Applications of Enzymes in Paper Deinking Processes

Abstract

Enzymes can be applied for the deinking of wastepaper for the recovery of secondary fibers. Mainly cellulases and hemicellulases have been utilized for the deinking of different types of newsprint and office waste papers. Ink removal efficiencies and brightness gains have been reported in several cases to be equal or superior to conventional chemical deinking procedures. Paper printed with vegetable oil based inks could be deinked efficiently in a deinking procedure including a neutral deinking chemical in combination with lipase, cellulase and xylanase. Treatment with lipase resulted in a higher decrease of residual ink area and dirt count compared to treatments with a combination of the enzymes which gave the highest increase in brightness of the deinked paper.Worldwide, paper production has increased over the last ten years by 4% annually and is projected to further increase by 2% per year until year 2000 to about 300 million tons. Recycled paper will by then contribute more than 40% of the raw material supply for paper making while in the U.S., Japan and Germany, the recovery rates are expected to be well above 50%. Utilization of the secondary fiber from recycled paper requires effective removal of impurities including the printing inks in a deinking process. The printing inks are removed from the fibers using chemical and mechanical treatment to displace ink particles from the surface of the fibers. Conventional deinking chemicals can have a negative impact on both the environment and the quality of the recycled paper. On the other hand, treatments with enzymes have been shown to be effective in assisting or replacing the chemical deinking processes in addition to improving paper quality such as strength and dewatering properties (/). The ease with which the ink can be removed from the fibers is influenced by the type of inks and drying method used, the printing process and the age of the paper.The ecological and qualitative demands on ink products have resulted in a continuous development of more environmentally friendly products. Inks based on vegetable oils (VOI) represent such advanced products, since they reduce VOC (volatile

Do Enzymatic Hydrolyzability and Simons' Stain Reflect the Changes in the Accessibility of Lignocellulosic Substrates to Cellulase Enzymes?

“…Applications of enzymes in the bioprocessing of lignocellulosics include hydrolysis of cellulose to glucose by cellulases (1); de‐inking of secondary fibers by cellulases, xylanases, esterases, and/or lipases (2, 3); and the enzymatic treatment of recycled paper to restore fiber swelling, flexibility, and mechanical strength, which had been reduced by drying and recycling during the papermaking operations (2−5). It has also been shown that combinations of fungal enzyme treatments and physical refining can provide a means for using coarse wood fibers (e.g., Douglas fir) to produce finer paper products (6).…”

Physicochemical characterization of cellulase produced from <i>Kurthia gibsonii</i> isolated from cassava dumpsites in Ibadan, Nigeria

“…Cellulase has attracted many scientific and industrial attention for its applications in many fields such as animal feed, textile, pulp and paper industries, ethanol production, laundry (Voragen, 1992;Godfrey and West, 1996;Tolan and Foody, 1999); de-inking of recycled paper (Smook, 1992;Moekerbak and Zimmermann, 1998). The importance of cellulase and allied enzymes is increasing in the global market.…”