The potential of laccase to remove extractives present in pulp and white water from TMP newsprint mills

We assessed the potential of using laccase to remove extractives present in thermomechanical pulp (TMP) and white water from newsprint mills. Treatment of mechanical pulp by laccase at 50 degrees C for 2 h decreased lipophilic extractives present initially in the pulp by up to 25% and hydrophilic extractives by over 60%. Laccase treatment of pulp extractives was equally effective on pulps obtained from different wood species. When laccase treatment was applied to paper machine white water a significant reduction of white water extractives was achieved, with lipophilic extractives reduced by more than 50% and over 90% removal of hydrophilic extractives. The reactivity of laccase on wood lipophilic extractives was determined by measuring the oxygen-uptake rate during the laccase-catalyzed reaction with hexane/acetone extractives obtained from wood chips. These results demonstrate that laccase treatments have great potential to alleviate extractives-related problems encountered in TWP/newsprint mills, such as the low coefficient of friction of newsprint products.