Upgrading the qualitative characteristics of mixed recycled ONP and OMG pulps with hemicellulase

Enzymatic deinking has been suggested as an environmentally friendly alternative to complement and replace for conventional chemical deinking. In the present research, the effect of hemicellulase from Aspergillus niger has been evaluated on paper quality of mixed 70% old newspaper (ONP) and 30% old magazine (OMG) pulp. Hemicellulose was used at different charges of 0.1 (H1), 0.2 (H2), 0.5 (H3) and 1 (H4) percentages based on oven dry weight of pulp and different times of 40 (T1), 50 (T2), and (T3) under constant conditions of %10 consistency, temperature 55-60 °C at pH range of 6.5-7 and then the pulps were washed and floated. The results showed that compared to undeinked pulp (C1) and chemical deinked pulp (C2), papers with higher brightness, whiteness and appropriate opacity could be achieved at % 0.2 enzyme concentration and duration time of 60 min (H2T3) and also % 0.5 enzyme concentration and duration time of 50 min (H3T2). Also, the results of assessments indicate that the highest tensile index (32.271 and 30.017 Nm/g), breaking length (3.131 and 2.974 km) and stiffness (3.94 and 4.12 mN) were observed in treatments of H2T3 and H3T3, and the highest tear index (7.688 and 7.34 mN.m2/g) was observed in treatments of H1T1 andH1T2 respectively. These results are more desirable than paper produced with treatment samples of C1 and C2. In general, achieved results from this research indicate that hemicellulase has a good potential to improve the quality of mixed recycled ONP and OMG waste papers vs. standard conventional system.