Issue 4, 2018

Highly efficient α-Mn2O3@α-MnO2-500 nanocomposite for peroxymonosulfate activation: comprehensive investigation of manganese oxides

Abstract

In this paper a nanorod α-Mn2O3@α-MnO2-500 nanocomposite demonstrated the highest efficiency and remarkable stability in persulfate activation compared with other manganese oxide based catalysts including α-MnO2, β-MnO2, γ-MnO2, δ-MnO2, α-Mn2O3, Mn3O4, etc. This catalyst was easily fabricated using one spot calcination treatment at 500 °C, and a minimal amount of leached Mn ions was detected during the degradation of organic contaminants. The significant performance in persulfate activation was elucidated from the unique structure and physical-chemical properties of α-Mn2O3@α-MnO2-500. Evidenced by XRD and HRTEM, α-Mn2O3@α-MnO2-500 consisted of a well mixed phase structure of tetragonal α-MnO2 and cubic α-Mn2O3 with high crystalline quality. XPS and the inhibition effect by phosphate confirmed the existence of surface hydroxyl groups (0.926 mmol g−1) on α-Mn2O3@α-MnO2-500, while FTIR, Raman and ionic strength experiments further demonstrated that the formation inner-sphere interaction was the key step in PMS activation. Supported by XPS and CV, the mixed valence states in the α-Mn2O3@α-MnO2-500 nanocomposite exhibited a more effective redox property, which favored electron transfer between Mn species (MnIV ↔ MnIII), and generated SO4˙, ˙OH and even 1O2 for the degradation of various hydrocarbon contaminants. Also, the activation energy of α-Mn2O3@α-MnO2-500/PMS for phenol degradation was only 24.7 kJ mol−1, much lower than that of α-MnO2 (38.7 kJ mol−1) and α-Mn2O3 (44.9 kJ mol−1). This Mn catalyst with much lower toxicity can be considered as a green approach in environmental remediation.

Graphical abstract: Highly efficient α-Mn2O3@α-MnO2-500 nanocomposite for peroxymonosulfate activation: comprehensive investigation of manganese oxides

Supplementary files

Article information

Article type
Paper
Submitted
09 Sep 2017
Accepted
10 Dec 2017
First published
12 Dec 2017

J. Mater. Chem. A, 2018,6, 1590-1600

Highly efficient α-Mn2O3@α-MnO2-500 nanocomposite for peroxymonosulfate activation: comprehensive investigation of manganese oxides

A. Khan, H. Wang, Y. Liu, A. Jawad, J. Ifthikar, Z. Liao, T. Wang and Z. Chen, J. Mater. Chem. A, 2018, 6, 1590 DOI: 10.1039/C7TA07942G

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