Effect of iron substitution in cryptomelane on the heterogeneous reaction with isoprene
Journal Article
·
· Journal of Hazardous Materials
- South China University of Technology (SCUT), Guangzhou (China); Guangzhou Higher Education Mega Centre, Guangzhou (China); OSTI
- South China University of Technology (SCUT), Guangzhou (China)
- Chinese Academy of Sciences (CAS), Ganzhou (China)
- Southwest University of Science and Technology, Mianyang (China)
- South China University of Technology (SCUT), Guangzhou (China); Guangzhou Higher Education Mega Centre, Guangzhou (China)
- University of Connecticut, Storrs, CT (United States)
Biogenic isoprene is an important pollutant for regional air quality. Being ubiquitously distributed on the earth surface, manganese (hydr)oxides should play a vital role in the transformation of isoprene. Cryptomelane is a typical manganese oxide with isomorphous substitution of Fe for Mn, but less attention has been paid to its heterogeneous reaction with isoprene. When Fe3+ replaces Mn3+, K+ is depleted and Mn3+ is oxidized to Mn4+. In contrast, oxygen vacancies are formed when Fe3+ substitutes Mn4+. Fe substitution creates weak crystallites and abundant mesopores, resulting in the increase of isoprene adsorption. As found by theoretical calculations, the Mn4+–O2- bonds at the cross sections of the tunnels is more active than that on the outer wall of the tunnels. After the adsorption of isoprene, bridging carboxylate species and hydrogen-bonding water are produced and the surface octahedra are distorted, i.e., Mn4+O6 → Mn3+O6-δ. As the heat facilitates the breakage of Mn4+–O2-, the increase of environmental temperature enhances the oxidation of isoprene. Here the above findings shed light on the effect of Fe substitution in cryptomelane to enhance the oxidation of isoprene, and illustrates that heterogeneous reaction with isoprene impairs the transformation of other environmental substances on cryptomelane.
- Research Organization:
- University of Connecticut, Storrs, CT (United States)
- Sponsoring Organization:
- China Postdoctoral Science Foundation; Guangdong Basic and Applied Basic Research Foundation; National Natural Science Foundation of China; USDOE Office of Science (SC), Basic Energy Sciences (BES). Chemical Sciences, Geosciences & Biosciences Division (CSGB)
- Grant/Contract Number:
- FG02-86ER13622
- OSTI ID:
- 1977299
- Journal Information:
- Journal of Hazardous Materials, Journal Name: Journal of Hazardous Materials Journal Issue: C Vol. 437; ISSN 0304-3894
- Publisher:
- ElsevierCopyright Statement
- Country of Publication:
- United States
- Language:
- English
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