ELECTROCHEMISTRY OF CARBONACEOUS MATERIALS .2. ANODIC ELECTROACTIVITY OF COAL SLURRIES IN 85-PERCENT PHOSPHORIC-ACID MEDIA

Current-potential curves of suspended coal (Sulcis basin, Sardinia, Italy) in 85% H3PO4 were taken on a platinum electrode at 100-degrees-C. Anodic current in the potential range of 0-1.5 V versus saturated calomel electrode was due to some humic acid-type substances released by coal in the electrolyte. The leaching of organic matter increased with the lowering of the particle dimensions, and the related oxidation currents attained stable values even during slurry formation. Current-potential curves were still unchanged when coal was filtered off from the suspension. Previous washing of ground coal with diluted mineral acids, including H3PO4, did not dissolve any significant amount of the substances responsible for the electrochemical activity of the coal sample examined.