Preparation And Application Of Modified Bagasse Cellulose Cation Exchange Membrane

The ion exchange membrane is a polymer electrolyte having selective permeability to the ions in solution,and its surface contains functional groups.Because the ion exchange membrane has the characteristics of separation and selection,as well as energy saving,high efficiency and environmental protection,it is applied to seawater desalination,industrial waste recycling,chemical separation,food processing and many other fields.At present,although the ionexchange membrane has attracted people's extensive research and application,but by phthalic anhydride modified bagasse cellulose to prepare ion exchange membrane research is still relatively small.in this study,a cellulose membrane with selective permeability for cations was prepared by using bagasse cellulose,which is a rich and environmentally friendly natural macromolecule,and phthalic anhydride as a modifying agent.At the same time through a variety of physical and chemical means to make the ion exchange membrane has a good moisture content,swelling,ion exchange capacity and a certain degree of mechanical strength and other properties.And the ion exchange membrane is used in the electrodialysis device to treat ammonia nitrogen wastewater.The main research contents are as follows:First,the phthalic anhydride was used to modify the cellulose bagasse cellulose,the carboxyl group was introduced into the cellulose,and the optimum reaction conditions were obtained by the response surface analysis method:the dosage of anhydride 7g,the ultrasonic pretreatment time 60min,reaction time 5 7min,reaction temperature 91?.Under these modified conditions,the yield of carboxylation was 13.45%.XRD,TGA and DTG were used to analyze the modified products.The results showed that the characteristic peaks of the carboxyl groups appeared in the modified products.The crystallinity of the cellulose did not change,the crystallinity decreased from 68.83%to 67.79%,The thermal stability of the modified cellulose is deteriorated.Second,the zinc chloride aqueous solution as a solvent,modified cellulose bagasse as a raw material for film experiment.The effects of different bagasse cellulose mass fraction and pore forming agent on the moisture content,swelling degree,ion exchange capacity and mechanical strength of ion exchange membrane were investigated.The results showed that the cationic exchange membrane was the best when the mass fraction of cellulose was 3.5%and the mass ratio of cellulose to cellulose was 2:1.Under these conditions,the performance index is:water content of 29.33%,swelling degree of 8.66%,ion exchange capacity of 0.98mmol/g,tensile strength of 0.84MPa.The results of ion exchange membrane show that there is no new functional group before and after film formation.The crystal form of cellulose changed from type I to type II,the crystallinity decreased from 68.83%to 47.66%,and the thermal stability decreased.Finally,the ability of ion exchange membrane to treat ammonia nitrogen wastewater was investigated by electrodialysis experiment.The effects of ammonia concentration,experimental voltage and electrolysis time on ammonia nitrogen removal rate were investigated.The results showed that when the concentration of ammonia in wastewater was 1500mg/L-2000mg/L,the treatment efficiency of ammonia was higher.Under the condition of the experiment voltage of 10V and the electrolysis time of 7h,the removal rate of ammonia nitrogen can reach 90.12%.