Studies on Kraft and Kraft-AQ Pulping and Bleaching of Populus Deltoides

Kraft pulping process is the most dominant process used in paper industry. Extending delignification to a low kappa number is possible with the use of anthraquinone (AQ). The additions of AQ (0.1 per cent) results in a substantial increase in pulp yield and strength properties along with substantial decrease in kappa number. The present study deals with the kraft and kraft AQ pulping of Populus deltoides at various alkali doses, sulphidity and AQ doses. It has been found that anthraquinone (AQ) has a beneficial effect on both pulp yield and strength properties. Further kraft and kraft-AQ pulps were bleached with various conventional and nonconventional bleaching sequences including CEHH, OCEHED, OCEDED, and OCEDED to produce bleached pulp with ultra high brightness levels.