Impact of dissolved organic matter in hydrogen peroxide reinforced alkaline extraction stages

摘要

It has been demonstrated in previous studies that carryover of dissolved organic matter to a following bleaching stage has a significant impact in particular on the reactions in oxygen delignification and chlorine dioxide stages. Since hydrogen peroxide is commonly used in the bleach plant in various positions, the present study was conducted in order to investigate the impact of dissolved matter on the performance of a hydrogen peroxide reinforced alkaline extraction stage. The results of a study using an OD(EP) bleaching sequence showed that in particular chlorine dioxide filtrates have a negative impact on delignification and brightening. In the case studied, the kappa number after the laboratory (EP)-stage was up to 26% higher and the brightness was up to 10 % ISO lower when carryover of dissolved matter from a chlorine dioxide stage was present. Compensating for these reductions by increasing the sodium hydroxide charge improved the brightness significantly less than the delignification.