LPMO结合硫酸水解制备纤维素纳米晶体

Preparation of CNC by Combining LPMO Prehydrolysis with Sulfuric Acid Hydrolysis

关键词:  纤维素纳米晶体  裂解性多糖单加氧酶  硫酸水解  制备

Key Words:cellulose nanocrystal  lytic polysaccharide monooxy-genase  sulfuric acid hydrolysis  preparation

摘要:以棉溶解浆为原料，使用裂解性多糖单加氧酶（LPMO）预水解结合硫酸水解制备纤维素纳米晶体（CNC），对LPMO预水解前后纤维的微观形态和制得的CNC进行了粒径、结晶度和微观形态等表征，并与仅硫酸水解制备的CNC进行对比。研究发现，采用质量分数60%硫酸水解时，经LPMO预水解得到的CNC比仅硫酸水解制备的CNC平均粒径减少22 nm，结晶度提高8.8个百分点，得率提高19.3个百分点。在LPMO预水解后，随着硫酸质量分数降低，CNC的得率和羧基与磺酸基总量减少，粒径上升，而结晶度无明显正比关系。从LPMO作用整体效果来看，预水解结合50%硫酸得到的CNC与对照组相比粒径增加9 nm，羧基和磺酸基总量略小，而结晶度提高6.4个百分点，得率提高18.4个百分点，其原子力显微镜（AFM）表征显示已达到纳米水平。故通过LPMO预水解结合50%硫酸即可制得CNC，这可降低对工业生产上设备耐酸能力的要求。但LPMO反应周期长，因此在实际工业应用中有待进一步研究。

Abstract:The LPMO prehydrolysis combined with sulfuric acid hydrolysis was used to prepare cellulose nanocrystal （CNC） in this study. The micro morphology of cellulose pretreated before and after LPMO prehydrolysis was studied. The particle size， crystallinity， and micro morphology of the as-prepared CNC and the CNC prepared by only sulfuric acid hydrolysis were characterized and compared. The results showed that when the mass fraction of sulfuric acid was 60%， average particle size of the CNC pretreated by LPMO decreased by 22 nm， while the crystallinity and yield of which increased by 8.8 percentage points and 19.3 percentage points， respectively. After LPMO prehydrolysis， with the decrease of the sulfuric acid mass fraction， the yield of CNC and the total amount of carboxyl sulfonic group decreased， the particle size increased， while the crystallinity showed no correlation with it. It was found that the particle size of CNC prepared by LPMO prehydrolysis combining sulfuric acid hydrolysis （mass fraction of 50%） increased by 9 nm compared with the control group， the total amount of carboxyl sulfonic group of which was smaller， while the crystallinity and yield increased by 6.4 percentage points and 18.4 percentage points， respectively. The AFM characterization of which confirmed its nanoscale. Therefore， desirable CNC could be prepared by LPMO prehydrolysis combining 50% sulfuric acid， which would fit the using requirement of more equipment. However， the reaction period of LPMO is long， which needs to be further studied in practical industrial application.