronic address: zhao.feiping@lut.fi.
authors.forename: Feiping
authors.initials: F
authors.lastname: Zhao
authors.affiliation: Laboratory of Green Chemistry, Department of Chemistry, Faculty of Technology, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli, Finland.
authors.forename: Eveliina
authors.initials: E
authors.lastname: Repo
authors.affiliation: National & Local Joint Engineering Laboratory for New Petro-Chemical Materials and Fine Utilization of Resources, College of Chemistry and Chemical Engineering, Hunan Normal University, 410081 Changsha, China.
authors.forename: Yong
authors.initials: Y
authors.lastname: Meng
authors.affiliation: Laboratory of Green Chemistry, Department of Chemistry, Faculty of Technology, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli, Finland.
authors.forename: Xueting
authors.initials: X
authors.lastname: Wang
authors.affiliation: National & Local Joint Engineering Laboratory for New Petro-Chemical Materials and Fine Utilization of Resources, College of Chemistry and Chemical Engineering, Hunan Normal University, 410081 Changsha, China. Electronic address: dulinyin@126.com.
authors.forename: Dulin
authors.initials: D
authors.lastname: Yin
authors.affiliation: Laboratory of Green Chemistry, Department of Chemistry, Faculty of Technology, Lappeenranta University of Technology, Sammonkatu 12, FI-50130 Mikkeli, Finland. Electronic address: mika.sillanpaa@lut.fi.
authors.forename: Mika
authors.initials: M
authors.lastname: Sillanpää
keywords: Adsorption; Cyclodextrin; EDTA; Preconcentration; Rare earth elements; Seawater