Preparation And Properties Of Piezoelectric Ultrafiltration Membranes By Doping PVDF With Modified Inorganic Nano-particles

Ultrafiltration technology has the characteristics of low using pressure,high separation coefficient,large water flux and simple equipment.It has important significance in environmental water purification technology.However,membrane fouling caused by membrane surface chemistry,membrane-solute and solute-solute interaction in ultrafiltration process seriously affects the development of ultrafiltration technology.At present,there is no effective way to completely solve the problem of ultrafiltration membrane fouling.Nano-Si O₂/PVDF ultrafiltration membranes,Nano-Si O₂/PVDF piezoelectric ultrafiltration membranes,Nano-Zn O/PVDF ultrafiltration membranes,Nano-Zn O/PVDF piezoelectric ultrafiltration membranes and Nano-Zn O/PVDF piezoelectric ultrafiltration membranes were prepared using modified inorganic nanoparticles doped with PVDF on the basis of hydrophilic modification and high voltage direct current electric field polarization treatment.Membrane performance was studied by using Bovine Serum Albumin（BSA）as a characteristic pollutant.The simulation results of piezoelectric ultrafiltration membrane were coupled with COMSOL Multyphysics software,and the self-cleaning mechanism was analyzed.The results showed that the hydrophilicity,piezoelectric properties and anti-fouling ability of UF membranes could be improved by doping appropriate amount of inorganic Nanoparticles.Excessive doping would lead to the increase of the compactness and density of the membrane and the performance of the membrane would be decreased.Moreover,the increase of doping amount of inorganic nanoparticles would aggravate the agglomeration phenomenon and caused membrane defects.During the polarization process,the electric energy was consumed by the large leakage current,which caused excessive dielectric loss in the polarization process,reduced the piezoelectric activity of the piezoelectric ultrafiltration membrane,and impairs the performance of the piezoelectric ultrafiltration membrane.The piezoelectric constant of piezoelectric ultrafiltration membrane obtained by high voltage DC electric field polarization was close to or even higher than that of common piezoelectric materials,and the piezoelectric performance was excellent.Under the excitation of AC electric field,the membrane produced in-situ micro-vibration,which reduced the adhesion of BSA molecules on the membrane surface,promoted the self-cleaning performance of the membrane and alleviated the formation rate of membrane fouling.The simulation results showed that the stress on the membrane pore was relatively larger and the in-situ micro-vibration was stronger,which made the pulse flow in the membrane pore and increased the pure water flux.However,it also caused the membrane pore to pass through the BSA molecules intercepted in the pore and reduced the interception efficiency.This study provides a new direction for the development of self-cleaning ultrafiltration membranes and a theoretical basis for the anti-fouling research of ultrafiltration membranes.