香蕉假茎多元醇液化过程中纤维素的性能表征

Characterization of cellulose from banana pseudo-stem by polyhydric alcohols liquefaction

在硫酸催化剂作用下对香蕉假茎进行聚醚多元醇液化,液化温度为150℃,采用单因素分析和正交试验方法研究液固比、时间、催化剂用量对残渣中纤维素含量的影响,采用FT-IR,TG和X射线衍射分析香蕉假茎、残渣及香蕉假茎纤维素。结果表明,残渣中纤维素含量在液化过程中随液固比的增大、时间的延长以及催化剂用量的增加先上升后下降;正交试验确定的最佳液化工艺为液固比12∶1、液化时间60 min、催化剂用量2.5mmol/g(催化剂摩尔数/香蕉假茎质量),残渣中纤维素含量为65.37%;残渣与原料的红外相比,木质素特征吸收峰基本消失;X射线衍射分析得到残渣和纤维素的结晶度分别为51.96%和62.37%,高于原料结晶度的44.83%;同时TGA表明,残渣与纤维素的热稳定性高于原料,即纤维素含量的增加提高了残渣的热稳定性,SEM显示在香蕉假茎表面有明显的降解反应发生。

A liquefaction of banana pseudo-stem in polyhydric alcohols using sulfuric acid as catalyst at 150 ℃ was developed. The liquefaction times, liquid-solid ratios, amounts of catalyst which affected contents of cellulose in liquefied banana pseudo-stem were evaluated by using single factor experiments and the orthogonal experiments. Banana pseudo-stem, liquefied banana pseudo-stem and cellulose were analyzed by FT-IR, TG and X-ray diffraction. Results show that the contents of cellulose in liquefied banana pseudo-stem were first enhanced with the increases of liquid-solid ratio, liquefaction time and amount of catalyst, then decreased. The best conditions are 12：1 （liquid-solid ratio）,60 min （liquefaction time） and 2.5 mmol/g （amount of sulfuric acid）; proportion of cellulose in liquefied banana pseudo-stem was 65.37% under these conditions. The FT-IR spectrum of the liquefied banana pseudo-stem indicates the absorption peaks of lignin disappeared compared to the raw material. The crystallinities of the liquefied banana pseudo-stem and cellulose analyzed by X-ray diffraction are 51.96% and 62.37% respectively; these are higher than that of banana pseudo-stem （44.83%）. Results of TGA suggest the thermal stabilities of liquefied banana pseudo-stem and cellulose are higher than that of banana pseudo-stem, indicating that the thermal stability is enhanced as the cellulose content increases. SEMs indicates degradation reactions take place in the surface of banana pseudo-stem.