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Enzymatic Solutions to Enhance Bonding, Bleaching and Contaminant Removal,
Published online by Cambridge University Press: 15 February 2011
Abstract
Microbial enzymes can enhance the properties of virgin pulps and secondary fibers. Enzymes added to pulp slurries at key steps during fiber processing alter structure and composition of native substrates in specific ways. Lipases hydrolyze fatty acid esters thereby facilitating depitching and deinking. Cellulases remove fines and change surface properties, thereby enhancing drainage, deinking, and contaminant removal of secondary fibers. The binding domains of cellulases exfoliate or roughen the surface of cellulose fibers. This feature may be used to enhance inter-fiber bonding. Xylanases and ligninases enhance lignin and chromophore removal thereby facilitating bleaching of kraft pulps. Microbial xylanases reduce chemical demand for bleaching by 35 to 50% in softwood and hardwood pulps, respectively. Many extracellular microbial enzymes are stable at 50 to 60°C and between pH 4 and 7, and some function well at greater extremes. In some instances crude enzymes can be used, but by cloning and expressing pure enzymes at high titers more precise and economical applications can be achieved.
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- Copyright © Materials Research Society 1992
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