Characterization of black liquors from soda-AQ pulping of reed canary grass (Phalaris arundinacea l.)

Reed canary grass (Phalaris arundinacea L.) was delignified in a laboratory-scale digester by conventional soda-AQ pulping under varying conditions. The chemical composition of the corresponding black liquors was analyzed with respect to their main organic constituents. The results showed that the dry solids of the black liquors contained 33-34 % lignin, 14-19 % aliphatic carboxylic acids and 1216 % polysaccharides. No significant differences were found in the average molecular masses ((M) over bar (a) 4700-5600 Da and (M) over bar (n) 650-750 Da) of the dissolved lignins in these black liquors. although the polydispersity ((M) over bar (w)/(M) over bar (n)) that the values (6.6-7.9) indicate c molecular masses had a wide distribution. Lignin clearly degraded in the black liquors as delignification proceeded. Of the monosaccharide moieties detected in the polysaccharides, xylose was predominant, suggesting that xylan was a major hemicellulose constituent in the black liquors.