AN XPS INVESTIGATION OF THE EFFECTS OF HEAT-TREATMENT ON THE CHLORINESURFACE-CHEMISTRY OF SOME LIGNITES

X-ray photoelectron spectroscopy (XPS) was used to study the conversio n of inorganic chlorine (chloride salts) to C-Cl bonds and subsequentl y chloro-organics on the surface of lignite by heat treatment at 300-d egrees-C in humid air. It is shown that a naturally chloride-rich lign ite can form chloro-organics by heat treatment without added catalysts . The XPS method was used to verify C-Cl bonds on the lignite surface as a necessary condition of chloro-organic formation according to the so-called de novo synthesis. The chloro-organics were formed in a laye r on the lignite surface with a chlorine content significantly higher than on the original surface. This implies that under the influence of air, chloride ions moved to the lignite surface, with subsequent oxid ation and formation of C-Cl bonds on the surface, allowing subsequent release of toxic PCDDs and PCDFs.