球磨壳聚糖在氢氧化锂溶液中的吸收

Adsorption Behavior of Ball-milled Chitosan in LiOH Solution

采用行星式球磨机对壳聚糖进行球磨处理,研究了温度和氢氧化锂浓度对球磨壳聚糖在氢氧化锂溶液中吸收效果的影响,并通过傅立叶红外光谱和X-射线衍射进行表征。在球磨过程中,壳聚糖的脱乙酰度没有变化,而分子量呈逐渐减小的趋势。球磨壳聚糖在LiOH溶液中的膨胀度均高于原壳聚糖在LiOH溶液中的膨胀度,说明球磨处理可以促进壳聚糖在氢氧化锂溶液中的吸收。溶解温度和LiOH溶液的浓度对壳聚糖的膨胀度有显著影响,其中球磨壳聚糖在5℃、4.8wt%LiOH溶液中膨胀度最高,与壳聚糖溶胀于氢氧化锂溶液经冻融后的膨胀度无显著性差异,说明壳聚糖经过球磨处理后,不需要经过繁琐的冷冻-解冻过程,在低温氢氧化锂溶液中可以达到相同的溶解效果。X-射线衍射和红外图谱分析可知壳聚糖在LiOH溶液的溶胀过程中,壳聚糖的结晶结构受到破坏,壳聚糖的乙酰氨基和羟基与LiOH发生反应。

Chitosan was ball milled by a planetary ball mill, and the effects of temperature and concentration of LiOH aqueous solution on the adsorption of chitosan in LiOH aqueous solution were studied and characterized by FT-IR spectra and XPRD spectra. The deacetylation degree of chitosan had no change, while the molecular weight of chitosan gradually declined during ball milling. Swelling degree of ball-milled chitosan in LiOH aqueous solution was all higher than that of the native chitosan in LiOH aqueous solution, which illustrated that ball milling treatment could promote the absorption of chitosan in LiOH aqueous solution. The solution temperature and concentration of LiOH aqueous solution had a significant influence on the swelling degree of chitosan and the swelling degree of ball-milled chitosan at 5 ℃ in 4.8 wt% LiOH aqueous solution was the highest, which had no significant difference with swelling degree of chitosan in 4.8 wt% LiOH solution by freezing-blasting. It illustrated that adsorption of ball-milled chitosan in low-temperature LiOH aqueous solution could also achieve the same effect of dissolution without tedious process of freezing-blasting. XPRD spectra and FT-IR spectra indicated that LiOH destroyed the crystal structure of chitosan and reacted with the acetyl and the hydroxyl groups of chitosan during the swelling process of LiOH solution.