Synthesis and characterization of magnetic mesoporous Fe3O4@mSiO2-DODGA nanoparticles for adsorption of 16 rare earth elements

Jingrui Li; Aijun Gong; Fukai Li; Lina Qiu; Weiwei Zhang; Ge Gao; Yu Liu; Jiandi Li

doi:10.1039/c8ra07762b

Synthesis and characterization of magnetic mesoporous Fe₃O₄@mSiO₂-DODGA nanoparticles for adsorption of 16 rare earth elements

RSC Adv. 2018 Nov 22;8(68):39149-39161. doi: 10.1039/c8ra07762b. eCollection 2018 Nov 16.

Authors

Jingrui Li^{1

2}, Aijun Gong^{1

2}, Fukai Li^{1

2}, Lina Qiu^{1

2}, Weiwei Zhang^{1

2}, Ge Gao^{1

2}, Yu Liu^{1

2}, Jiandi Li^{1

2}

Affiliations

¹ School of Chemistry and Biological Engineering, University of Science and Technology Beijing Beijing 100083 China Gongaijun5661@ustb.edu.cn +86-10-62334071 +86-10-82375661.
² Beijing Key Laboratory for Science and Application of Functional Molecular and Crystalline Materials, University of Science and Technology Beijing Beijing 100083 China.

Abstract

In this study, novel magnetic mesoporous Fe₃O₄@mSiO₂-DODGA nanoparticles were prepared for efficiently adsorbing and recycling REEs. Fe₃O₄@mSiO₂-DODGA was characterized by powder X-ray diffraction (XRD), transmission electron microscopy (TEM), vibrating sample magnetometry (VSM), Fourier transform infrared spectroscopy (FT-IR) and thermogravimetric analysis (TGA). The adsorption behavior of Fe₃O₄@mSiO₂-DODGA was investigated by ICP-OES. The results showed that the content of DODGA in the adsorbent was 367 μmol g^-1. Fe₃O₄@mSiO₂-DODGA exhibited the highest adsorption rates for 15 REEs, except Tm, in a 2 mol L^-1 nitric acid solution. Among these elements, the adsorption rates for Nd, Sm, Eu, Dy, Ho, Yb, Lu, Y and Sc ranged from 85.1% to 100.1%. The desorption rates for all 16 REE ions reached their maximum values when 0.01 mol L^-1 EDTA was used as the eluent. The desorption rates for Nd, Ce, Sm, Eu, Ho, Yb, Lu, Y, and Sc were 87.7-99.8%. Fe₃O₄@mSiO₂-DODGA had high stability in 2 mol L^-1 HNO₃ and could be used five times without significant loss of adsorption capacity. Moreover, these nanoparticles had high selectivity, and their adsorption rate was not affected even in a high-concentration solution of a coexisting ion. Therefore, 8 REE ions (Nd, Sm, Eu, Ho, Yb, Lu, Y, and Sc) were selected for the study of adsorption kinetics and adsorption isotherm experiments. It was demonstrated that the values of Q _e (equilibrium adsorption capacity) for Nd, Sm, Eu, Ho, Yb, Lu, Y, and Sc were 14.28-60.80 mg g^-1. The adsorption of REEs on Fe₃O₄@mSiO₂-DODGA followed the pseudo-second-order kinetic model, Elovich model and Langmuir isotherm model, which indicated that the adsorption process of Fe₃O₄@mSiO₂-DODGA for REEs comprised single-layer adsorption on a non-uniform surface controlled by chemical adsorption. It was concluded that Fe₃O₄@mSiO₂-DODGA represents a new material for the adsorption of REEs in strongly acidic solutions.