Ultra high pressure peroxide bleaching of kraft pulps

In the past few years, environmental pressures have expanded the use of chlorine dioxide and hydrogen peroxide as bleaching and delignification agent in Kraft pulp industry. Pressurized peroxide technology is more and more involved in both ECF and TCF bleaching sequences. Since pressure and temperature boost peroxide efficiency considerably, we have particularly investigated the unexpected effect of the pressure. Our studies have been conducted until pressure as high as 10,000 kPa (100 bar) with temperature up to 150 degrees C. To avoid oxygen interference, pulps have been pressurized with hydraulic device. Addition of a stabilising agent have been investigated in order to reduce the detrimental effect of side reaction regarding pulp properties.