Author(s) Pan, S.; Li, J.; Wang, L.; Jafvert, C.T.
Journal J Colloid Interface Sci
Date Published 2019 Nov 15

Purification of water containing heavy metals that are complexed by organic chelating agents remains a challenging task. In this study, a yolk-shell FeO@hydrous zirconium oxide (Zr(OH)) sphere sphere (YHZOs) nanomaterial was evaluated for its ability to remove ethylene diamine tetraacetic acid complexed Pb (Pb-EDTA) from aqueous solution. Specifically, it is hypothesized that upon addition of HO, the FeO core of YHZOs served as a Fenton-type catalyst that results in oxidation of the Pb-complexed EDTA, and the Zr(OH) shell acted as an adsorbent, removing the released Pb from solution. From an aqueous solution containing 0.1 mM Pb-EDTA at pH 5, 0.5 g/L YHZOs, and 20 mM HO TOC reduction and Pb removal were determined to be 65.3% and 89.8%, respectively. HPLC-MS, IC and continuous flow analyzer results identified major intermediates of EDTA decay to be ethylenediaminetriacetate, (ED3A), ethylenediamine-N,N'-diacetate (ED2A), nitrilotriacetate (NTA), iminodiacetate (IDA), ethylenediamine (EDA), acetic acid, formic acid, oxalic acid, ammonia, and nitrate, with the first 5 species having some affinity to remain complexed to Pb. The adsorption of Pb onto the Zr(OH) shells was confirmed by scanning transmission electron microscopy (STEM) with mapping and X-ray photoelectron spectra (XPS). Moreover, the Pb-adsorbed YHZOs could be easily recovered due to their magnetic properties, with the Pb rinsed from them at low pH. Indeed, reused for five cycles showed only minor capacity loss. These findings suggest that the removal of chelated Pb from water, and presumably other heavy metals, by yolk-shell FeO@Zr(OH) may prove to be a useful technology for some contaminated waters.

DOI 10.1016/j.jcis.2019.08.023
ISSN 1095-7103
Citation J Colloid Interface Sci. 2019;556:6573.

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