Separation Of Three Components Of Lignocellulose And Preparation Of Carbon Nanotubes

In this paper,deep eutectic solvent(DES)are used to separate the three components of lignocellulose,and each component is used to prepare carbon nanotubes(CNTs).Finally,the obtained CNTs are used to immobilize lipase.Through the experiment,select 1.0 wt%dilute sulfuric acid and react at 120? for 1h as the best reaction condition for dilute acid hydrolysis to remove hemicellulose.At this time,the hemicellulose removal rate can reach more than 90%,and the solid recovery rate can also be maintained at more than 80%.Under different conditions,the relationship between cellulose recovery rate,hemicellulose recovery rate and lignin removal rate of dilute acid treated and non-dilute acid treated Pennisetum and Poplar was compared.It was found that the lignin extraction rate of the samples treated with dilute acid was reduced by about 10%,but the cellulose recovery rate was increased,and the recovery rate of hemicellulose was significantly reduced.Compared with the lignin extraction rate reduced by 10%(also reached more than 70%),the change in cellulose and hemicellulose recovery rate is obviously more advantageous.After being treated with dilute acid and DES,the molecular weight and structure of the lignin products obtained from Pennisetum and Poplar were analyzed.It can be seen that the molecular weight of the products is small,the molecular weight distribution is relatively uniform,the basic active functional group is maintained,and the lignin skeleton structure characteristics closest to the natural lignin are maintained.These basic data are of great significance for the subsequent development and utilization of DES.In the experiment,the catalyst loading and reaction temperature were used as the factors of investigation.By comparing the morphology of CNTs prepared by catalytic cracking under different conditions,10.0 wt%catalyst loading was selected,400? as the low temperature stage,and 850? as the high temperature stage.The products prepared from different raw materials are quite different,among which only raw material and cellulose can get CNTs by this method,which shows that cellulose is the main component of CNTs in this experimental method.Because of its large molecular weight and complex molecular structure,lignin can not meet the requirements of CNTs prepared from lignin under the existing experimental conditions.How to use lignin to prepare CNTs still needs further experimental exploration.After comparison,it was found that the adsorption of Amano lipase from Pseudomonas fluorescens on the self-made CNTs and the purchased MWNTs was similar to the hydrolase activity.Therefore,it was also considered that the CNTs prepared in the laboratory had similar performance to those sold on the market.The esterification rate increased from about 15%to 99%of the free enzyme,and the esterification rate decreased to about 50%after six times of recycling,which was still much higher than that of the free enzyme,indicating that the activity and stability of lipase after immobilization were greatly improved.