Synthesis, Properties And Applications Of Cellulose Fatty Ester Obtained By Homogeneous Reaction

This thesis is focused on the preparation, characterizations and adsorbing performance of cellulose fatty esters obtained under homogeneous reaction (HRC) with fatty chloride in the media of lithium chloride/N,N-dimethylacetamide (LiCl/DMAc).Cellulose was firstly activated and dissolved in the system of LiCl/DMAc. The optimum preparation condition was explored and obtained:the cellulose was first pretreated by 10%NaOH aqueous solution at 0℃for 5h, soaked in the ethanol solution for 5h and in DMAc solution for 8h respectively, and then treated by ultrasonic waves for 2mins. Due to the pretreatment, the crystalline structure of cellulose was altered and therefore facilitated to the following homogeneous reactions. Regenerated cellulose from LiCl/DMAc solution was studied by XRD and TGA. The XRD results showed that the crystal structure of cellulose was destroyed to some extent and the polymorph of regenerated cellulose turned from celluloseⅠinto celluloseⅡ. The TGA results showed that the thermodynamic stability of the product was reduced,Secondly, cellulose esters were synthesized homogeneously in the system of LiCl/DMAc with fatty chloride successfully. The optimum conditions were based on the results of single factor and orthogonal tests as follows:the dosage of lauroyl chloride 1.6 mol, reaction temperature 100℃, reaction time 8h and the amount of catalyst 1.2 mol. The ensuing materials were characterized by FTIR,1H-NMR, XRD, TGA, contact angle and SEM. The FTIR and 1H-NMR results confirmed the formation of carbonyl bond and indicated that the esterification was indeed occurred. The XRD results showed that resulting cellulose fatty esters were amorphous. The TGA results showed that the thermodynamic stability of the product was reduced and the glass transition range of cellulose fatty acid esters became broad. Dynamic contact angle measurements results revealed that the contact angle of water on the films of cellulose fatty esters increased with the increasing esterification extent. SEM images exhibited the morphology change before and after chemical modifications for cellulose fibers.Thirdly, as adsorbent, cellulose esters showed excellent performance in absorbing organic molecules in waste streams. Compared with cellulose, cellulose esters had a higher adsorption capacity for toxic small organic molecules. What's more, the adsorption capacity of cellulose esters was found highly correlated with the DS of esterification. The adsorption of organic molecules in neutral wastewater on cellulose fatty ester particles fitted well with Freundlich model and a multilayer of adsorption may present. Recycling testes showed that the esterified fibers can be reused without negligible loss of its adsorption capacity through repetitive washing.