Production of reprocessed paper from old newsprint by using modified cellulase

Cellulase was modified with copolymer of polyethylene oxide and maleic acid anhydride by maleylation reaction, and modified cellulase was applied in the reprocessing of old newsprint (ONP). Cellulase of modified cellulase enhanced the detachment of ink particles by fiber fibrillation. The copolymer, which acted as a suffactant, formed bubbles and removed the ink particles in the floatation process. Modified cellulase showed the same deinking ability without excess dosage compared with the conventional method. Also, it improved the physical properties such as tensile strength, brightness, and whiteness, compared with the conventional deinking process. The bond between the ink and fiber got stronger as the storage time increased, and it became very difficult to remove. Yet, modified cellulase increased the deinking ability by 41% compared with the conventional process, for a 11-month storage time. It removed yellowing and increased whiteness and brightness by 15.7% and 1.9%, respectively. Modified cellulase also enhanced the fiber fibrillation for better tensile strength by 4.0%.