ECF bleaching of Eucalypt kraft pulp-bleaching chemical needs and yellowing characteristics of different sequences

摘要

A large number of ECF bleaching sequences were used to bleach an oxygen-delignified Eucalypt kraft pulp to full brightness. An evaluation was made at a reference ISO brightness of 89/100 and different ways to reduce the use of chlorine dioxide are discussed, including the use of hydrogen peroxide, ozone and treatments in hot acidic medium. It is shown that the use of chlo- rine dioxide can indeed be reduced, but replacement of other che- micals also affects other parameters such as viscosity and yello- wing characteristics.