Study On Bionic Silicon-based Coated Polyvinylidene Fluoride Membrane And Its Oil-water Separation Performance

Oily wastewater has caused serious pollution to the environment.Polymer membrane can play an important role in alleviating the pressure of water stress,but the hydrophobicity of the membrane reduces the reusable performance.Therefore,improving the hydrophilicity is the key to solving this problem.The bionic coating system has been extensively researched and implemented in the surface engineering of various materials to achieve multi-functionalization.Dopamine is a typical method to enhance the surface hydrophilicity.Although it is simple and effective,there are still some inherent limitation s,such as high cost and many restrictions.Therefore,this topic propose d two silicide-like dopamine coating systems,using infrared spectroscopy?FTIR?,scanning electron microscopy?SEM?,X-ray photoelectron spectroscopy?XPS?and other tests to charact erize changes in the film surface structure,and characterizing the effect of different coating concentration and time on the membrane wetting performance through a variety of test systems.Further,we explored the effect of surface hydrophilization modification on the membrane oil-water separation performance.We used commercial polyvinylidene fluoride?PVDF?microfiltration membranes as the substrate,imitating the mussel chemical system,using catechol?CA?and 3-aminopropyltriethoxysilane?APTES?on PVD F microfiltration membranes to obtain a modified film.The results showed that the coating had been successfully prepared and the film layer was relatively uniform;compared with the original PVDF film,the modified film ha d a significant improvement in wetting performance.Taking MF-C/A-0.1/0.6 as an example,the specific performance was that the initial water contact angle was reduced from 112° to 35°,and reduced to 0° within 4 s;the water flux was increased to 16000 L m^-2 h^-1;the retention performance of toluene emulsion also increased to 99.0%.The results showed that by changing the time of coating modification and the concentration of CA/APTES,the hydrophilicity of the membrane could be adjusted,thereby affecting the performance of the separation membrane.It was further proposed to apply bionic material system tannic acid?TA?and 3-mercaptopropyltriethoxysilane?MPTES?on the PVDF microfiltration membrane.This method could also obtain a hydrophilic coating on the surface of the microfiltration membrane to make the separation membrane hydrophilic.The water contact angle of the modified membrane MF-T/M-0.1/0.2 could be reduced to 0° in 6-8s.Tests such as water contact angle and pure water flux showed that the modified membrane had good hydrophilicity.By adjusting the coating modification time,the hydrophilicity could be adjusted;the rejection for toluene emulsion was around 90.0%.In addition,this method ha d certain guiding significance for broadening and optimizing the application conditions of bionic dopamine surface functionalization.