Determination of Organosolv Pulping Condition of Wheat (Triticum aestium L.) straw

SUMMARY There are several studies on novel pulping methods which would alleviate the enviromental problems and profitable results with smaller-mill size and economically more viable than conventional pulping methods. "Organosolv" pulping processes based on the use of organic solvents as delignification agent instead of inorganic reactives used in conventional pulping processes were brought a different aproach to pulp industry. This study was aimed possibility of organosolv pulping of the wheat straw which is known as an important raw-material for pulp production in Türkiye. To obtain optimum pulping conditions, ethanol ratio, cooking time and temperature for pulping liquor were changed systematically and 18 pulping trial were made. Obtained result showed that the pulping temperature at 170 °C was critical for delignification and fiber liberation. Under this limit, sufficient delignification and chemical defiberation were not observed. However, fast fiber liberation accured by applying 180-190 °C pulping temperatures. But increasing of pulping time at high temperature level,caused serious viscosity and strength lacks. As a result, optimum pulp properties obtained at 170 °C and at 120 min. cooking time with 50 % aqueous alcohol. Organosolv wheat straw pulp obtained optimum pulping conditions has 48 % screened yield, 43 kappa number, 849 cm3/g viscosity, 5.7 km breaking length, IJ /J 2.1 kPa.m" /g. burst index, 6.7 mN.m" /g tear index and 17 elrepho brightness. Consequently, wheat straw organosolv pulp showed high values of yield and viscosity, and equal strength properties at the same kappa level compared with the soda- oxygen, lime-soda-oxygen and soda-air straw pulps. However, brightness value of organosolv pulps was found significantly low. Key Words: Wheat straw, organosolv pulping, delignification, strength properties, ethanol- water pulping. IX