FORMATION AND DEGRADATION OF HEXENURONIC ACID IN KRAFT COOKING AND BLEACHING
The formation and degradation of hexenuronic acid (HexA) in kraft cooking was studied with Eucalyptus camaldulensis, Acacia mangium and Scandinavian softwood mixture. Hexenuronic acid is formed rapidly during the initial phase of cooking. It is relatively stable in kraft cooking and its content drops markedly only in late residual delignification phase. The content of hexenuronic acid in pulp depends on the xylan content of raw material, uronic acid content in xylan and finally cooking conditions. About 50% of 4-O-Me-glucuronic acid units in pulp seem to convert to hexenuronic acid; there are other degradation routes. Very clearly hexenuronic acid stabilizes xylan towards alkaline peeling reaction. Normal ECF bleaching removes 95% of hexenuronic acid. After light ECF bleaching the HexA content can be high, without any adverse effects in bleached pulp.
ECF bleaching hezenuronic acid zylan
Raimo Malinen
Pulp and Paper Technology, Asian Institute of Technology (AIT), Thailand
国际会议
广州
英文
178-184
2006-11-08（万方平台首次上网日期，不代表论文的发表时间）