The Topochemistry of Delignification Shown by Pulping Middle Lamella and Secondary Wall Tissue from Black Spruce Wood

Fractions of tissue from the secondary wall and middle lamella of black spruce wood were pulped by the kraft, acid-sulphite and acid-chlorite methods. In all cases, the delignification of the secondary wall tissue was more rapid than that for the middle lamella tissue. This topochemical effect was largest in kraft pulping. In acid-sulphite pulping the effect was less than in kraft, while in acid-chlorite pulping the effect was smallest. Thus the results confirmed in general the previously reported trends based on microscopic observation. However, in earlier work there was no topochemical difference found in acid-chlorite pulping, even at high delignification. In the present work, the topochemical effect in acid-chlorite pulping increased rapidly above 50% delignification.