화학공학소재연구정보센터
Materials Chemistry and Physics, Vol.208, 258-267, 2018
Structure and properties of vanadium-doped alpha-MnO2 and enhanced Pb2+ adsorption phenollphotocatalytic degradation
Vanadium (V)-doped cryptomelane was synthesized and characterized by powder X-ray diffraction, electron microscopy, N-2 adsorption, diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy and X-ray absorption spectroscopy. Vanadium doping does not change the basic crystal structure but slightly decreases the lattice parameters (a, b, c, beta and cell volume) and increases the coherent scattering domain (CSD) sizes (16-19 nm). These V-doped cryptomelane materials are granular particles with increased specific surface areas (149-183 m(2) g(-1)) and increased concentrations of hydroxyl groups on the surfaces with increasing V doping. Both V 2p(3/2) spectra and V K-edge X-ray absorption near edge spectroscopy indicates that V exists in +5. Substitution of V5+ for Mn4+ in cryptomelane framework results in reduction in Mn average oxidation state and increase in bond lengths of Mn-O in [MnO6] unit, edge- and corner-sharing Mn-Mn(V) pairs. These V-doped materials have greatly increased adsorption capacities for Pb2+ (937-1146 mmol kg(-1)). Doping similar to 1.4 wt.% V can significantly enhance cryptomelane optical absorption properties and thus photocatalytic degradation of phenol, i.e., with a TOC removal rate of similar to 77%. These results can facilitate the modification and application of environmental friendly Mn oxide materials in pollution control and remediation. (C) 2018 Elsevier B.V. All rights reserved.