STUDY OF PREPARATION OF AQUA-MESOPHASE PITCH

The preparation of aqua mesophase pitch (AMP) was investigated by oxidation of coal tar pitch with mixtures of concentrated sulfuric acid and nitric acid. Oxidation conditions (temperature, concentration of nitric acid in the mixed acids, oxidation time and amount of mixture of acids used) were studied in detail for their effects on the yields of AMP at different pH. It was found through FT IR spectroscopy and chemical analysis that solubility of the AMP in alkaline is a consequence of the attachment of hydrophilic groups ( OH, COOH, SO 3H, NO 2) to the pitch molecule. Oxidation temperature and content of nitric acid in mixed acids influence the yields of AMP with optimal values. AMP yields increase with increase of oxidation time or amount of mixed acids up to certain values, after which AMP yields are almost constant. The yield and composition of AMPs precipitated at different pH in a step wise manner are different.