A DENSITY GRADIENT CENTRIFUGATION METHOD FOR SEPARATION OF PEAT

The conditions necessary for a laboratory-scale separation of the prem aceral constituents of peat (i.e., the precursor to coal) are investig ated. The method used is an isopycnic density centrifugation (DGC) tec hnique aimed at isolating pure premacerals. This method, which is base d on known density differences of various macerals, has been used succ essfully in coal separations but never with peats. The technique invol ved grinding the peats in a planetary ball mill to an approximate 10 m u m average particle size and conducting dispersion tests using NaCl, Ca(NO3)(2), CsCl, and TEE as solvents coupled with numerous surfactant s. The density gradient centrifugation technique was run with both an aqueous and organic gradient using plain milled peat, demineralized pe at, and demineralized methylated peat. The best separations were achie ved in a single run if the peat was demineralized and dispersed with a wetting agent in an organic gradient. Analytical-scale separations we re used to choose the most responsive peat to be used in a preparative -scale separation. A low and high density weight fraction, analyzed by flash pyrolysis, revealed distinctly different chromatograms, indicat ing that the pear had reached a reasonable degree of separation. Four peats of differing constitution are reviewed.