Study Of Ternary-component Deep Eutectic Solvents To Prepare Jute Noil Nanocellulose

Jute is widely used in China,but a lot of noil will be produced in the textile processing,and its high-value recycling is less,resulting in the waste of raw materials.As a green solvent,deep eutectic solvents（DES）is cheap and easy to prepare.It has a good development prospect to prepare jute noil nanocellulose by DES to realize high-value recycling of jute noil.Therefore,in order to realize the high-value recycling of jute noil,improve the dissolving effect of DES on jute noil,and compare the dissolving performance of different DES components and the synergistic effect of three components on the performance of nanocellulose,this subject takes jute noil waste from textile processing as raw material,and uses different metal chlorides to form ternary-component deep eutectic solvents（3c-DES）with choline chloride-oxalic acid dihydrate（Ch Cl-OAd）respectively,which is used to prepare nanocellulose,and the prepared nanocellulose was used to prepare composite films with polyvinyl alcohol（PVA）.The research contents are as follows:（1）Five different metal chlorides（Zn Cl₂,Li Cl,Mg Cl₂·6H₂O,Fe Cl₃·6H₂O,Al Cl₃·6H₂O）were mixed with Ch Cl-OAd to form 3c-DES,which was used to prepare jute noil nanocellulose.It is found that 3c-DES formed by adding Zn Cl₂is not suitable for preparing nanocellulose,while 3c-DES formed by introducing Li Cl,Fe Cl₃·6H₂O and Al Cl₃·6H₂O can successfully prepare short rod-shaped cellulose nanocrystal（CNC）from jute noil.Among them,3c-DES formed by Mg Cl₂·6H₂O can be used to prepare nanocellulose,but its size is large and its thermal stability and crystallization performance are relatively poor.Adding Fe Cl₃·6H₂O and Al Cl₃·6H₂O to 3c-DES to prepare nanocellulose increased the crystallinity by 10.64%,but the thermal property and yield decreased.The yield and crystallinity of nanocellulose prepared by 3c-DES with Li Cl increased,but the thermal property decreased slightly.（2）Orthogonal experiments were designed for the process parameters of preparing nanocellulose by adding Li Cl,Fe Cl₃·6H₂O and Al Cl₃·6H₂O,and the optimal process of preparing nanocellulose was explored by range analysis and variance analysis.Among them,the optimal process for preparing jute noil nanocellulose by 3c-DES formed by Ch Cl-OAd-Li Cl is as follows:the molar ratio of OAd:Ch Cl:Li Cl is 2:1:0.1,the solid-liquid ratio is 1:25,the reaction temperature is 80℃,and the reaction time is 4h.The optimum process for preparing jute noil nanocellulose from 3c-DES formed by Ch Cl-OAd-Fe Cl₃·6H₂O is as follows:the molar ratio of OAd:Ch Cl:Fe Cl₃·6H₂O is 2:1:0.3,the solid-liquid ratio is1:50,the reaction temperature is 80℃,and the reaction time is 4h.The optimum process for preparing jute noil nanocellulose from 3c-DES formed by Ch Cl-OAd-Al Cl₃·6H₂O is as follows:the molar ratio of OAd:Ch Cl:Al Cl₃·6H₂O is 2:1:0.1,the solid-liquid ratio is 1:50,the reaction temperature is 80℃,and the reaction time is 4h.（3）For the preparation of cellulose nanocrystal containing lignin（LCNC）by adding Li Cl,Fe Cl₃·6H₂O,Al Cl₃·6H₂O into 3c-DES,it was found that 3c-DES formed by adding Li Cl,Fe Cl₃·6H2O and Al Cl₃·6H2O could successfully prepare LCNC with short spindle shape from jute noil raw materials,and its size was smaller than that of CNC made by3c-DES.All LCNC have absorption peaks representing the stretching vibration of lignin aromatic ring C=C in Fourier infrared spectrum,which confirms the existence of lignin in LCNC,and there are small absorption peaks around 1725cm^-1,which is beneficial to the separation and stability of LCNC.The maximum thermal decomposition temperature of all LCNC is about 350℃,and all LCNC have good thermal stability,but the crystallinity and yield are lower than those of CNC.（4）The prepared CNC and LCNC were compounded with PVA in different proportions to form films.Nano-cellulose with small particles and dispersed distribution exists on the surface of the composite film with 0.5wt%CNC and LCNC,and the composite film with other additions has different degree of agglomeration.The transmittance of CNC/PVA film and LCNC/PVA film in visible light range is about 90%.The transmittance of LCNC/PVA film decreased greatly in the near-ultraviolet wavelength range,and the transmittance of the composite film with 1wt%LCNC in UVA and UVB wave bands decreased by 33.25%and60.88%respectively compared with that of pure PVA film,which had obvious absorption effect on near-ultraviolet light.Compared with pure PVA film,the initial decomposition temperature and maximum thermal decomposition temperature of CNC/PVA film and LCNC/PVA film are higher,and the maximum thermal decomposition temperature of the film with 1wt%LCNC film is increased by 17.4%compared with pure PVA film.Compared with pure PVA film,the average breaking strength of CNC/PVA film and LCNC/PVA film is increased,and the increasing range is 12%～42%.