Abstract:

Deinking technology of old newsprint (ONP) by cellulase or hemicellulase combined with laccase/mediator system (LMS) was investigated. The effective residual ink concentration (ERIC) of the deinked pulp was lower than that of the pulp deinked with each individual enzyme, which suggested that ONP could be deinked by these enzymes synergistically. Brightness after H₂O₂ bleaching and physical properties of the pulps were better than those of the pulp obtained by pulping with each individual enzyme. Fiber morphology changes during the deinking were studied by fiber average length and coarseness, specific surface area, specific volume determination and environmental scanning electronic microscopy (ESEM) observations. Comparing with the control pulp, fiber average length and coarseness of LMS-cellulase and LMS-hemicellulase synergistic deinking pulp decreased. Specific surface area and specific volume of synergistic deinked pulp fibers were higher than those of the control pulp fibers. ESEM images indicated that fibrils were present on the fiber surface after synergistic treatment.