Preparation Of Antifouling Ion Exchange Membrane Via Electro-deposition

Electrodialysis(ED)is a membrane-based separation process driven by a direct current(DC)voltage.It has been widely applied in brackish water desalination,organic acids recovery and wastewater treatment.However,membrane fouling,which increases the membrane resistance,shortens membrane life and increases energy consumption,has become a main limitation for wider applications of ED.Since most of the organic foulants are negatively charged,anion exchange membranes(AEMs)are more vulnerable to be fouled than the cation exchange membranes(CEMs).Increasing the hydrophilicity and negative charge density of AEMs is an effective way to solve the problem of membrane fouling.In this paper,the AEMs were modified by electro-deposition to improve their antifouling ability.Firstly,PSS modified membranes were prepared by electro-deposition with sodium 4-styrene sulfonate(PSS)solution.The effect of PSS concentration on membrane properties was studied.With the increase of PSS concentration,the hydrophilicity,negative charge density and antifouling ability of surface of PSS modified membranes increased.When the concentration of PSS was 1.5g/L,the transformation time of the modified membrane was the longest,so the most suitable concentration was 1.5 g/L.Secondly,a mixed solution of Ti O2 and PSS was used to modify the AEMs.With the increase of Ti O2 concentration,the hydrophilicity,negative charge density and antifouling ability of Ti O2-PSS modified membranes increased.When the concentration of Ti O2 was 5 g/L,the transition time of Ti O2-PSS modified membranes was longest.At the same time,the results of membrane fouling cycle experiments showed that the hydrophilicity of Ti O2-PSS modified membranes can be improved by ultraviolet irradiation,and ultraviolet irradiation was beneficial to the decomposition of organic foulants,which gave the Ti O2-PSS modified membranes a certain self-cleaning property.Finally,the AEMs were modified with a mixed solution of dopamine(DA)and PSS.The results showed that the smoothness,hydrophilicity and negative charge density of surface of the PDA-PSS modified membranes were improved by the electro-deposition process.When the concentration of DA was 0.375 g/L,the PDA-PSS modified membrane has the longest transition time,indicating the best antifouling ability.A layer of Ti O2 was deposited on the surface of the PDA-PSS modified membranes to obtain PDA-PSS/Ti O2 modified membranes.The hydrophilicity of PDA-PSS/Ti O2 modified membranes was greatly improved with Ti O2 deposition and the contact angle decreased from 78.4° to 14.8°.The negative charge density of the surface of the PDA-PSS/Ti O2 modified membranes was improved compared with the pristine AEMs.The transition time of the PDA-PSS/Ti O2 modified membranes was the longest with 0.75 g/L of DA.Moreover,the results of membrane fouling experiments showed that PDA-PSS/Ti O2 modified membrane had good antifouling stability.