Influence of pulping conditions on eucalyptus kraft pulp yield, quality, and bleachability.Application: These findings may allow mills to adjust their pulping process conditions for improved pulp yields or to improve pulp bleachability, according to according to prep. 1. As stated or indicated by; on the authority of: according to historians. 2. In keeping with: according to instructions. 3. their needs and desire. ********** This study evaluates the effect of cooking residual alkali and temperature on kraft pulp yield, bleachability, and quality. We cooked Eucalyptus grandis Eucalyptus grandis, Flooded gum, Rose gum, is a medium to tall tree with smooth bark, rough at the base fibrous or flaky, grey to grey-brown. Leaves are stalked, lanceolate to broad lanceolate, discolorous, to 15 x 3 cm, glossy dark green. chips at 170[degrees]C and 160[degrees]C to kappa number The Kappa number is an indication of the lignin content or bleachability of pulp. It measures the amount of bleach required during digestion of a wood pulp (part of the process of paper making) in order to obtain a pulp with agiven degree of whiteness. 16-17 using high/low residual alkali (14-18 and 3-4 g/L). We determined process yield and pulp quality by measuring strength properties, carbohydrate composition, hexenuronic acid content, alkali-leachable lignin lignin (lĭg`nĭn), a highly polymerized and complex chemical compound especially common in woody plants. The cellulose walls of the wood become impregnated with lignin, a process called lignification, which greatly increases the strength and content, and residual lignin nature. We oxygen delignified the pulps, bleached them to full brightness with the sequences D(EOP EOP Educational Opportunity Program (California State University) EOP Executive Office of the President EOP Equity Office Properties Trust (ticker) EOP Emergency Operations Plan EOP Earth Orientation Parameters )DD and D(EOP)(ZE)D, and determined their bleachability and brightness stability. The highest screened yield (54.2%) and viscosity (64.6 mPa.s) were achieved using low temperature and low residual alkali during pulping. Pulps cooked at low residual alkali showed about 1.7%-2.1% higher yield, 20%-30% higher viscosity, and higher strength properties (except for tear index) than those cooked at high residual alkali. Lower temperature and/or residual alkali during pulping favored pulp refining. Pulps produced at high residual alkali showed slightly lower oxygen delignification efficiency (2%-3%) but significantly higher (10%-15%) bleachability, regardless of cooking temperature. We found that cooking hardwoods at high temperature and white liquor alkalinity al·ka·lin·i·ty n. The alkali concentration or alkaline quality of a substance that contains alkali. alkalinity 1. the quality of being alkaline. 2. reduces pulp yield, viscosity, and beatability. However; it has the potential of increasing digester di·gest·er n. 1. One that makes a digest. 2. Chemistry A vessel in which substances are softened or decomposed, usually for further processing. Noun 1. throughput and pulp bleachability. The gains in pulp bleachability are not sufficient to economically justify the significant yield losses associated with such practice. High alkali and temperature conditions are justified only when digester throughput is the mill bottleneck. Colodette and Gomide are professors at the Federal University of Vicosa, Brazil; Russell Girard is application engineer at Praxair Inc., St. Laurent, QC, Canada, Jaaskelainen and Argyropoulos are with McGill University/Paprican, Montreal, QC, Canada. Contact Colodette by email at colodett@mail.ufv.br. |
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