Investigation on the Application of Buffered Sulfite Semichemical Process for Pulp Production from Corn Stalks

Buffered sulfite pulping of corn stalks was investigated. Four variables including sodium hydroxide charge at 12، 14، and 16%، sodium carbonate charge at 4 and 8%، pulping temperature at 145 and 165°C and pulping time of 15 and 30 minutes were evaluated. Results showed that increasing any of the four variables reduced both total yield and kappa number where the influence of pulping temperature was more pronounced. The highest total yield and accepted yield were measured to be 59. 7% and 51. 4%، respectively، applying pulping condition of 12% Na2SO3، 4% Na2CO3، 145°C and 15 minutes. The kappa number was 55. 4. The lowest total yield of 34. 1% and kappa number of 16 were achieved using 16% Na2SO3، 8% Na2CO3، 165°C and 30 minutes. Two pulps with the highest total yield and one with the lowest kappa number were selected for further evaluation. The tensile index of selected pulps varied between 52. 5 and 66. 6 Nm/g، and the relevant value for low yield pulp was 62. 9 N. m/g. Tear index varied between 5. 2 and 6. 7 mN. m2/g and the respective value for low yield pulp was 7. 3 mN. m2/g. The brightness values of the high yield pulps were measured to be 26 and 27% ISO، respectively and 40% for the low yield pulp. The results of this study revealed that brown pulp can be produced using corn stalks.