Study On Extraction Of Cellulose From Rabdosia Rubescens Residue And Preparation Of Functional Cellulose Membrane

Rabdosia rubescens is an important Chinese herbal medicine in China.At present,it is mainly extracted with water-alcohol to prepare medicinal extract.Usually,1 Kg of hay can obtain 0.1-0.12 Kg of extract,but more than 80%of the total extraction residue becomes solid waste,causing a weast of resources.Therefore,how to effectively utilize rubescens residue is urged to be solved.With the decrease of non-renewable resources such as oil,cellulose,the most abundant renewable resources in the world,has become a hot research field.Studies have shown that rubescens residue is rich in cellulose.If it is utilized,it can not only find new materials for cellulose,but also solve the waste of rubescens residue.Therefore,this paper studied the application of rubescens cellulose as the raw material of membrane materials,and carried out a series of characterization and performance tests on membrance material.The research results are as follows:1.According to Chinese standars,the composition of the residue of Rubescens was analyzed.The study shows that the cellulose content was 40.46%,polypentose3.98%,pectin content 1.38%,acid-insoluble lingnin content was 25.0%,acid-soluble lignin was 1.79%.The Na OH-AQ method was used to extract cellulose,and single factor optimization combined with the corresponding surface,The results showed that the cellulose extraction rate was 97.07%when Na OH(wt%)=33.0%,the liquid:material=7.5:1(m L/g),T=150?.Analyzing the extracted cellulose on a fiber qualityanalyzer,it was found that the quality was good,which could be used as cellulose raw material.2.Cellulose Membrane was prepared by phase conversion method with NMMO solution.Observation through a microscope revealed that the cellulose was completely dissolved after 180 min.The membrane-forming properties of cellulose were studied by a digital rotational viscometer,and it was found that when the cellulose content is 5%-8%,when the temperature of the casting liquid is higher than70?,the membrane-forming properties were good.Fourier infrared spectroscopy(FTIR)and X-ray diffractometer(XRD)indicate that cellulose dissolution is a physical process.The crystalline structure of cellulose changes from type?to type?.The crystallinity decreases but the structure does not change.The thermogravimetric(TG)results show that the thermal stability of cellulose film decreased,and Scanning electron microscope(SEM)results show that 5%cellulose film was compact and smooth,The hydrophobicity increases with the increase of the content of vitamin in the casting soluution.The mechanical properties of cellulose membrane,the rejection rate and water flux were positively correlated with content of cellulose.3.Microcrystalline cellulose(MCC)was prepared by acid hydrolysis,and then dissolved and regenerated to form membrane.Single factor optimization combined with the corresponding surface,the preparation process of MCC was obtained:HCl(wt%)=8%,t=60 min,T=65?,and the yeild of MCC was 95.03%.FTIR and XRD analysis of the prepared MCC and the standard sample showed that there was no difference between the two,and the crystallinity of MCC was improved compared with cellulose.The prepared MCC film was analyzed,and found that the formation mechanism and crystal structure changed were consistent with cellulose,the thermal stability decreases after formation.In terms of performance research,it was found that the mechanical properties and separation performance have been improved as a whole.With the same content of 7%,the tensile strength of the MCC menbrance was6.52 MPa,which was 58.6%higher than the 4.11 MPa of the the cellulose membrane.Increase to 29.72 L/(m~2·h),and the rejection rate was 95.7%.4.The performance of the membrane was further inproved by preparing a composite membrane.The MCC and jute MCC were blended to prepare a rubescens/jute blend membrane.The performance of the blend membrane was studied according to the different proportion of jute.Through FTIR analysis,it was found that no chemical reaction occurred after the blending of jute and MCC,and the fiber structure did not change.Through XRD,it was found that as the proportion of jute increases,the crystal structure did not change,but the crystallinity was reduced.Through SEM analysis,the microstructure was best when the proportion of jute was 60%,according to the light transmittance,the proportion of jute was40%-60%,the compatibility of MCC and jute was the best,the thermal stability did not change much.For mechanical properties,the tensile strength was the highest,which was 15.5 MPa and the elongation at break was 29.61%when the ratio of jute was 40%.For separation properties,the water flux decreases,and the maximum was 20.54 L/(m~2·h),but the rejection rate was increased and stabilized to about 95.0%.Finally,the stability of menbranes was investigated.The stability of the rubescens/jute blend membrane and stability of cellulose membrane had little change,but the syability of MCC membrane was poor as whole,the swelling degree of the blend membrane in water was the lowest compared with other membranes,the swelling degree was 7.75%,30.13%in alkaline solution,23.98%in acid solution and1.25%in organic solution.Generally speaking,the stability is better.The material provides a new cellulose raw material.