Preparation Of Antifouling Multi-walled Carbon Nanotubes /PVDF Membrane Using Gel Extracellular Protease Secretion Solution(EPS)as Gel Bath

Polyvinylidene fluoride?PVDF?membrane material has excellent chemical and physical properties and has been widely used in many fields such as environmental protection,chemical industry,food,medicine and biology in recent years.However,the extremely hydrophobic and easily contaminated surfaces of PVDF membranes have limited their development and application.In this paper,multi-walled carbon nanotubes?MWCNT?and polyvinylpyrrolidone K30?PVP?as additives and EPS solution as a gel bath to prepare a new type of flat membrane,in order to improve the hydrophilicity of PVDF membrane and increase the membrane anti-pollution performance,and The effects of each reagent on membrane performance were analyzed and the following results were obtained:PVDF was used as raw material,DMAc and DMF were used as solvents,and PVP and LiCl were used as additives to perform orthogonal experiments.Finally,the films prepared from PVP as additive with DMAc as additive?Group A?had better overall performance.The pure water flux is 2024 L/?m² h MPa?.The retention rate is kept above 95%within 30 minutes of operation,the total pollution rate is 78.3%,and the irreversible pollution is only 12.9%.This ratio is used for the next modification.On the basis of group A membranes,MWCNTs were added,and new membranes were prepared using EPS solution as a gel bath.The membranes were passed through a simulated test of wastewater simulated humic acid?HA?to examine their effects in practical applications.The addition of MWCNT to the blend membrane inhibits the formation of voids in the pores of the membrane and promotes the development of pores in the pores of the membrane.It also has a certain role in the hydrophilicity and average porosity.The MWCNT is tubular.The structure will form a capillary effect,which can increase the water flux by 4%-42%on the basis of the group A membrane.The EPS solution acts as a gel bath to form a sponge-like pore in the membrane.EPS solution as a gel bath can improve the hydrophilicity of the membrane,but its effect on the average porosity is not obvious,and it is beneficial to reduce pollution.When the PVP content remains unchanged,the Rir value decreases with the increase of MWCNT;when the PVP content decreases,the Rir value does not show a regular decrease when the content of MWCNYT increases,indicating that both MWCNT and PVP are present under this system.Contribute to the membrane's resistance to contamination.The three groups of membranes E?PVDF,PVP,MWCNT blend,pure water for gel bath?,F?PVDF,PVP,MWCNT blend,20%EPS solution for gel bath?,and H?PVDF,MWCNT blend,20%EPS solution for gel bath?cut off the HA solution and found that when the separate EPS solution was used as a gel bath,the rejection rate of HA on the membrane was increased from 54.3%?M0?to 70.9%?H0?;MWCNT/PVP was used as Additives have a significant positive effect on the retention rate and flux recovery,and the FRR value can reach over 80%.The J_W1 value decreased in order of F group,E group,and H group;the rejection rate of HA decreased in the order of E group,F group,and H group;the FRR value decreased in descending order of F group,E group,and H group.Rt and Rir values increase in order of H group,F group,and E group.Based on comprehensive performance considerations,the pure water flux of the F group is high,and its retention rate for HA is kept above 65%,which is higher than54.3%of the pure membrane M0,and the flux recovery is higher,and the irreversible pollution is below 35%.In the F group,the pure water flux of 3089 L/?m² h MPa?of F2?PVDF-15%,PVP/MWCNT-5%/0.3%,solvent-DMAc,gel bath-20%EPS solution?,the rejection rate of HA was 66%,the recovery rate of flux was 69.3%,and the irreversible pollution was 35.9%.It could be used as the membrane with the best effect.