氢氧化钠预处理对乳酸-氯化胆碱处理化学木浆中半纤维素选择性溶出的影响  

Effect of Sodium Hydroxide Pretreatment on the Selective Dissolution of Hemicellulose from Chemical Wood Pulp Treated by Lactic Acid-Choline Chloride

作　　者：汪心娉 赵鸿辉 兰金鑫 林嫦妹 倪柳芳 曹石林[1] 马晓娟[1] Wang Xinping;Zhao Honghui;Lan Jinxin;Lin Changmei;Ni Liufang;Cao Shilin;Ma Xiaojuan(Fujian Agriculture and Forestry University,Fuzhou 350108,P.R.China;Fujian University of Technology)

机构地区：[1]福建农林大学,福州350108 [2]福建工程学院

出　　处：《东北林业大学学报》2023年第2期133-137,共5页Journal of Northeast Forestry University

基　　金：福建省科技厅高校产学合作项目(2020H6008、2021H6005)。

摘　　要：以山东华泰纸业股份有限公司提供的桉木化学浆为试验材料,以氢氧化钠(NaOH)溶液、乳酸(LA)、氯化胆碱(ChCl)为主要试剂,按照摩尔比(n(乳酸)∶n(氯化胆碱))为1∶1的比例制备乳酸-氯化胆碱低共熔溶剂;用质量分数为5%的氢氧化钠溶液对纸浆纤维进行预处理,然后用制备的乳酸-氯化胆碱低共熔溶剂对预处理后的纸浆进行二次处理,获得试验浆料样品(化学浆);参照国家标准测定并计算试验浆料样品半纤维素去除率、纤维素损失率、半纤维素选择性、纤维素结晶度、纤维素特性黏度,分析氢氧化钠预处理在乳酸-氯化胆碱处理桉木化学浆过程中的效果及机理。结果表明:氢氧化钠预处理,不仅可以提高乳酸-氯化胆碱低共熔溶剂处理桉木化学浆过程中半纤维素的选择性溶出,而且能减少纤维素的降解。与乳酸-氯化胆碱低共熔溶剂单段处理相比,“氢氧化钠+(乳酸-氯化胆碱)”处理后,化学浆中半纤维素的去除率从29.3%提高到57.0%、浆料特性黏度从448 g·L^(-1)提高到844 g·L^(-1)、纤维素结晶度从79.6%提高到80.7%。氢氧化钠对浆料的润胀,减小了纤维素与半纤维素及纤维素分子间氢键的结合力;促进乳酸-氯化胆碱进入纤维内部,与半纤维素或纤维素羟基作用,加强了半纤维素溶出。此外,碱的残余,对乳酸-氯化胆碱中的酸有一定的中和作用,减少了纤维素在乳酸-氯化胆碱中的酸性降解。The chemical pulp of eucalyptus from Shandong Huatai Paper Co.,Ltd.was used as the test material,NaOH,lactic acid(LA)and choline chloride(ChCl)were used as the main reagents.The DES(lactic acid-choline chloride)was prepared according to the molar ratio(n(lactic acid)∶n(choline chloride))ratio of 1∶1.The chemical pulp was sequential treated by(activated)5%sodium hydroxide solution and lactic acid-choline chloride deep eutectic solvent.The hemicellulose removal rate,cellulose loss rate,hemicellulose selectivity,cellulose crystallinity and cellulose intrinsic viscosity of the treated pulp samples were measured and calculated according to the national standards.The effect and mechanism of sodium hydroxide pretreatment on the process of lactic acid-choline chloride treatment of eucalyptus chemical pulp were analyzed.The results show that NaOH pretreatment can not only improve the selective dissolution of hemicellulose in LA/ChCl process,but also reduce the degradation of cellulose.Compared with LA/ChCl,NaOH-LA/ChCl can improve the selective dissolution of hemicellulose in chemical pulp.The removal rate of hemicellulose increased from 29.3%to 57.0%,the intrinsic viscosity of plup increased from 448 to 844 mg·mL^(-1),and the crystallinity of cellulose increased from 79.6%to 80.7%.NaOH swelling of the pulp reduced the binding force between the cellulose and hemicellulose and cellulose molecules and promoted LA/ChCl to enter the fiber and interact with hemicellulose or cellulose hydroxyl,thereby enhancing hemicellulose dissolution.In addition,the residue of alkali can neutralize the acid in LA/ChCl and reduce the acid degradation of cellulose in LA/ChCl.

关 键 词：桉木 木浆 低共熔溶剂 氢氧化钠预处理 纤维素 半纤维素 

分 类 号：TS721[轻工技术与工程—制浆造纸工程] TS743