One-step Electrochemical Preparation And Application Of Conductive Filter Membranes Based On Graphene And Polyaniline

Electrofiltration is an effective method to improve the anti-fouling performance of microfiltration membranes.Polyaniline?PANI?has become a general material for the preparation of conductive filter membranes by scholars because of its excellent environmental stability,high conductivity,relatively low cost,special doping mechanism,and other advantages.However,using the conductive polymer membranes for the water treatment through electrofiltration,the conductive polymer must have stable conductivity in the water and harsh conditions.Therefore,improving the conductivity of the PANI membranes,and thus improving the anti-fouling performance of the membranes is the main content of this paper.In this paper,the PANI membrane was prepared by the non-solvent induced phase separation?NIPS?method,and then the graphene?Gr?was synchronously stripped and assembled on the surface of the PANI membrane through the one-step electrochemical method to prepare the Gr/PANI conductive filter membrane.The influence of applied voltage on the anti-fouling performance of the membranes was investigated,and the yeast suspension of 2 g/L was used as the feed of the fouling model.The properties of the as-prepared membranes were studied systematically by SEM,EDX,FTIR,Raman,XRD,AFM,membrane pore structure,water contact angle,etc.The results showed that after Gr was assembled on the surface of the PANI membrane,the conductivity increased from 0.97 S m^-1 for the PANI membrane to 1.51 S m^-1 for the Gr/PANI membrane.When the pressure and speed of the feed were 0.04 MPa and 1.6 L min^-1 respectively,compared with the PANI membrane before modification,the Gr/PANI membrane had better anti-fouling performance when the electric field E=1V was applied,the average flux of the Gr/PANI membrane was approximately 1.4 times that of the PANI membrane,the increased percentage of the total permeation flux for the Gr/PANI membrane was 109%,whereas that for the PANI membrane was only 78%.To reduce the adverse effect of the randomly dispersed Gr sheets and the poor electrochemical stability of the PANI membrane,thus improving the conductivity of the Gr/PANI membrane,in this paper,after using 1 mol/L HCl to dope the PANI membrane,a one-step electrochemical method with lowering the applied voltage was performed to prepare the Gr/mPANI membrane.The structure and properties of the prepared membrane were analyzed.The conductivity of the final obtained Gr/mPANI membrane was improved by dozens of times compared with the original PANI membrane,which could reach 40.5 S m^-1.The results of the anti-fouling experiments showed that the Gr/mPANI membrane under the electric field of E=1V had better anti-fouling performance,and the increased percentage of the total permeation flux was about 162%.While the acid doping process which need 24h greatly increased the preparation time of the Gr/mPANI membrane.Therefore,a further improved preparation method of the GO/PANI membrane was proposed:the graphite foil was firstly pretreated by electrochemical intercalation,subsequently,the PANI membrane was changed into the acid-doped state by the one-step electrochemistry and the GO/PANI conductive membrane with conductivity 55.6 S m^-1 was prepared,which greatly shortened the preparation time to less than 3h.The structure and performance of the GO/PANI membrane were also systematically studied,and the experiment results of the anti-fouling performance with the applied electric field E=1V also proved that the GO/PANI membrane had the excellent anti-fouling performance that the increased percentage of the total permeation flux reached 166%.The above results certified that the prepared Gr conductive membranes had big potentials to be used in electro-filtration areas.Moreover,the one-step electrochemical method also provided a promising strategy for the combination of Gr materials with conductive polymers to produce separation membranes.