lignin dissolution at pulping process of wheat straw

The lignin dissolution in Kraft pulping for wheat straw was studied. Kraft pulping was carried out under the conditions: chemical charge of 18% (as NaOH, based on o.d. bagasse), sulfidity of 25% and liquor to wheat straw ratio of 10:1. Six cooking maximum temperatures of 85,100,110,120,130 and 150 ◦C, were selected and reaction time varied from 0 to 250 min., based on maximum temperature. The Klason lignin, acid soluble lignin, ash and extractive contents of wheat straw were 18.4%, 2.07%, 3.24% and 4.56% respectively. During alkaline pulping of wheat straw, 64% and 52% of lignin was removed before reaching to the temperature 100 ◦C and 85 respectively. The values for pulp and carbohydrates yield were, about 64%, 58% for 85 ◦C and 61%, 57% for 100◦C.