Enhanced removal of aqueous Cr(VI) by the in-situ iron-loaded activated carbon through a facile impregnation with Fe(II) and Fe(VI) two-step method: Mechanism study

doi:10.21203/rs.3.rs-1947252/v1

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Research Article

Enhanced removal of aqueous Cr(VI) by the in-situ iron-loaded activated carbon through a facile impregnation with Fe(II) and Fe(VI) two-step method: Mechanism study

https://doi.org/10.21203/rs.3.rs-1947252/v1

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Journal Publication

published 29 Dec, 2022

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In this study, a novel in-situ iron-loaded activated carbon (AFPAC) was prepared by a FeSO₄/K₂FeO₄ impregnation and oxidation combination two-step supported on activated carbon for enhanced removal of Cr(VI) from aqueous solutions. Compared with fresh activated carbon, Cr(VI) removal efficiency by AFPAC increased by more than 70% under the same conditions, which due to rich iron oxides formed in-situ and synergistic effect between iron oxides and activated carbon. Cr(VI) adsorption behaviors on AFPAC under different water quality parameters were investigated. Multiple adsorption mechanisms of Cr(VI) removal by AFPAC included electrostatic attraction, redox reaction, coordinate complexation and co-precipitation. Cr(VI) adsorption process on AFPAC consisted of the three reaction steps: (1) fast protonation and electrostatic adsorption, (2) reduction of Cr(VI) into Cr(III) through at least two ways, (3) formation of inner-sphere complexes and then co-precipitation.

In-situ iron-loaded activated carbon

Iron (hydrogen) oxides

Potassium ferrate

Hexavalent chromium

Multiple mechanisms

Reaction steps