Electrochemical oxidation of acidic Alberta coal slurries

Abstract

The electrochemical oxidation of four different types of Alberta coals of bituminous and subbituminous rank have been studied in 1 M H2SO4 slurries at 90°C under potentiostatic conditions at an applied potential of 1.0 V with respect to RHE. Two particle sizes (>200 and <60 mesh) were used to determine the rate constant for the electrochemical oxidation of coal mediated by Fe3+. Two rate constants,k c.1, andk c.2, representing initial (0-∼6 h) and subsequent (∼6–24 h) stages of electrochemical oxidation of coal, respectively, were observed. A correlation between the rate constants and the fixed carbon content (rank) of the coals was drawn. Gas chromatographic analysis of the gaseous oxidation products indicated the production of carbon dioxide. The rate and current efficiency for this production was determined as a function of electrolysis time with the rate of production reaching a steady-state level after a few hours of electrolysis. Possible mechanisms, for the oxidation of coal are discussed, based on structural and functional group models.