Advantages with pressurised hot peroxide bleaching:
- Pressure and temperature 100-110°C (212-230°F) gives better stoichiometry and a higher bleaching rate than an athmospheric P-stage at 85-90°C (185-194°F)
- Shorter retention time: 1-2 h vs. 5-15 h in atmosphere systems
- Important stage in TCF sequences
- Can reduce the CIO2 charge and AOX levels by 50% in ECF sequences.
Pressurised peroxide stages (PO) are an advantage in totally chlorine free (TCF) bleaching by making it possible to achieve a high final brightness. In sequences with chlorine dioxide (ECF bleaching), a powerful peroxide stage will reduce the consumption of chlorine dioxide or even replace one chlorine dioxide stage.
A hot, pressurised peroxide stage operates at temperatures above 100°C (212°F) with a small amount of oxygen added. A prerequisite for successful peroxide bleaching is that the content of metal ions, e.g. manganese, copper and iron, is low.