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Abstract
This research studied the effects of cellulase and laccase in flotation deinking of old newsprint. The
cellulase was produced from Aspergillus niger while the laccase was produced from white rot fungus Pycnoporus
sanguineus which was isolated in Thailand. To examine the effects of these enzymes in flotation efficiency, the
cellulase and laccase were individually and separately employed with the dosage of 0.2% based on O.D. (oven
dried) pulp weight. Then, the use of cellulase together with laccase with the dosage of 0.1% each and 0.2% each
based on O.D. pulp weight was also investigated, respectively. It was found that all cases of enzymes did not
impact on pulp yield. In addition, using enzymes in flotation deinking provided higher brightness, lower ERIC
(effective residual ink concentration), longer fiber length, lower fines content, higher tensile index, higher burst
index and higher tear index than the control case (the experiment without enzyme). The use of cellulase together
with laccase with the dosage of 0.2% each provided the best deinking results as indicated by highest brightness,
lowest ERIC, longest fiber length, lowest fines content, highest freeness and highest paper strength. These results
were better than the case of using cellulase alone, the case of using cellulase together with laccase with the dosage
of 0.1% each and the case of using laccase alone, respectively.
Keywords: Flotation deinking, Cellulase, Laccase, Newsprint
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