Study On The Modification Of PVDF Mixed Matrix Membrane Membrane By Zeolite Imidazole E Ester Framework(ZIF-8)

In this paper,porous nano-particles ZIF-8/PVDF modified membranes were prepared based on functional metal-organic framework（MOFs）nanoparticles with high photocatalytic degradation ability for printing and dyeing wastewater.Zeolitic imidazolate framework（ZIF-8）in three particle sizes（40,70 and 100 nm）was prepared through both solvothermal and hydrothermal methods and employed to decorate polyvinylidene fluoride（PVDF）.The finger-like macro-voids,sponge-like poly-porous morphology and surface roughness of prepared membranes were characterized by SEM and AFM microscopy.The FTIR spectrum and XPS analysis bear out the chemical component.ZIF-8 has the characteristics of higher porosity and appropriate pore size,which is a condition for improving the permeability and pollution resistance of the modified membrane.Results indicated that different ZIF-8s have different enhancement effects on PVDF MMM.100 nm ZIF-8 membrane possessed pure water flux（PWF）of 350 Lm^-2h^-1,which was ten times more than the bare membrane(30 L·m^-2·h^-1),and OVA flux recovery ration（FRR%）is 98%.40 nm ZIF-8 membrane owned BSA FRR%of 98.4%.The 70nm ZIF-8 showed the best mechanical properties.The dynamic contact angles of UP-Z70 ranged from 104.5°to 62.5°within 180 s.Furthermore,pore size distribution,molecular weight cut-off（MWCO）and porosity were also researched to evaluate the MMM.The dislodge of Reactive Black KN-B,Reactive Red 3BS and Reactive Brilliant Blue KN-R dyes by MMM were studied under different dye concentrations and transmembrane pressures.The membrane can provide selective separation methods for dyes and Reactive Brilliant Blue KN-R up to 99%.Overall,the permeability,hydrophilicy,anti-fouling performance and wastewater treatment of modified membranes were regulated by the ZIF-8 in a steerable blending reaction modification process.To investigate the performances of prepared membranes on the basis of good hydrophilicity,expand the application range and improve its practical application performance of nano hybrid membrane,ZnO@ZIF-8 and SiO₂nanohybrid were chosen as the additive.Compared with other membranes,SZPM4 membrane has excellent hydrophilicity.The rejection rate of bovine serum albumin（BSA）was more than 95%,and the pure water flux reached 395 L·m^-2·h^-1.BSA had the highest flux recovery of SZPM4 membrane（94%）.The photocatalytic effect of the modified membrane can significantly improve the separation efficiency of 4-nitrophenol wastewater.Among them,4-NP SiO₂:ZnO@ZIF-8 membrane can achieve a higher separation effect under light conditions,and the flux in the filtration process is maintained at about 321 L·m^-2·h^-1.The common reactive black KN-B,reactive red 3BS,reactive bright blue KN-R,p-nitrophenol（4-NP）dyes are typical pollutants in wastewater.The removal behavior of ZIF-8/PVDF under different dye concentrations and transmembrane pressures was studied.The membrane can provide a selective separation method for dyes and reactive brilliant blue KN-R,up to 99%.When the degradation rate of 4-NP by SiO₂:ZnO@ZIF-8/PVDF membrane is 81.5%,the rate constant(Kapp/min^-1)is 0.211 min^-1.After a long time of experiments,SiO₂:ZnO@ZIF-8 membrane kept high flux and rate for 4-NP under light condition.