US EPA

2908010 

Journal Article 

The role of peroxide species in carbohydrate degradation during oxygen bleaching .2. Effect of oxygen pressure on the degradation of lignin and carbohydrate model compounds and on the reaction selectivity 

Yokoyama, T; Matsumoto, Y; Yasumoto, M; Meshitsuka, G 

1996 

Yes 

Journal of Pulp & Paper Science
ISSN: 0826-6220 

22 

5 

J151-J154 

WOS:A1996UL27400001 

A lignin model compound, 2,4,6-trimethylphenol (TMPh), and a carbohydrate model compound, methyl-beta-D-glucopyranoside (MGP), were subjected to oxygen-alkali treatment under 0.3 or 1.0 MPa of oxygen pressure and the effect of oxygen pressure on the reaction selectivity between TMPh and MGP was examined. The whole degradation pathway of TMPh was expressed by a simple formula: -d[TMPh]/dt = k[TMPh](n). The constants n were dependent on the initial concentration of both TMPh and MGP and on oxygen pressure and, in all cases examined, were smaller than 1. These results were attributed to the participation of active oxygen species produced from peroxides in TMPh degradation. The degradation of MGP in the presence of TMPh exhibited two phases: the first phase was a rapid degradation and was dependent on TMPh degradation, and the second one was quite a slow degradation taking place after the consumption of TMPh. The gradation of MGP in the first phase was simply expressed by a formula: Delta[MGP] = A x Delta[TMPh]. When oxygen pressure was increased, the constant A decreased, indicating the improvement of the reaction selectivity. In the absence of TMPh, MGP was hardly degraded under the conditions employed. 

lignin model compounds; organic compounds; liquids; peroxides; hydrogen peroxide; oxygen bleaching; pressure; oxygen; degradation; carbohydrates; model compounds; alkalis; pretreatment; kraft pulps; selectivity