Chemical processes of Cr(VI) removal by Fe-modified biochar under aerobic and anaerobic conditions and mechanism characterization under aerobic conditions using synchrotron-related techniques

Su, Chunli; Wang, Sheng; Zhou, Ziyi; Wang, Hongjie; Xie, Xianjun; Yang, Yanyuan; Feng, Yujie; Liu, Wenfu; Liu, Peng

doi:10.1016/j.scitotenv.2020.144604

Cited by 46 publications

(16 citation statements)

References 68 publications

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“…(2) the Cr(VI) adsorbed on MBTS was reduced to Cr(III); and (3) the chelation reaction between Cr(III) and amino groups of MBTS. The responsible groups for the reduction in Cr(VI) to Cr(III) are shown below in Equation (9) to Equation (13) [35,48].…”

Section: Adsorption Mechanismmentioning

confidence: 99%

Facile Synthesis of Magnetic Biochar Derived from Burley Tobacco Stems towards Enhanced Cr(VI) Removal: Performance and Mechanism

et al. 2022

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In this study, ferric-loaded magnetic burley tobacco stem biochar (MBTS) was synthesized via pyrolysis to improve the removal of Cr (VI). The results showed that MBTS had an adsorption capacity of 54.92 mg Cr (VI)/g, which was about 14 times higher than raw burley tobacco stem biochar (i.e., 3.84 mg/g). According to the findings obtained, a three-step mechanism of Cr (VI) removal by MBTS was further put forward, i.e., (1) Cr (VI) exchanged with hydroxyl groups on MBTS, (2) the reduction in Cr (VI) to Cr (III) mediated by oxygen-containing groups, and (3) the chelation of produced Cr (III) with the amino groups on MBTS. FTIR spectra further revealed that C-N, C-H, and C=C groups played an important role in Cr (VI) removal. Furthermore, the adsorption equilibrium and kinetics of Cr (VI) on MBTS could better be described by the Langmuir equation and pseudo-second-order rate equation. This study clearly demonstrated that ferric-loaded biochar derived from burley tobacco stems could serve as a cost-effective magnetic adsorbent for the high-efficiency removal of soluble Cr (VI) from wastewater. Tobacco stem-adsorbed Cr (VI) realized a green path for treating waste by waste.

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Section: Adsorption Mechanismmentioning

confidence: 99%

Facile Synthesis of Magnetic Biochar Derived from Burley Tobacco Stems towards Enhanced Cr(VI) Removal: Performance and Mechanism

et al. 2022

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“…Since Fe(II) and Mn(II) have a similar outer electron arrangement and similar coordination environment, in this research, the formation of MnFe 2 O 4 is regarded as the result of the substitution of Fe(II) by Mn(II) in the FeO 6 octahedron structure of FeFe 2 O 4 . The bond length is one of the critical properties to evaluate the formation priority of a crystal. , The shorter bond length of the crystal means lower lattice constant and smaller expansion volume, resulting in a lower formation energy . According to the DFT calculation results, the bond lengths of Mn–O (2.01 Å) of MnFe 2 O 4 in MnO 6 octahedron are shorter than those of Fe–O (2.05 Å) and Ce–O (2.18 Å) in FeO 6 and CeO 6 octahedrons of FeFe 2 O 4 and CeFe 2 O 4 , respectively, resulting in the lower formation energy of MnFe 2 O 4 (−57.12 eV) than those of FeFe 2 O 4 (−52.22 eV) and CeFe 2 O 4 (−49.56 eV).…”

Section: Resultsmentioning

confidence: 99%

“…The bond length is one of the critical properties to evaluate the formation priority of a crystal. 53,54 The shorter bond length of the crystal means lower lattice constant and smaller expansion volume, resulting in a lower formation energy. 52 S7.…”

Section: Effects On Ceomentioning

confidence: 99%

Selective Leaching of Rare Earth Elements from Ion-Adsorption Rare Earth Tailings: A Synergy between CeO₂ Reduction and Fe/Mn Stabilization

Zhou

Xiao

Guo

et al. 2021

Environ. Sci. Technol.

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The increasing demand for rare earth elements (REEs) motivates the development of novel strategies for cost-effective REE recovery from secondary sources, especially rare earth tailings. The biggest challenges in recovering REEs from ion-adsorption rare earth tailings are incomplete extraction of cerium (Ce) and the coleaching of iron (Fe) and manganese (Mn). Here, a synergistic process between reduction and stabilization was proposed by innovatively using elemental sulfur (S) as reductant for converting insoluble CeO 2 into soluble Ce 2 (SO 4 ) 3 and transforming Fe and Mn oxides into inert FeFe 2 O 4 and MnFe 2 O 4 spinel minerals. After the calcination at 400 °C, 97.0% of Ce can be dissolved using a diluted sulfuric acid, along with only 3.67% of Fe and 23.3% of Mn leached out. Thermodynamic analysis reveals that CeO 2 was indirectly reduced by the intermediates MnSO 4 and FeS in the system. Density functional theory calculations indicated that Fe(II) and Mn(II) shared similar outer electron arrangements and coordination environments, favoring Mn(II) over Ce(III) as a replacement for Fe(II) in the FeO 6 octahedral structure of FeFe 2 O 4 . Further investigation on the leaching process suggested that 0.5 mol L −1 H 2 SO 4 is sufficient for the recovery of REEs (97.0%). This research provides a promising strategy to selectively recover REEs from mining tailings or secondary sources via controlling the mineral phase transformation.

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“…Surface modification is an attractive method to adjust the surface properties of magnetic biochar and improve its adsorption performance [ 18 , 19 ]. Several studies have shown that biochar improved by adsorbed metals, such as Cu [ 20 ], Mn [ 21 ], Fe [ 22 ], Si [ 23 ], Ti [ 24 ], and Mg [ 21 ], has incredible high pollutant removal performance. Calcium is an abundant natural resource, which is ecologically non-toxic, thus rendering it as an attractive modifier [ 14 ].…”

Section: Introductionmentioning

confidence: 99%

Enhanced Removal of Malachite Green Using Calcium-Functionalized Magnetic Biochar

Wang

Chen

Zhang

et al. 2022

IJERPH

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To efficiently remove malachite green (MG), a novel calcium-functionalized magnetic biochar (Ca/MBC) was fabricated via a two-step pyrolysis method. Iron-containing oxides endowed the target complexes with magnetic properties, especially the chemotactic binding ability with MG, and the addition of calcium significantly changed the morphology of the material and improved its adsorption performance, especially the chemotactic binding ability with MG, which could be confirmed through FTIR, XPS, and adsorption experiments. Electrostatic adsorption, ligand exchange, and hydrogen bonding acted as essential drivers for an enhanced adsorption process, and the maximum theoretical adsorption capacity was up to 12,187.57 mg/g. Ca/MBC maintained a higher adsorption capacity at pH = 4–12, and after five adsorption–desorption cycles, the adsorption capacity and adsorption rate of MG remained at 1424.2 mg/g and 71.21%, highlighting the advantages of Ca/MBC on adsorbing MG. This study suggests that biochar can be modified by a green synthesis approach to produce calcium-functionalized magnetic biochar with excellent MG removal capacity. The synthetic material can not only remove pollutants from water but also provide an efficient way for soil remediation.

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Chemical processes of Cr(VI) removal by Fe-modified biochar under aerobic and anaerobic conditions and mechanism characterization under aerobic conditions using synchrotron-related techniques

Cited by 46 publications

References 68 publications

Facile Synthesis of Magnetic Biochar Derived from Burley Tobacco Stems towards Enhanced Cr(VI) Removal: Performance and Mechanism

Facile Synthesis of Magnetic Biochar Derived from Burley Tobacco Stems towards Enhanced Cr(VI) Removal: Performance and Mechanism

Selective Leaching of Rare Earth Elements from Ion-Adsorption Rare Earth Tailings: A Synergy between CeO₂ Reduction and Fe/Mn Stabilization

Enhanced Removal of Malachite Green Using Calcium-Functionalized Magnetic Biochar

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Chemical processes of Cr(VI) removal by Fe-modified biochar under aerobic and anaerobic conditions and mechanism characterization under aerobic conditions using synchrotron-related techniques

Cited by 46 publications

References 68 publications

Facile Synthesis of Magnetic Biochar Derived from Burley Tobacco Stems towards Enhanced Cr(VI) Removal: Performance and Mechanism

Facile Synthesis of Magnetic Biochar Derived from Burley Tobacco Stems towards Enhanced Cr(VI) Removal: Performance and Mechanism

Selective Leaching of Rare Earth Elements from Ion-Adsorption Rare Earth Tailings: A Synergy between CeO2 Reduction and Fe/Mn Stabilization

Enhanced Removal of Malachite Green Using Calcium-Functionalized Magnetic Biochar

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Product

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Selective Leaching of Rare Earth Elements from Ion-Adsorption Rare Earth Tailings: A Synergy between CeO₂ Reduction and Fe/Mn Stabilization