Wheat Straw Pre-Extraction with Hot Water and the Recovered Pulping Liquor and Its Effects on Pulping and Paper Properties

Hemicellulose pre-extraction and recovering before pulping process is an approach for supplying the sugar feedstock used in production of fuels and chemicals. Wheat straw hot water pre-extraction for reaching to 10 % weight loss was carried out in the present study. Pre-extracted liquor from each stage was used as a media for subsequent extraction stage (three stages) in pre-extraction process. The results showed that soda-AQ pulping of pre-extracted straw is performed at less severe conditions i.e. shorter time and lower temperature as compared to non-pre-extracted straw. The pulping yield of pre-treated straw was higher than control pulp; however, the total pulp yield (based on oven dried weight of raw straw) was lower in the pre-extracted samples. Due to lack of hemicelluloses, pre-extracted pulps showed a weaker response to refining and the produced handsheets had lower tear index and air resistant than handsheets made of non pre-extracted pulp, while no significant difference was noticed in burst and tensile indices of handsheets produced from extracted and non-extracted pulp samples.