羧甲基蔗渣木聚糖的合成与表征

以蔗渣木聚糖和一氯乙酸为主要原料,乙醇水溶液为溶剂,冠醚为催化剂,经碱活化、醚化反应两步合成了羧甲基蔗渣木聚糖。考察了物料摩尔比、反应时间、反应温度和溶剂中水含量等因素对合成工艺的影响,确定的较佳工艺条件:n(蔗渣木聚糖结构单元)∶n(氢氧化钠)∶n(一氯乙酸)=1∶3.25∶1.25,溶剂V(乙醇)∶V(水)=4∶1,45℃碱化2 h,70℃醚化3 h,所得羧甲基化产物的取代度可达0.59。用FTIR与SEM对原料和产物的结构进行了表征。热分析表明,反应后蔗渣木聚糖在234~312℃内分解量由总质量的46.27%降至30.58%。质量浓度为12 g/L的产物水溶液的表面张力为63.6 mN/m。

Synthesis and Characterization of Carboxymethyl Bagasse Xylan

Carboxymethyl bagasse xylan was synthesized from alkalization and etherification of bagasse xylan with crown ether as catalyst,using bagasse xylan and chloroacetic acid as the main feedstock.The optimal process condition was obtained as follows:n(structural unit of bagasse xylan):n(sodium hydroxide):n(chloroacetic acid)=1:3.25:1.25,with solvent V(ethanol):V(water)=4:1,quaternization temperature 45 ℃ and reaction time 2 hours,etherification reaction temperature 70 ℃ and reaction time 3 hours.The DS of carboxymethyl bagasse xylan was obtained as 0.59.The structures of raw material and the product were characterized by FTIR and SEM. The TG data indicated that thermal decomposition of the bagasse xylan decreased to 30.58% of the total mass from 46.27% after carboxymethylation in the temperature range of 234～312 ℃.The surface tension of the product was 63.6 mN/m at the mass concentration of 1.2 g/L.