Lauric acid surface modified Co2+-ZnO@SSM composite membrane: Photocatalytic degradation of MB and oil/water separation for removal of organic pollutants

The stainless steel wire mesh supported Co 2+ -doped ZnO with lauric acid modification (LA/Co 2+ -ZnO@SSM) was prepared through hydrothermal method for dual-functional oil/water separation performance and high photocatalytic activity. By changing the immersing time of LA, the surface polarity of the LA/Co 2+ -ZnO@SSM composite membrane could be efficiently adjusted from hydrophilic to hydrophobic. The superhydrophobicity of LA/Co 2+ -ZnO@SSM was achieved after LA immersing 120 min, and the WAC value reached as 156.6 ± 3.0°. In different oil/water mixture systems, the LA/Co 2+ -ZnO@SSM composite membrane exhibited excellent oil/water separation ability and separation throughput, and the separation efficiency still remained above 90 % after 10-cycle separation. Meanwhile, the LA/Co 2+ -ZnO@SSM composite also maintained an excellent photocatalytic activity, and the photocatalytic efficiency for methylene blue degradation reached 90 %. Even in the solution of complex organics and oil, the photocatalytic degradation efficiency was still above 75 %. In addition, LA/Co 2+ -ZnO@SSM composite membrane also showed a low adhesion, good flexibility and anti-pressure ability. All results indicated that the dual-functional LA/Co 2+ -ZnO@SSM composite membrane with visible light-driven photocatalysis and oil/water separation performance could be used for practical complex wastewater as a novel purification strategy.