期刊
CHEMICAL ENGINEERING JOURNAL
卷 438, 期 -, 页码 -出版社
ELSEVIER SCIENCE SA
DOI: 10.1016/j.cej.2022.135498
关键词
beta-FeC2O4 center dot 2H(2)O; Chromate removal; Electron utilization efficiency; Kirkendall effect; Mutual mass diffusion process
资金
- National Science Foundation of China [21906076, 51938007, 51878325]
In this study, the removal of chromate (Cr(VI)) from simulated wastewater by beta-FeC2O4 center dot 2H(2)O was investigated. The results showed that beta-FeC2O4 center dot 2H(2)O had a high Cr(VI) removal capacity due to the reduction of Cr(VI) to Cr(III) by Fe(II). The study also revealed the mechanism of Cr(VI) removal by beta-FeC2O4 center dot 2H(2)O through careful examination of the morphology and chemical compositions of the material.
In this study, we investigated the chromate (Cr(VI)) removal from the simulated wastewater by beta-FeC2O4 center dot 2H(2)O, the maximum Cr(VI) removal capacity of beta-FeC2O4 center dot 2H(2)O was 93.6 mg/g at the initial pH values of 3.0-10.0 and electron utilization efficiencies approached nearly 100%. The morphology and chemical compositions of fresh prepared and Cr(VI)-reacted beta-FeC2O4 center dot 2H(2)O were carefully examined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), Fe-57 Mossbauer spectrum, energy dispersive X-ray analysis (EDX), and X-ray photoelectron spectroscopic (XPS) with depth profiles analysis. The results demonstrated that the Cr(VI) was efficiently removed by beta-FeC2O4 center dot 2H(2)O due to the amplified Kirkendall effect. The Cr(VI) was reduced to Cr (III) by Fe(II) when it adsorbed on beta-FeC2O4 center dot 2H(2)O. The in situ generated Cr(III) was then co-precipitated with Fe (III) to form Cr(III)/Fe(III) oxyhydroxides layer on the surface of beta-FeC2O4 center dot 2H(2)O. Meanwhile, soluble [Fe(III) (C2O42-)(2)](-) was generated and preferred to diffuse into aqueous solution. Therefore, the channel was formed for outward diffusion of [Fe(III)-(C2O42-)(2)](-). With assistance of the channel, surface absorbed Cr(VI) could move across the oxide layer facilely and get reduced at inner part. The higher diffusivity of [Fe(III)-(C2O42-)(2)](-) than Cr (VI) drave marked hollow-out phenomenon of the Cr(VI)-reacted beta-FeC2O4 center dot 2H(2)O. This mutual mass diffusion process would offset the negative effects of incrassated iron oxide shell, realizing efficient Cr(VI) removal of beta-FeC2O4 center dot 2H(2)O.
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