Investigation the fiber dimensions, chemical composition and soda pulp production from sorghum straw

Cereal straws including grain sorghum varieties can be used for pulp production due to the significant amount of residual straw after harvesting. This study showed that there are no significant differences between fiber dimension and papermaking coefficients of two varieties of sorghum (Kimia and Sepideh). The average of fiber length، fiber width، lumen diameter، and cell wall thickness were measured as 1. 19 mm، 23. 20، 15. 34، and 3. 93 µm، respectively. Significant difference (P < 0. 05) was found among all chemical composition of two varieties except lignin content. The average content of holocellulose، alpha-cellulose، lignin، extractive، and ash were determined as 62. 13%، 37. 71%، 21. 05%، 9. 58% and 6. 97%، respectively. The result revealed that pulp strength produced from Sepideh variety was better. However it requires more intense delignification compared to Kimia variety. The highest screen yield (33. 19%) was reached applying the treatment combination of 170°C، 12% NaOH، and 75 minutes from the Sepideh variety. Sorghum pulp could be combined with the virgin pulp to compensate cellulose raw material shortage in paper industry.