Electrically conductive TiO2/CB/PVDF membranes for synchronous cross-flow filtration and solar photoelectrocatalysis

Combining photocatalysis (PC) and membrane filtration (MF) has emerged as an attractive technology for water purification, however, the water purification efficiency and membrane fouling are still challenging. Herein, we report a novel photoelectrocatalytic (PEC) membrane mediated by a ternary polyvinylidene fluoride (PVDF)-carbon black (CB)-TiO2 composite conductive membrane synthesized by a phase inversion method assisted by the mixed surfactants of polyvinylpyrrolidone (PVP) and sodium dodecyl sulfate (SDS). The resultant electrically conductive TiO2/CB/PVDF membrane features a homogeneous surface with obvious pore size of 20-150 nm, a thickness-116 mu m, and an average resistivity as low as-3.165 omega center dot m. The cooperation of PVP and SDS sur-factants dramatically improves the organic-inorganic interactions and thus eventually enhances the porosity, stability of porous structure, mechanical stability, and conductivity and electrochemical properties of the hybrid membrane. Upon the solvent evaperation of the wellblended casting solution and the phase inversion, TiO2/CB preferentially exist on the surface of PVDF membrane, enabling the efficient PEC degradation of organic pol-lutants. The synergistic coupling of TiO2 and CB in PVDF membrane results in efficient PEC properties with bi-functional membrane antifouling and enhanced water purification in azo dyes decolorization under the sta-tionary mode and in our lab-made continuous cross-flow PEC system, superior to those by photocatalysis and electrocatalysis. The developed synchronous MF and PEC system mediated by the conductive TiO2/CB/PVDF membrane proves to a feasible route to improving the self-cleaning properties of the polymer membrane while simultaneously increasing the water decontaminating efficiency.

Automated summary

Combining photocatalysis and membrane filtration, a novel photoelectrocatalytic membrane has been developed for efficient water purification. The PVDF-carbon black-TiO2 composite conductive membrane, synthesized by a phase inversion method assisted by PVP and SDS surfactants, exhibits a homogeneous surface with pore size of 20-150 nm, a thickness of 116 μm, and a low resistivity of -3.165 Ω·m. The TiO2/CB/PVDF membrane enables efficient PEC degradation of organic pollutants through the cooperation of PVP and SDS surfactants.