Exploring biobleaching possibilities of dissolving pulps by means of enzymatic treatments

Unbleached sulphite cellulose was subjected to an LQPo biobleaching sequence with the intention to elucidate the potential of LMS as an alternative to conventional bleaching processes. The enzymatic stage (L) was performed with the presence of Trametes villosa laccase and violuric acid. This enzymatic stage was followed by a chelating stage (Q) and then by a hydrogen peroxide stage reinforced with pressurized oxygen (Po). The outstanding results obtained with laccase-violuric acid system fulfil the characteristics of commercial dissolving-grade pulp (high reactivity, high ISO brightness, preserved cellulose integrity and low content of hemicellulose). Additionally, the enzymatic treatment saved 2h of reaction time and about 70% of hydrogen peroxide consumption, relative to a conventional hydrogen peroxide sequence (Po