Rapid and Highly Efficient Preconcentration of Eu(III) by Core–Shell Structured Fe₃O₄@Humic Acid Magnetic Nanoparticles

Abstract

In this study, humic acid-coated Fe(3)O(4) magnetic nanoparticles (Fe(3)O(4)@HA MNPs) were synthesized using a chemical coprecipitation method and characterized in detail. The XRD analysis results showed that HA coating did not change the phase of Fe(3)O(4) cores. The TEM image suggested that Fe(3)O(4)@HA MNPs had nearly uniform size without the observation of aggregation. The Fe(3)O(4)@HA MNPs were stable in solution and could be easily separated from aqueous solution using a magnetic separation method. A batch technique was adopted to investigate the removal efficiency of Fe(3)O(4)@HA MNPs toward Eu(III) under various environmental conditions. The kinetic process of Eu(III) sorption on Fe(3)O(4)@HA MNPs reached equilibrium within <30 min. The fast sorption kinetics and high sorption amount were attributed to the plentiful surface sites provided by the surface-coated HA macromolecules. The Fe(3)O(4)@HA MNPs was able to remove ~99% of Eu(III) in aqueous solution at pH 8.5. Except for SO(4)(2-) anions, the coexisting electrolyte ions had no significant competition effects on the removal of Eu(III) by Fe(3)O(4)@HA MNPs. The obvious sorption-desorption hysteresis suggested that the removal of Eu(III) was dominated by inner-sphere surface complexation. The sorption isotherm agreed well with the Langmuir model, having a maximum sorption capacity of 6.95 × 10(-5) mol g(-1). The leaching test showed that the Eu(III)-loaded Fe(3)O(4)@HA colloids were capable to maintain high thermodynamic stability for long aging times. The findings herein suggested that Fe(3)O(4)@HA MNPs could be potentially used as a highly effective material for the enrichment and preconcentration of radionuclide Eu(III) or other trivalent lanthanides/actinides in geological repositories or in nuclear waste management.

Bionanocomposites for Magnetic Removal of Water Pollutants

“…Humic acid (HA) coated Fe 3 O 4 nanoparticles were synthesized by co-precipitation method [98] leading to a core-shell type structure. The Fe 3 O 4 @HA particles appeared as spheroidal shaped with nearly uniform sizes.…”

“…Table 4 lists the most representative isotherm and kinetic equations used for describing the adsorption of water pollutants. The Langmuir equation [47] derives from an isotherm model commonly applied to describe the equilibrium of sorption on magnetic bionanocomposites [60,40,81,102,14,104,59,98,94,26]. This empirical model assumes monolayer adsorption at a finite number of sites that are identical and equivalent, without any interaction between molecules adsorbed on adjacent sites.…”

“…The composite was able to remove over 99 % of Hg(II) and Pb(II), and over 95 % of Cu(II) and Cd(II) in natural and tap water at optimized pH. More recently, Yang et al [98] investigated the removal of Eu(III) ions from aqueous solutions by Fe 3 O 4 @HA composites. A fast sorption kinetics was observed, equilibrium reached in less than 30 min, with high sorption capacity attributed to abundant surface sites for coordination provided by the HA macromolecules.…”

Magnetite-based adsorbents for sequestration of radionuclides: a review

“…In view of this point, environmentalists synthesized humic acid-coated Fe 3 O 4 magnetic nanoparticles (Fe 3 O 4 @HA MNPs) as an adsorbent to evaluate its removal efficiency towards Eu(III) under various environmental conditions. 77 The kinetic studies showed that Eu(III) adsorption onto The synthesized adsorbent showed good recycling performance up to six cycles using 0.01 M HCl solution as an eluent. Based on the negligible leachability of Eu from the loaded adsorbent in tap water over a period of three months, the Fe 3 O 4 @HA MNPs was proposed as a highly effective material for the enrichment and pre-concentration of radionuclide Eu(III) or other trivalent lanthanides/actinides in geological repositories or in nuclear waste management.…”

Sorption and desorption properties of Eu(III) on attapulgite

“…Thereby, the research on the interaction of 152?154 Eu(III) with different kinds of oxides, clay minerals or manmade nanomaterials is important to understand the physicochemical properties of other trivalent lanthanides or actinides in the environment. The sorption of 152?154 Eu(III) on clay minerals, metal oxides and nanomaterials had been extensively studied in the last decade [7][8][9][10][11][12][13][14][15][16][17], and the results suggested that the sorption of Eu(III) was strongly dependent on ionic strength and pH at low pH values. The sorption was mainly dominated by outer-sphere surface complexation and/or ion exchange at low pH, and by inner-sphere surface complexation and/or surface (co)precipitation at high pH values.…”