Effects of washing method on the bagasse pulping characteristics by Sulfur Dioxide- Ethanol-Water (SEW) process

SO2-ethanol-water (SEW) pulping can be considered a hybrid between solvent and acid sulfite pulping processes. Recently this process in order to separation the principal components (cellulose, hemicelluloses and lignin) have been considered. The main objective of this study was to investigate the effects of washing method on the bagasse pulping characteristics by acidic fractionation of Sulfur Dioxide- Ethanol-Water (SEW). Variables included two washing pulp methods (water and 40 v/v% ethanol-water solutions), pulping duration (30-100 min.), and temperature (120 and 135 OC). Then, pulps were washed twice with 40% v/v ethanol-water at 60°C (L: W 2 L kg-1) and with deionized water at room temperature (L: W 20 L kg-1). The results showed that the final yield pulp due to lignin greater solubility in 40 v/v % ethanol-water compared to conventional systems (washing by water) decreased that the diminishing returns are statistically significant at the 1% level. Pulping result at 120 and 135 °C at different time period showed that increase in the pulping duration, kappa number is reduced.