Preparation,Characterization And Application Of Nanocellulose And Its Modified Products

The raw materials obtained from renewable biological resources have advantages such as relatively low cost,natural environment friendly,easy availability,renewability and non-toxicity,etc.In this thesis,cellulose was used as the starting material.After the experimental conditions were controlled,granular and flake nanocellulose NCC and FNC were prepared,respectively,and the modification of nanocellulose was performed by amination and metal complex modification.The products NCC-EDA and Cu₂O/FNC were investigated,and the application of NCC-EDA and Cu₂O/FNC in heavy metal ion detection and photocatalytic degradation of black liquor was investigated.The specific research content is as follows:Nanocrystalline cellulose（NCC）with particle size range of 15-35 nm was prepared by mixed acids/ultrasound treatment of microcrystalline cellulose.The obtained NCC was first treated by thionyl chloride（SOCl₂）to be chlorinated,dehydrated and carbonized,and oxidized.Then it underwent amination modification and cellulose-based fluorescent nanoparticles（NCC-EDA）were obtained,the structure and optical property of which were characterized by elemental analysis,TEM,BET,FT-IR,XRD,TG-DTA,XPS,UV-Vis,PL,etc.Furthermore,NCC-EDA was studied as fluorescent probe to detect metal ions in water.The results show:NCC-EDA is vesicle-like porous particles formed by EDA linking and intertwining SOCl₂ treated NCC,the surface of NCC-EDA is rich in oxygen,nitrogen and sulfur-containing functional groups.the particle size distribution is largely between 40-50 nm,NCC-EDA has good dispersity in water and exhibits good adsorption and fluorescence emission ability;in the presence of trace Pb²⁺ion,our NCC-EDA shows selective fluorescence quenching,and its detection limit of Pb²⁺is as low as 0.024μM,indicating it is an extremely efficient fluorescent sensor for Pb²⁺ion.Using microcrystalline cellulose as raw material,the nano-cellulose（FNC）was prepared by the ultrasonic/mixed acid binding method,and Cu₂O/FNC nanoparticles were prepared by compounding Cu₂O particles synthesized in situ.The structure and optical properties of Cu₂O/FNC were tested by FT-IR,XRD,TEM,UV-vis,and other methods and the Cu₂O/FNC was applied to photocatalytic degradation black liquor,studing its photocatalytic activity.The results showed that Cu₂O/FNC is a regular layered structure,,and it can absorb the UV visible light.So it can be treated as a visible light catalyst to handle cotton pulp cooking black liquid.After reaction for 180min,in addition to the structure of heterocyclic compounds containing nitrogen,most of the organic matter in waste water can be degraded,and the COD_cr removal rate of the black liquid reached 82.42%,which is much higher than photocatalysis efficiency of commercially visible P25-H₂O₂.