The Effect of Acid Catalysis in Hot Water Pre-extraction on Soda- AQ Pulping from Kenaf Stem

In the present research, kenaf chips have been pre-extracted to weight loss levels of about 8.5, 11.5 and 14.5%, based on oven dried Kenaf chips by hot water and acid catalyzed hot water prior to pulping process. Pre-extracted and un-pretreated (control sample) Kenaf chips were converted to pulp by soda-AQ process at three cooking times 60, 90 and 120 minutes. The results of pre-extraction stage indicated that pre-extraction time to achieve a specified weight loss has been reduced with addition acid catalysis (Sulphric Acid). The results of pulping indicated that pulp yield reduced by increasing cooking time as well as weight loss of Kenaf chips in pre-extraction stage. In terms of the average pulp yield and kappa number at constant cooking time, there were significant differences at 1% error level between un-extracted (control sample) and the chips pre-extracted to 8.5, 11.5 and 14.5% weight loss. As, control pulp had highest yield and kappa number and pre-extracted pulp, at 14.5% weight loss, had lowest yield. In addition, in terms of pulp yield there were significant differences at 1% error level between un-preextracted (control) Kenaf chips and samples extracted with pure hot water and acid catalyzed hot water at any weight loss levels of 8.5, 11.5 and 14.5%. Control pulp had highest and hot water pre-extracted pulp had lowest yield. Significant differences at 1% error level were observed between control sample and pre-extracted Kenaf chips at similar amounts of weight loss in terms of average pulp kappa but there were no significant differences for average kappa number between pulps pre-extracted from hot water and acid catalyzed treatments. The results of physical and strength properties of hand sheets showed that different strength amounts were reduced by increasing the amounts of pre-extracted weight loss from 8.5 to 14.5% for all second pre-extraction methods. On the other hands, strength amounts of pulp from hot water pre-extracted Kenaf chips were often lower than pulp samples pre-extracted by acid catalyzed hot water.