Small Angle X-Ray Scattering Study of The Porosity in Charcoals


  • J. L. Casteel
  • O. Allan Pringle
  • J. S. Lin
  • P. W. Schmidt
  • Dwight H. Slocum
  • E. Allen McGinnes, Jr.
  • Frank C. Beall


Quercus alba, Carya ovata, charcoal, X-ray analysis, ultrastructure, cell-wall porosity


Small 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.


Bragg, R. H., M. L. Hammond, J. C. Robinson, and P. L. Anderson. 1963. Small-angle scattering by pyrolytic graphite. Nature (London) 200:555-7.nCasteel, J. L., O. A. Pringle, J. S. Lin, P. W. Schmidt, D. H. Slocum, P. E. Tabirih, and E. A. Mcginnes, Jr. 1977. Small angle X-ray scattering investigation of the submicroscopic porosity of natural and irradiated wood of white oak and hickory. Unpublished report. 10 pp.nCompton, A. H., and S. K. Allison. 1935. X-rays in theory and experiment, 2nd ed., pp. 9-10. Van Nostrand, New York.nGuinier, A., G. Fournet, C. B. Walker, and K. L. Yudowitch. 1955. Small angle scattering of X-rays. J. Wiley and Sons, New York.nKratky, O., and Z. Skala. 1958. Neues Verfahren zur Herstellung von blendenstreuungsfreien Röntgen-Kleinwinkelaufnahmen. V. Ber. Bunsenges. phys. Chemie 62:73-77.nLin, J. S., C. R. Von Bastian, and P. W. Schmidt. 1974. A modified method for slit-length collimation correction in small angle X-ray scattering. J. Applied Cryst. 7:439-442.nPatel, I. S., and P. W. Schmidt. 1971. Small-angle X-ray scattering determination of the electron density of the particles in a colloidal silica suspension. J. Appl. Cryst. 7:50-55.nPons, C. H., and D. Tchoubar. 1973. Diffusion des rayons X aux petits angles produite par les defauts dans les carbones. Influence d'un système optique à fente limitèe en hauteur. C. R. Acad. Sci. Paris 277:679-681.nPringle, O. A. Jr., and P. W. Schmidt. 1977. Determination of the thickness distribution for randomly oriented, independently scattering polydisperse systems of platelets. J. Colloid Interface Sci. 60:252-7.nRuland, W. 1971. Small-angle scattering of two-phase systems: determination and significance of systematic deviations from Porod's law. J. Appl. Cryst. 4:70-73.nSchmidt, P. W. 1971. Small angle X-ray scattering from suspensions of particles. Soil Sci. 112:53-61.nTaylor, T. R., and P. W. Schmidt. 1967. A method for correcting small angle X-ray scattering curves for the effects of the width of the collimating slits. Acta Physica Austriaca 25:293-296.nVon Bastian, C. R., P. W. Schmidt, P. S. Szopa, and E. A. Mcginnes, Jr. 1972. Small angle X-ray scattering study of oak charcoals. Wood and Fiber 4:185-192.n






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