ORGANOSOLV PULPING OF WHEAT STRAW BY GLYCEROL

Pulping of wheat straw was studied with an organic solvent (glycerol) and 2% NaOH as a catalyst, and without catalyst, at various cooking times (180, 90, 45 and 30 min), and at reflux temperature (195-205 degrees C) as cooking temperature, to investigate the properties of the obtained pulp (cooking yield, kappa number, freeness (CSF), fiber length, a-cellulose, gamma-cellulose, ash) and paper (breaking length, burst index, fold endurance, tear index). The best properties of the handsheets were obtained with 2% sodium hydroxide in the cooking solvent, at 30 min as cooking time. As a result of using the processing variables over the variation ranges considered, the following optimum values of the dependent variables were obtained: 64.1% (yield), 64 (kappa number), 300 mL CSF (freeness), 11.89 km (breaking length), 60.38 (folding endurance), 9.27 mNm(2)g(-1) (tear index) and 4.60 kNg(-1) (burst index) for pulps and handsheets. The results obtained showed that, under the cooking conditions applied, either including the use of a catalyst or not, delignification increased by increasing the cooking time, although the brightness of the handsheets was reduced. These results involved a secondary reaction between the organic solvent glycerol and the micro-fragments of fibers during cooking.