Small Angle X-Ray Scattering Study of The Porosity in Charcoals
Keywords:Quercus alba, Carya ovata, charcoal, X-ray analysis, ultrastructure, cell-wall porosity
AbstractSmall angle X-ray scattering data have been obtained for a series of charcoal samples produced by heating in a laboratory furnace under conditions chosen to simulate those encountered in commercial kilns. The scattering curves suggest that the samples contain three types of pores: (1) relatively large pores, with dimensions of the order of a few microns, which are similar to the pores in the lignincellulosic skeleton of the wood from which the charcoal was made; (2) platelet-like pores, with one dimension that does not exceed 2 or 3 nm and with the other two average dimensions being considerably larger; and (3) small pores, which have no dimensions greater than about 1 or 2 nm. For charcoals heated to 400 C, only the large pores are present in appreciable numbers. As the maximum heating temperature is increased, the platelet and small pores make an increasing contribution to the scattering. Estimates have been made of the fraction of the volume of the porous charcoal occupied by each of the three types of pores.
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