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The adsorption behavior and mechanism of Cr(VI) on 3D hierarchical α-Fe2O3 structures exposed by (0 0 1) and non-(0 0 1) planes
CEJ Chemical Engineering Journal
Format: Journal Article
Publication Year: 2017
Pages: 815 - 823
Source ID: shanti-sources-106216
Abstract: The adsorption mechanism of Cr(VI) onto different α-Fe2O3 crystal facets is chemisorption process through outer surface of doubly and triply coordinated hydroxyl groups.

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• 3D hierarchical α-Fe2O3 nanoparticles with different planes predominantly exposed were synthesized. • The Cr(VI) removal ability reach to 34.4 mg/g by flower-like α-Fe2O3 particles with (0 0 1) plane exposed. • The coordination between Cr(VI) and special doubly coordinated hydroxyl groups plays important role for adsorption.
Two kinds of 3D hierarchical α-Fe2O3 nanoparticles, flower-like structure with the (0 0 1) plane predominantly exposed on petals and urchin-like structure with nanorods grown along [0 0 1] direction, have been synthesized under the influence of glycerol by a facile hydrothermal method. It is proposed that the Fe(III)-glycerol micro-reaction units that selectively adsorb to (0 0 1) or other planes result in different morphologies. The adsorption of Cr(VI) from aqueous solution onto these α-Fe2O3 nanoparticles showed that the removal efficiency up to 98.5% and 88.8% in 25 mg/L Cr(VI) solution, and the adsorption capacity reaches to 34.4 mg/g and 26.0 mg/g without pH adjustment. The adsorption kinetic is well described by the pseudo-second-order model and the Cr(VI) adsorption on the adsorbent agrees well with the Langmuir model. Lower surface areas and more excellent adsorption property associates with the chemisorption of Cr(VI) onto α-Fe2O3 (0 0 1), which is achieved by coordination between Cr(VI) and doubly or triply coordinated hydroxyl groups on α-Fe2O3 surface.