Research And Application Of Functional Properties Of Functionalized Carbon Materials/polyvinylidene Fluoride Hybrid Membranes

Polyvinylidene fluoride(PVDF),a promising polymeric membrane separation material,has broad application prospects in the membrane separation process because of its excellent chemical resistance,thermal stability and oxidation resistance.However,the inherent hydrophobicity of PVDF membrane is easy to cause membrane fouling.The solution to the problem of membrane fouling and how to realize the effective use of the membrane can be considered from the following two aspects:one is to select the appropriate modification method to improve membrane's own water treatment and anti-fouling performance.The second is to monitor the fouling of the membrane in time,so that the membrane can be cleaned timely to prolong the service life of the membrane.Carbon nanotubes(CNT)have become the ideal nanofillers in polymeric membrane materials for their excellent mechanical,electrical and mechanical properties.Graphene oxide(GO),as a derivative of graphene,has good water dispersibility due to its abundant oxygen-containing functional groups at the edges of the sheet.Their excellent properties have aroused people's attention.In this paper,the original multiwalled carbon nanotube(MWCNT)were carboxylated to form oxidized multiwalled carbon nanotube(OMWCNT)by mixed acid treatment and used them as nanofillers.While using a modified Hummers method to prepare graphene oxide and formulated into a certain concentration as a membrane-forming coagulation bath.Functionalized carbon nanomaterials/PVDF hybrid membranes were prepared by a combination of mixed matrix and solution coagulation bath.The effect of the addition method and their addition amount of carbon materials on the performance of the membrane was investigated.The optimal method and the optimal content are determined and the mechanism of improving the performance of the membrane is analyzed.The test results show that the pore structure of the hybrid membrane has been significantly improved,the roughness,hydrophilicity,water flux,rejection rate,mechanical and electrical properties have been significantly increased compared with the pure PVDF membrane.The PVDF/OMWCNT/GO has the best comprehensive performance.The effect of the amount of OMWCNT on the properties of the membrane was further discussed under the optimum addition mode of carbon material.The results show that the separation performance of the hybrid membrane reaches the optimal when the addition amount of OMWCNT is 3 wt.%,.When the addition amount is 4 wt.%,the conductivity of the hybrid membrane reaches the saturation value.Finally,in view of the hybrid membrane has a certain conductivity,it can be used in membrane fouling sensor and the fouling degree of membrane can be analyzed by establishing the relationship between electrical parameters and the thickness of fouling layer so as to achieve the purpose of real-time monitoring and then provide a new idea for membrane fouling monitoring.