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Issue 1, 2017
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Mechanistic insights into the decontamination of Th(IV) on graphene oxide-based composites by EXAFS and modeling techniques

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Abstract

The sorption mechanism of Th(IV) on amidoxime/graphene oxide composites was investigated by extended X-ray absorption fine structure (EXAFS) spectra and surface complexation modeling. It was found that amidoxime/graphene oxide composites possessed a variety of oxygen- and nitrogen-containing functional groups such as hydroxyl, carboxyl, carbonyl, amine and imine groups. The sorption kinetics and sorption isotherms of Th(IV) on amidoxime/graphene oxide composites can be satisfactorily fitted by the pseudo-second-order kinetic model and the Langmuir model, respectively. The maximum sorption capacity of Th(IV) on amidoxime/graphene oxide composites calculated from the Langmuir model at pH 2.0 and 293 K was 123.46 mg g−1. According to EXAFS analysis, the presence of a Th–C shell (R = 2.97 Å, CN = 4.9) indicated that inner-sphere surface complexation dominated the sorption of Th(IV) on amidoxime/graphene oxide composites at pH 2.0, whereas the occurrence of a Th–Th shell revealed that a surface precipitate dominated the sorption of Th(IV) on amidoxime/graphene oxide composites at pH 5.0. The pH-dependent sorption behaviors of Th(IV) on amidoxime/graphene oxide composites can be satisfactorily simulated by double layer modeling based on two inner-sphere surface complexes and a surface precipitate. These observations revealed that the amidoxime/graphene oxide composites can be regarded as a promising adsorbent to remove tetravalent radionuclides from aqueous solutions in environmental cleanup.

Graphical abstract: Mechanistic insights into the decontamination of Th(iv) on graphene oxide-based composites by EXAFS and modeling techniques

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Publication details

The article was received on 08 Oct 2016, accepted on 09 Nov 2016 and first published on 10 Nov 2016


Article type: Paper
DOI: 10.1039/C6EN00470A
Citation: Environ. Sci.: Nano, 2017,4, 222-232
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    Mechanistic insights into the decontamination of Th(IV) on graphene oxide-based composites by EXAFS and modeling techniques

    Y. Sun, X. Wang, W. Song, S. Lu, C. Chen and X. Wang, Environ. Sci.: Nano, 2017, 4, 222
    DOI: 10.1039/C6EN00470A

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