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Pre-extraction of Hemicelluloses from Poplar Chips and its Effect on Kraft Pulping
Jiachuan Chen,Tingpeng Jia,Guihua Yang,Ming He 한국펄프·종이공학회 2017 펄프.종이技術 Vol.49 No.2
Hemicelluloses are useful materials for papermaking and other biotechnological applications. Based on the concept of transformation of a chemical pulp mill into an integrated forest biorefinery, hemicelluloses are partially extracted or separated, and the remained substrate (mainly cellulose and lignin) can be further delignified for pulp. In the present work, the parameters of pre-extraction or the effect on pulp properties was investigated. The hot-water extraction and alkaline extraction prior to kraft pulping of poplar were carried out in order to partially extract hemicelluloses. It was found that the hot water extraction can obtain a mass loss of 7.72% at 140℃ for 60 min with a water-to-wood ratio of 6:1, and mass loss of woodchips increased with extraction time and temperature. While in the alkaline extraction, mass loss of woodchips reached 15.20% at 170℃ for 120 min with 3% dosage of NaOH. The concentrations of sugars depolymerized from hemicellulose in extraction liquor increased with the increase of extraction time and temperature. The residual woodchips were subjected to kraft pulping at 165℃ for 60 min with 20% effective alkali, 25% sulfidity and a liquor-to-wood ratio of 4:1. Considering the needs for resulting pulp properties, a temperature of 140℃ and a pre-extraction time of 60 min without NaOH addition were recommended as the optimum pre-extraction in this experiment.