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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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
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