Mea pulping - a new alternative for pulping of annual plants
2010
Hedjazi, Sahab | Kordsachia, Othar | Patt, Rudolf | Adli, Amirhossein Heidari
Pulping of wheat and rice straw with MEA as the main delignifying agent was investigated in comparison to conventional soda and soda/AQ pulping as references. In pulping of both raw materials the main focus was laid on reduction of the MEA charge by partial substitution with water. In the case of wheat straw pulping more than 50% of MEA can be replaced by water without seriously retarding lignin removal. The loss in delignification efficiency can be fully compensated by adding anthraquinone (AQ), which is a powerful catalyst also in MEA pulping of wheat straw. Rice straw can be even more effectively delignified with MEA as wheat straw. At a maximum cooking temperature of 150 degrees C, a sufficient delignification was achieved for both raw materials. - The pulps obtained in the MEA/water cooks were selected for bleaching. Both, O/Q/OP/DQ/P ("ECF light") and O/Q/OP/ZQ/P (TCFZ) bleaching were applied in the case of wheat straw. A brightness of 80% ISO was reached at a kappa number below 3. In the case of rice straw, ECF bleaching (DEpD) was applied. A similar brightness of 80% ISO was reached at a kappa number below 2.
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