| This study focused on the preparation of a new kind of material,zwitterionic cellulose acetate(ZCA).It was used as a membrane material to solve the problem of membrane fouling during the separation of ultrafiltration membranes,at the same time,it was blended with graphene oxide(GO)physically to get the ZCA/GO spherical adsorption material,which could improve the adsorption efficiency and the regeneration rate.The more detailed conclusions were summarized as follows:(1)Firstly,the preparation of the zwitterionic cellulose acetate(ZCA)was via a three-step procedure consist of oxidization,Schiff base and quaternary amination reaction,and the chemical structure changes of ZCA were analyzed by FT-IR and XPS,which proved the ZCA was synthesized successfully.The thermal stability of ZCA was found declined by the result of TGA.Viscosity tests showed that although the viscosity decreased after modification,it still had a higher molecular weight.The ZCA not only retained the original non-toxic and biodegradable excellent properties,but also was expect to introduce the advantages of strong hydrophilicity,anti-contamination of zwitterion,and then increase the value of cellulose acetate.(2)Secondary,the antifouling ZCA ultrafiltration membrane was fabricated by the non-solvent-induced phase separation method(NIPS).The morphologies,surface chemical structures and compositions of the obtained CA and ZCA membranes were thoroughly characterized by field emission scanning electron microscopy(FE-SEM)with energy dispersive X-ray(EDX)spectroscopy,FTIR and XPS,respectively.Meanwhile,the thermal stability,porosity and average pore size of two investigated membranes were also studied.As a result,the ZCA membrane displayed significantly improved hydrophilicity and water permeability compared with those of the reference CA membrane,despite a slight decrease in the protein rejection ratio.According to the cycle ultrafiltration performance of bovine serum albumin(BSA)solution and protein adsorption experiment,ZCA membrane exhibited better flux recovery property and fouling resistant ability,especially irreversible fouling resistant ability,suggesting superior antifouling performance.This new approach gives polymer-based membrane a long time life and excellent ultrafiltration performance,and seems promising for potential applications in the big molecule matters separation.(3)Finally,after zwitterionic cellulose acetate(ZCA)and graphene oxide(GO)were physically blended,a novel ZCA/GO spherical adsorbent was prepared by sol-gel method and used to remove Cu2+ and Cd2+ from aqueous solution.Scanning electron microscopy(SEM)was used to characterize the surface morphology of the material before and after adsorption.The results showed that the surface of the material was uniformly distributed with a large number of regular pores and a crosslinked network structure was present inside.X-ray diffractometer(XRD)test results show that the prepared ZCA/GO spherical adsorption material has no obvious crystal structure.For adsorption,effect of time,temperature and pH,adsorbate concentration was investigated;different adsorption models were also evaluated.The results showed that the maximum adsorption capacity was 32.03 mg/g for Cu2+ and 27.55 mg/g for Cd2+,observed at pH 6 and 298 K.Simultaneously,the adsorption isotherms were well-fitted to the Langmuir model,and kinetics study implied that the adsorption process was attributed to pseudo-second-order model.Further regeneration experiments revealed that the adsorption of ZCA/GO was about 86%of the initial saturation adsorption capacity after repeated use 5 times,indicating that they are promising absorbents for practical application in industry. |
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