Increasing the selectivity and efficiency of ozone bleaching in a TCF sequence. Part C

Ozone appears to be an effective choice for developing new totally chlorine free (TCF) sequences. One of the goals of current research into the use of ozone as a pulp-bleaching agent is to increase the selectivity of the process. In this work, various reagents were used as additives in the ozone bleaching stage (Z) with a view to raising its selectivity. Overall 16 different reagents were used under variable conditions and various properties of the resulting pulp (Kappa number, viscosity and brightness), in addition to the Z stage selectivity and the P stage efficiency, were determined. Based on the results, the additives studied exert a favourable effect on the process (particularly oxalic acid). The performance of the reagents are analysed through the study of chain scission number (CS) in the cellulose chain.