The accumulation of coal ash waste is an environmental and economic obstacle. Herein, Al3+-substituted α-Fe2O3 nanoflakes, with a nominal formula of Fe1.72Al0.28O3 were successfully synthesized from brown coal fly ash waste. The synthesis yield reaches approximately 32 wt% on the basis of dried ash waste. During the hydrothermal process, the impure Al3+ replaced part of the Fe3+ in the hematite crystal, resulting in defect-mediated Fe1.72Al0.28O3 nanoflakes. The obtained nanoflakes possess a round-shape morphology with a diameter of around 300 nm and 50 nm in thickness. Results show that Al3+ partially substituted Fe3+ in α-Fe2O3, which is the root reason of the defects formation. In addition, the Al3+-defects changed the original atomic structure of α-Fe2O3, causing a smaller first shell for an Fe-O bond distance of 1.95(0.21) Å, and a destroyed periodical symmetry for a smaller coordination number of 4.5(0.3)) for Fe. Owing to the introduction of defects, the resultant nanoflakes showed an enhanced adsorption performance for Cr(VI), As(V), As(III) and Congo red in waste water, with the maximum adsorption capacity of 68.3, 80.6, 61.1 and 213.8 mg g-1, respectively. These values are around 3-5 times larger than that for the pure nanosized α-Fe2O3 synthesized under the same conditions.

Converting waste into worth: Fe1.72Al0.28O3 nanoflakes harvesting from brown coal fly ash with crystal defects for enhanced water remediation

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.