TY - JOUR
T1 - Effect of ionic Fe(III) doping on montmorillonite for photocatalytic reduction of Cr(VI) in wastewater
AU - Zhang, Li
AU - Chuaicham, Chitiphon
AU - Balakumar, Vellaichamy
AU - Sasaki, Keiko
N1 - Funding Information:
The authors would like to thank the Nanotech Center, Kyushu University for the XPS measurements.
Funding Information:
The work was supported by the Japan Society for the Promotion of Science (JSPS) KAKENHI (A) [No. JSPS JP19F19393] and Kyushu University (Progress 100) to KS. This work was supported by the nanotech platform at Kyushu University with proposal No. S-20-KU-0001.
Publisher Copyright:
© 2022 Elsevier B.V.
PY - 2022/8/1
Y1 - 2022/8/1
N2 - The potential photocatalytic activity of Mt (montmorillonite) after Fe(III) doping was measured for the photocatalytic remediation of hexavalent chromium (Cr(VI)). Mt was modified with Fe(III) at pH = 2 with IAP ≤ 1.5 ∙ 10–38 < Ksp(Fe(OH)3) = 6.0 ∙ 10 -38 to prevent the precipitation of Fe(OH)3. Doped ionic Fe(III) was located mainly in the interlayer space but presented partially on the Mt layers. XRD, FTIR, XPS and XANES/EXAFS analyses suggested that Fe(III) should exist in the cationic form. The photocatalytic characterization of the obtained Fe/ Mt suggests that Mt gained photocatalytic activity after Fe(III) ion doping. The photocatalytic transformation of Cr(VI) to harmless trivalent chromium (Cr(III)) on Fe/ Mt was also dominated by Fe(III) doping on the Mt interlayer and Mt aluminosilicate layers. Higher Fe(III) doping correlated with higher photocatalytic efficiency with the Fe(III) adsorbed on Mt at a ratio lower than 0.274 mmol/g. A further intercalation of Fe(III) reduced the photocatalytic efficiency, which could be attributed to the excess Fe(III) providing a recombination state for the electrons, trapping the electrons from the Cr(VI) reduction, and the extra Fe(III) overlapping with the active sites receiving irradiation. Based on the characterization and photocatalytic activity test, the mechanism of the photocatalytic property of Fe(III)-doped Mt was revealed for the first time. The new Fermi level formed between the forbidden bands narrowed the band gap of Mt, endowing the Mt with photocatalytic activity. This finding may contribute to explaining the role of Fe/ Mt in Fe/ Mt-based photocatalytic composites.
AB - The potential photocatalytic activity of Mt (montmorillonite) after Fe(III) doping was measured for the photocatalytic remediation of hexavalent chromium (Cr(VI)). Mt was modified with Fe(III) at pH = 2 with IAP ≤ 1.5 ∙ 10–38 < Ksp(Fe(OH)3) = 6.0 ∙ 10 -38 to prevent the precipitation of Fe(OH)3. Doped ionic Fe(III) was located mainly in the interlayer space but presented partially on the Mt layers. XRD, FTIR, XPS and XANES/EXAFS analyses suggested that Fe(III) should exist in the cationic form. The photocatalytic characterization of the obtained Fe/ Mt suggests that Mt gained photocatalytic activity after Fe(III) ion doping. The photocatalytic transformation of Cr(VI) to harmless trivalent chromium (Cr(III)) on Fe/ Mt was also dominated by Fe(III) doping on the Mt interlayer and Mt aluminosilicate layers. Higher Fe(III) doping correlated with higher photocatalytic efficiency with the Fe(III) adsorbed on Mt at a ratio lower than 0.274 mmol/g. A further intercalation of Fe(III) reduced the photocatalytic efficiency, which could be attributed to the excess Fe(III) providing a recombination state for the electrons, trapping the electrons from the Cr(VI) reduction, and the extra Fe(III) overlapping with the active sites receiving irradiation. Based on the characterization and photocatalytic activity test, the mechanism of the photocatalytic property of Fe(III)-doped Mt was revealed for the first time. The new Fermi level formed between the forbidden bands narrowed the band gap of Mt, endowing the Mt with photocatalytic activity. This finding may contribute to explaining the role of Fe/ Mt in Fe/ Mt-based photocatalytic composites.
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U2 - 10.1016/j.jphotochem.2022.113909
DO - 10.1016/j.jphotochem.2022.113909
M3 - Article
AN - SCOPUS:85126574362
VL - 429
JO - Journal of Photochemistry and Photobiology A: Chemistry
JF - Journal of Photochemistry and Photobiology A: Chemistry
SN - 1010-6030
M1 - 113909
ER -