Development Of An Enzymatic Deinking System Of Laser Printed Waste Papers
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Date
2005-06
Authors
Lee, Chee Keong
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Abstract
The present work deal with the development of the enzymatic deinking process of waste
papers. Based on the enzymatic deinking of laser-printed waste papers, studies on the
optimization of enzymatic hydrolysis and ink removal were performed using
commercial enzyme preparations. The optimum activities and stabilities at different pH
and temperatures of the enzymes, cellulase A "Amano"3 (C), hemicellulase "Amano"90
(H) and lipase F-AP 15 (L) were selected for use in deinking process. The optimum
temperature and pH of C, Hand L were 55°C and pH 2.5, 50°C and pH 4.5, 40°C and
pH 7.5, respectively. The use of CH sequentially resulted in highest deinking efficiency
(61.7%). Scanning electron micrograph revealed that the enzymatic hydrolysis on paper
resulted the toner been ripped off from the paper, which was mainly carried out by
enzyme cellulase and hemicellulase. Pulping at 1 % consistency for 1 min demonstrated
highest deinking efficiency (66.2%). Pre-treatment of paper with 0.25 M HCI followed
by enzymatic hydrolysis ( at 50°C, pH 3.5, with no agitation, with the pulp
concentration of 4% (w/v), 2.5 U of enzymes per gram of air dry weight pulp at C:H
ratio of 1: 1 and 60 min hydrolysis time) resulted the maximum deinking efficiency of
68.6%. Ink removal under optimum .flotation process (pH 6.0, 0.5 % (w/w) of Tween
80, 10 Llmin of air flow rate, 35°C and 15 min of flotation time) resulted highest
deinking efficiency (86.6%). Effect of enzymatic deinking on different type of waste
paper studied revealed that the highest deinking efficiency of 86.6% was detected on
laser-printed paper but the lowest deinking efficiency of 12.9% was obtained by
newspaper. All enzymatic treatments of waste papers significant influence drainage rate
and physical properties of the de-inked paper. Enzymatic treatment resulted "highest
drainage rate of 103.7 Llmin with the laser-printed papers. Enzymatic deinking resulted
2.3% increment in tensile index with magazine paper but 3.0% decreased with laser-
printed paper. Enzymatic hydrolysis caused 21.1 % reduction in tear index relative to the
blank for bubble jet printed paper. On the other hand, 3.1 % improved in tear index was
observed for laser printed paper. The study on the burst strength revealed that enzymatic
hydrolysis resulted 4.7% increased in burst index compared to the blank for laserprinted
paper. Meanwhile, photocopy paper showed the highest reduction in burst index,
which was 8.3%. The results obtained in this work suggested that enzymatic deinking
can be a potential alternative to the chemical method in the recycling of waste papers.
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Keywords
Development Of An Enzymatic Deinking System , Of Laser Printed Waste Papers