Mössbauer and Raman characterization of iron-loaded woody charcoal: effects of Fe3+-dispersion in wood on reduction of Fe3+ and graphitization in carbonization

Abstract

An Fe3+-impregnation method was improved to disperse Fe3+ in wood powder more homogeneously, and the wood powder was carbonized at various temperatures. The obtained iron-loaded charcoal samples were analyzed using Mössbauer and Raman spectroscopy to understand the effects of the improved method on the reduction of Fe3+ and graphitization. G′(2D)-band was adopted as a marker of graphitic structure formation among Raman scattering due to sp2-carbon. Mössbauer and Raman characterization confirmed that the reduction from Fe3+ to Fe0 is closely related with the graphitization in charcoal; however, both the chemical changes progressed rapidly from a much lower temperature-range and graphitization occurred more uniformly compared with charcoal synthesized using the previous method containing no decompression-impregnation processes. Moreover, the effects of holding time at carbonization temperature and Fe3+ content in the wood powder were examined in terms of relationship between the reduction of Fe3+ and graphitization. It was suggested that there were multiple reaction paths to graphitization in carbonization.