| Ultrafiltration(UF),the most common membrane separation process,is widely used in a variety of industrial processes,such as protein concentration and purification in biological engineering,extraction of whey in food and industrial wastewater treatment.Cellulose acetate(CA)is used for the manufacture of ultrafiltration membrane,for its unique advantages: low cost,renewable,good biocompatibility,good hydrophilicity and so on.However,in the process of membrane separation,the cellulose acetate based ultrafiltration membrane will face the problem of the separation efficiency descend.In order to improve the performance of cellulose acetate ultrafiltration membrane and to enable it to meet the requirements.We use inorganic nanoparticles halloysite nanotubes(HNTs),load the L-DOPA halloysite nanotubes(LPDHNTs)and graft KH792 halloysite nanotubes(KHNTs)as the modified material,to preparare composite ultrafiltration membrane by immersion precipitation phase catalysis,and then explore the permeability,hydrophilic,pollution resistance,mechanical properties of the membrane.We use halloysite nanotubes(HNTs)to modify cellulose acetate ultrafiltration membrane and to explore the impact of halloysite nanotubes on the structure and properties of CA ultrafiltration membrane.The HNTs /CA composite ultrafiltration membrane showed higher pure water flux,water content,porosity,pore size and hydrophilicity,however,the member surface roughness was increased.It was found that the HNTs/CA composite membrane pore structure connectivity and porosity enhanced.The membrane porosity increased from 55.3 % to 69.5 %;the water flux of water increased from 11.5 L·m-2·h-1 to 47.6 L·m-2·h-1,while maintaining a high rejection rate of protein.The membrane surface water contact angle decreased from 63.7° to 53.9°,in addition,the water flux recovery of the membrane from 65.7 % to 81.9%,based on above we can conclude that the composite membrane had good anti fouling ability.In order to meet the demand of the process of concentration in biological separation and purification of proteins,solve the antifouling problems in the process of separation,in this experiment,the surface modification of HNTs was carried out by using the characteristic of zwitterionic L-DOPA,and then use different content of LPDHNTs as an additive to prepare better permeability and antifouling properties CA-based ultrafiltration membrane.It was found that the pore size of the composite membrane increased from 11.2 nm to 34.4 nm,pure water flux increased by more than 8 times,while the rejection rate of EA was about 90 %.Besides,the hydrophilic and anti-pollution ability of the membrane have been greatly improved.The composite membrane surface changes smoother,which can reduce the protein adsorption on the membrane surface.After three cycles of testing,the water flux recovery rate of 90.1%.In view of the above,it can be applied to biological separation.The KHNTs /CA blend ultrafiltration membrane was prepared by solvent induced phase separation.The membrane was applied in wastewater treatment field to separate anionic dyes and heavy metals.It showed that the retention rate of anionic dyes Congo red was increased from 45.6 % to 92.1%.What is more,the rejection rate of heavy metal ion,the pure water flux,hydrophilic,surface smoothness and ability to resist pollution of the membrane were also significantly promoted.Regarding the above,the hybrid membrane can be used in the wastewater treatment. |
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