Influence of poplar green liquor pretreatment on pentosan extraction

Green liquor pretreatment used in poplar Kraft pulping process and the influences of pretreatment conditions on pentosan extraction have been studied in this paper. The result showed that the influence of green liquor dosage (GLD) on pentosan extraction was the most remarkable, with the influence of temperature taking the second place and the influence of time the third. Under the conditions of liquor ratio 1:4, green liquor dosage 1.5L/kg (based on oven dried raw material), pretreatment 100°C, 90mins, higher pentosan extraction content was achieved, which was about 13.81%(based on the pentosan content of oven dried material). Under the best conditions of pentosan extraction, the wood after pretreatment was pulped under normal KP conditions. Comparing two kinds of pulp with and without pretreatment by green liquor at similar stock yield level, the results showed that the former had a little lower viscosity, significantly decreased Kappa number and excellent paper physical properties.