اثر PH بر سينتيك واكنش ازن - ليگنين در مرحله رنگبري خمير كاغذ با درصد خشكي بالا

Effect of pH on Kinetics of Ozone-Lignin Reaction During Bleaching of High Consistency Paper Pulp

In this paper, the effect of [OH 7 and ozonation time on the kappa number, bleaching index and holocellulose content of high consistency paper kraft pulp of softwood is investigated. For this propose, a pulp of 33% consistency prewashed with acetic acid solution, ozonated at 20 g/Nm^3concentration at 20°C in a semi-batch reactor of 0.5 litre was used At the pH between 2-3 and for short ozonation times, the maximum deligncation and selectivity was observed. The pH dependence of the kinetic constants of "ozone-lignin" and "ozone-holocellulose" reactions at 20°C with respect to the elementary first order kinetic model (using least-square method) were obtained as follows: kL =2.341*103[oH^]^-0.032 kH =7.943*10^4[OH-]^-0.221