Issue 12, 2017, Issue in Progress

Core–shell superparamagnetic monodisperse nanospheres based on amino-functionalized CoFe2O4@SiO2 for removal of heavy metals from aqueous solutions

Abstract

To remove heavy metals from aqueous solutions, amino-functionalized superparamagnetic CoFe2O4@SiO2 (CoFe2O4@SiO2–NH2) core–shell nanospheres were designed and constructed. In particular, well-defined CoFe2O4 nanoparticles (NPs) were synthesized by reverse co-precipitation. The shell of the CoFe2O4 NPs was composed of amorphous silica (SiO2), which had a thickness of ∼35 nm. Monodisperse CoFe2O4@SiO2 nanospheres grafted with more amino groups had a greater adsorption capacity and higher removal efficiency for heavy metal ions (Cd(II): 199.9 mg g−1, 99.96%; Cu(II): 177.8 mg g−1, 88.05%; Pb(II): 181.6 mg g−1, 90.79%). The effects of the pH, initial concentrations, reaction temperature and time on the adsorption of heavy metal ions by CoFe2O4@SiO2–NH2 were analyzed systematically. The adsorption process on the nanospheres was well described by the Langmuir model. The adsorption kinetics can be best fitted by the pseudo-second-order kinetics model. Analysis of a thermodynamic study of Cu(II) showed that the process of adsorption is spontaneous and endothermic in nature. Owing to the superparamagnetic properties with a high saturation magnetization value (32.92 emu g−1) of CoFe2O4@SiO2–NH2, the metal-loaded nanospheres can be quickly removed from an aqueous solution (30 s) by magnetic separation. Moreover, the nanospheres exhibited good reusability for up to five cycles. The results confirm that the monodisperse amino-functionalized CoFe2O4@SiO2 magnetic nanospheres could be a potential adsorbent for the effective and regenerable removal of heavy metals from aqueous solutions.

Graphical abstract: Core–shell superparamagnetic monodisperse nanospheres based on amino-functionalized CoFe2O4@SiO2 for removal of heavy metals from aqueous solutions

Supplementary files

Article information

Article type
Paper
Submitted
04 Dec 2016
Accepted
04 Jan 2017
First published
20 Jan 2017
This article is Open Access
Creative Commons BY-NC license

RSC Adv., 2017,7, 6911-6921

Core–shell superparamagnetic monodisperse nanospheres based on amino-functionalized CoFe2O4@SiO2 for removal of heavy metals from aqueous solutions

C. Ren, X. Ding, H. Fu, W. Li, H. Wu and H. Yang, RSC Adv., 2017, 7, 6911 DOI: 10.1039/C6RA27728D

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