Study On Preparation And Adsorption Properties Of Regenerated Cellulose-Chitosan Composite Aerogel

In the face of the increasingly serious problem of organic dye pollution in water,traditional porous adsorption materials limit their application in the field of organic dye adsorption and separation due to their low adsorption capacity and difficult regeneration.In this paper,a variety of composite aerogel materials were prepared by using low-cost regenerated cellulose（RC）and chitosan（CS）as raw materials,and physical crosslinking by green heat treatment process and chemical crosslinking by glutaraldehyde were used to obtain stable three-dimensional porous structures.Its mechanical strength,efficient adsorption efficiency and reusability were studied,and the adsorption and separation properties of various dyes in water were tested.The specific research content is as follows:（1）Firstly,using N-methylmorpholine-N-oxide monohydrate（NMMO·H₂O）as the green solvent of cotton pulp fiber（CP）,a low-cost regenerated cellulose hydrogel was obtained.After being combined with chitosan,the regenerated cellulose/chitosan aerogel（RC/CSA）was prepared by freeze-drying.In addition,CP and CS were directly combined to prepare cotton pulp fiber/chitosan aerogel（CP/CSA）through freeze-drying.The porosity of the RC/CSA sample is 98.5%,which is higher than the 97.8%porosity of CP/CSA.The filamentous/flat regenerated cellulose fibers in RC/CSA reduce the agglomeration of chitosan into sheets in the composites.The adsorption capacities of CP/CSA and RC/CSA for low concentration MO are 86.9 mg/g and 117.4mg/g,respectively.（2）In order to improve the mechanical strength and adsorption efficiency of RC/CSA,a stable regenerated cellulose/chitosan composite aerogel（RC/CSA-DHT）was prepared by physical crosslinking of RC and CS in RC/CSA through a simple green heat treatment process.After 10 times of 80%strain compression cycles,the maximum stress and height of the stress-strain curve did not decrease.The maximum adsorption capacity of RC/CSA-DHT to MO in water is 667 mg/g.After three times of filtration and separation,the removal rate of MO reached 98.20%.The adsorption-analytical cycle experiment confirmed the reusability of RC/CSA-DHT,and the adsorption capacity remained 60%after 5 times of regeneration.（3）In order to further improve the stability and adsorption capacity of acidic environment,RC/CSA was chemically crosslinked with glutaraldehyde（GA）,and high mechanical strength regenerated cellulose/chitosan composite crosslinked aerogel（RC/CSCA）was obtained.Its porosity is 97.36%and its density is as low as 13.92mg/cm³.The structure of the material remained good after soaking in pH=2 water for48 h,indicating that the stability of the sample in water was improved after chemical cross-linking.Under wet condition,the maximum stress and height of the sample did not decrease after 10 times of 80%compressive strain cycle.RC/CSCA showed strong selective adsorption for anionic dye MO through mixed adsorption experiments.The maximum adsorption capacity of RC/CSCA to MO is 742.68 mg/g.After 10 adsorption-desorption cycles,the adsorption capacity was still 94.57%.