Investigation on the Influence of the Alkaline Preextraction of Hemicelluloses on the Properties of Rice Straw Soda-AQ Pulp

The effect of partial pre-extraction of hemicelluloses on the properties of rice straw soda AQ pulp to produce valuable by products from this pre-extraction was investigated. The pre-extraction conditions were conducted using 10% sodium hydroxide (based on dry weight of the rice straw), at 50 °C for 90 minutes to reach the extraction rate of 48.1% of the hemicelluloses. Soda-AQ pulping was performed under different conditions at pre-determined pulping time and liquor to straw ratios. The optimum pulping conditions was found as 14% active alkali, 160 °C and 45 minutes pulping time. Comparasion of per-extracted materials with the normal rice straw indicated that to achieve the same kappa number and yield, the pretreated material requires less alkali and cooking time. The results showed that pre-extraction marginally reduced the tensile strength index of the pulp which the difference was not statistically significant with control pulping condition. However, the burst strength index of pre-extracted pulp and control was identical. The overall mechanical properties of pretreated pulp were the same as the control.