Integration of membrane filtration and photoelectrocatalysis on g-C3N4/CNTs/Al2O3 membrane with visible-light response for enhanced water treatment

Abstract

Coupling membrane filtration with photocatalysis provides a promising way to improve the membrane performance for water treatment. However, the quick recombination of photogenerated electron-holes and poor visible-light response limit the performance of photocatalytic membrane. Herein, a g-C3N4/CNTs/Al2O3 membrane was prepared through sequentially coating carbon nanotubes (CNTs) layer with high electroconductivity and g-C3N4 layer with good visible-light response on Al2O3 membrane support. When a positive voltage was applied on the CNTs layer, photogenerated electrons in the visible light irradiated g-C3N4 layer could be drawn away and separated from the holes, thus rendering membrane with photoelectrocatalytic function and largely improved performance. The membrane filtration integrated with photoelectrocatalysis (PECM) showed enhanced phenol removal with the increase of voltage supply. At 1.0V, the PECM process displayed photoelectric synergetic effect, whose phenol removal efficiency was 2.7, 2.0 and 10.1 times higher than that of filtration with visible light irradiation (PCM), filtration with 1.0V and filtration alone, respectively. The PECM also presented improved antifouling capability during the removal of natural organic matters. Its stable permeability (measured at 1.5V) was 1.4 and 3.0 times higher than that of PCM and filtration alone, respectively. Significantly, the PECM also displays outstanding capability in surface water treatment.