The preparation of a novel iron/manganese binary oxide for the efficient removal of hexavalent chromium [Cr(vi)] from aqueous solutions

Chuanxi Yang; Tiantian Ju; Xiaoning Wang; Yujia Ji; Cheng Yang; Haojie Lv; Ying Wang; Wenping Dong; Feng Dang; Xifeng Shi; Weiliang Wang; Yuqi Fan

doi:10.1039/c9ra10558a

The preparation of a novel iron/manganese binary oxide for the efficient removal of hexavalent chromium [Cr(vi)] from aqueous solutions

RSC Adv. 2020 Mar 12;10(18):10612-10623. doi: 10.1039/c9ra10558a. eCollection 2020 Mar 11.

Authors

Chuanxi Yang^{1

2}, Tiantian Ju³, Xiaoning Wang⁴, Yujia Ji⁵, Cheng Yang⁶, Haojie Lv¹, Ying Wang¹, Wenping Dong⁷, Feng Dang⁸, Xifeng Shi⁹, Weiliang Wang^{1

10}, Yuqi Fan¹

Affiliations

¹ Institute of Environment and Ecology, Shandong Normal University Jinan 250358 China [email protected] [email protected] +86-531-8618-2550.
² College of Resources and Environmental Sciences, China Agricultural University Beijing 100193 China.
³ Construction Project Environmental Assessment Service Center of Shandong Province Jinan 250012 China.
⁴ School of Mechanical Engineering and Automation, Northeastern University Shenyang 110819 China.
⁵ College of Art and Science, University of Vermont Burlington VT 05405 USA.
⁶ School of Physics and Electronics, Shandong Normal University Jinan 250014 China.
⁷ Shandong Academy of Environmental Science Co., Ltd. Jinan 250013 China.
⁸ Key Laboratory for Liquid-Solid Structural Evolution and Processing of Materials, Shandong University Jinan 250061 China.
⁹ College of Chemistry, Chemical Engineering and Materials Science, Shandong Normal University Jinan 250014 China.
¹⁰ College of Geography and Environment, Shandong Normal University Jinan 250358 China.

Abstract

To remove hexavalent chromium Cr(vi) efficiently, a novel Fe-Mn binary oxide adsorbent was prepared via a "two-step method" combined with a co-precipitation method and hydrothermal method. The as-prepared Fe-Mn binary oxide absorbent was characterized via transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier-transform infrared spectra (FTIR), thermogravimetric analysis (TGA), zeta potential, BET and X-ray photoelectron spectroscopy (XPS). The results indicated that the morphology of the adsorbent was rod-like with length of about 100 nm and width of about 50-60 nm, specific surface area was 63.297 m² g^-1, has the composition of α-Fe₂O₃, β-MnO₂ and MnFe₂O₄ and isoelectric point was observed at pH value of 4.81. The removal of Cr(vi) was chosen as a model reaction to evaluate the adsorption capacity of the Fe-Mn binary oxide adsorbent, indicating that the Fe-Mn binary oxide adsorbent showed high adsorption performance (removal rate = 99%) and excellent adsorption stability (removal rate > 90% after six rounds of adsorption). The adsorption behavior of the Fe-Mn binary oxide was better represented by the Freundlich model (adsorption isotherm) and the pseudo-second-order model (adsorption kinetic), suggesting that the adsorption process was multi-molecular layer chemical adsorption. The possible adsorption mechanism of the Fe-Mn binary oxide for the removal of Cr(vi) included the protonation process and the electrostatic attraction interactions.