Mulberry Branch Cellulose Extracted By DES And The Electrical Conductivity And Antibacterial Modified Material Preparation

Mulberry is an important economic plant,which is widely distributed in different ecological and geographical areas.Mulberry leaf is the main food of silkworm.Mulberry leaf,mulberry root and mulberry fruit are rich in flavonoids,alkaloids,polyphenols and other bioactive substances,which have high medical health care value.However,the content of these bioactive substances is generally low,and the extraction methods are complicated,which accounts for a very low proportion of mulberry resources.Meanwhile,the mulberry branches are mostly abandoned in the field and even burned,which causes a great burden on the local ecological environment.Mulberry is a kind of hardwood,its cellulose content is about 52%.Natural cellulose has the properties of non-toxic,regeneration and degradation.In this study,the mulberry branch was used as experimental material,and the cellulose was extracted from mulberry branch by DES.The content of cellulose is determined by automatic cellulose analyze machine,and the best method to extract mulberry branch cellulose is chosen based on the content.After that,we prepare NCC by sulfuric acid and studied the differences,such as crystallinity and heat stability in between.The TE-NCC/[RGO]_n films are made by LBL self-assembly method and the AgNP-PD-TENCC antibacterial composite is prepared by dopamine hydrochloride and AgNO₃,then we study the best condition of these process.The specific research results of the process are as follows:1.Separation of cellulose from mulberry branchBased on mulberry branches,the extraction process was optimized by choline chloride oxalic acid separation and single factor and response interview tests,and the experiments showed that the optimal conditions for cellulose extraction from mulberry branches by deep eutectic solvent(DES)were as follows:liquid-solid ratio is 20.628:1,reaction temperature is 116.543°C,and reaction time is 2.891 h,under which the predicted value of cellulose content is 91.64%.According to the test operability,the test conditions were fine tuned as follows:liquid-solid ratio is 20:1,reaction temperature is 117°C,and reaction time is 2.9 h.Under this condition,the content of tested cellulose was verified to be 90.72%,which basically coincided with the response surface predicted value.Scanning electron microscope(SEM)analysis showed that the cellulose surface treated by DES was relatively smooth and there were fine ravines,which indicated that DES could effectively dissolve lignin and hemicellulose in mulberry branch powder.Fourier infrared(FT-IR)and thermogravimetric(TG)analyses showed that most lignin and hemicellulose in the mulberry flour raw material were desalted.And the quality of cellulose extracted was superior.X-ray diffraction(XRD)analysis showed that the crystal forms of the extracted isolated celluloses were not changed,and at the same time,the crystallinity was significantly improved.All in all,the des method can effectively remove the non cellulose components from the raw materials of mulberry branch powder to obtain the component purer cellulose.2.Preparation and characterization of nanocellulose from mulberry branch celluloseMulberry nanocellulose prepared from mulberry branch cellulose by acid hydrolysis the optimal conditions for acid hydrolysis by single factor tests were as follows:time is 60min,temperature is 60°C,solid-liquid ratio 1:20(g/m L),and sulfuric acid concentration64%.The as prepared mulberry branch nanocellulose was analyzed by FT-IR,and its structure did not change significantly and was still type I cellulose.But its dispersity in water is general and needs to be further improved.3.Preparation and characterization of TE-NCC/[RGO]n filmsTo improve the additional value of mulberry branch cellulose,TE-NCC-[RGO]_nconductive composite films were prepared through a layer by layer self-assembly method.To improve the dispersity of mulberry branch nanocellulose in aqueous solution,it was subjected to oxidative treatment,then the film was dried by suction drying and combined with graphene oxide,and finally the TE-NCC-[RGO]_n conductive composite film was obtained by reduction.The test results showed that the electrical conductivity of the composite membranes was closely related to the number of self-assembly times,which was significantly improved after the self-assembly times reached 25 times and remained stable after 35 times.Meanwhile,Raman spectroscopy and infrared spectroscopy analysis test results showed that after reduction treatment,graphene oxide was effectively reduced to become reduced graphene oxide.The results showed that TE-NCC-[RGO]_n films exhibit excellent electrical conductivity.4.Preparation of AgNP-PD-TENCC antibacterial composite materialAgNP-PD-TENCC composites with antibacterial effect were prepared by hitchhiking nanosilver particles onto oxidatively pretreated mulberry nanocellulose and using dopamine hydrochloride as a binder and reducing agent,and the amount of dopamine hydrochloride added influenced the diameter of nanocellulose by TEM analysis,both in dopamine hydrochloride and oxidized nanocellulose.The optimum was obtained at a rice cellulose feed ratio of 1:1.Scanning electron microscope(SEM)analysis showed that,Agnanoparticles can be uniform Ly dispersed on mulberry branch nanocellulose after treatment,avoiding the agglomeration of Agparticles.The antibacterial experiment showed that the addition of mulberry branch nano cellulose could improve its antibacterial effect under the condition of the same silver content.