Moving Toward a Sustainable Future
Wall, Thomas A.
Levit, Mikhail V.
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The Moving Toward a Sustainable Future panel presented research on such sustainability topics from climate change to saving trees by making paper from grains.Levit: A new approach to pulping agricultural residue is presented where wood chips are pulped together with wheat straw and corn stover in one digester. The availability and cost of virgin fiber are often limiting the mill’s productivity hence utilization of compatible agricultural residue may at least partially solve the problem as well as establish new products with modified and improved properties. This study employs annual crop residues as biorenewable resources that can be substituted for 10, 15 and 20 % of woodchips without special changes in pulping conditions. The benefit of using agricultural residues is their low cost and wide availability. Slightly higher yields and increase in Kappa number are observed for brownstock while mechanical properties of handsheets are improved significantly. Bleaching of pulps made from blends containing agricultural residue and hardwood chips was also investigated by applying a relatively mild sequence to achieve target brightness ISO 89. Overall a maximum increase in tensile index was 29% and 12% in tear index for unrefined samples containing wheat straw in comparison to hardwood-only control sample. Viscosities of pulps and carbohydrate profiles were traced throughout the pulping and bleaching process and black liquor analysis was performed. Physical properties development is attributed to higher levels of xylan that is introduced with agricultural fiber and an attempt is made to correlate xylan content to the strength of handsheets.