To improve the separation efficiency and decrease fouling of the membranes used in oil-in-water emulsions separation, a superhydrophilic and underwater superoleophobic TiO 2 /Al 2 O 3 composite membrane with ultra low oil adhesion was designed. TiO 2 nanorod arrays were prepared on Al 2 O 3 porous ceramic membrane surface by simple magnetron sputtering and hydrothermal oxidation. The microstructure and surface photosensitivity of TiO 2 nanorod array-coated ceramic membrane can effectively increase the efficiency of oil-water separation and reduce the degree of surface fouling. The layer of TiO 2 nanorod arrays not only reduced the pore size of traditional ceramic membrane (enhanced sieving effect of porous structures) but also endowed its superhydrophilicity (enhanced flux) and underwater superoleophobicity (enhanced oil/water selectivity and antifouling). Based on the superhydrophilicity (water contact angle (WCA) of 0°) and underwater superoleophobicity (oil contact angle (OCA) higher than 150°) of ceramic membrane, oil droplets were blocked by the membrane (oil-water separation efficiency 99.1% under gravity) and water will pass (flux is maintained at 41.8 L/(m 2 h) under gravity). It also has excellent anti-fouling ability due to the ultra-low oil adhesion force (0.084 mN) of the TiO 2 nanorod array-coating after UV irradiation. These features, combined with energy-saving, low-cost and easy-to-scale manufacturing schemes will be of great versatility and practicality in environmental rehabilitation and wastewater purification.
Hu Xuebing,Yu Yun,Ren Shuang,Lin Na,Wang Yongqing,Zhou Jianer
To achieve superior separation performance in the phenol aqueous solutions treatment, a novel graphene oxide/Al 2 O 3 composite membrane was prepared by a spin coating process. The microstructure measurement shows that the composite membrane has a multilayer structure and graphene oxide has been tightly coated on the surface of the Al 2 O 3 membrane interlayer homogeneously. During the treatment of phenol aqueous solutions, the permeation flux and phenol rejection of the composite membrane were investigated. The results show the permeation flux of the membrane is about 1.153 L m −2 h −1 bar −1 and the phenol rejection of the membrane increases to 99.9% when the phenol concentration is 0.01 g L −1 . The high phenol rejection of the composite membrane is mainly attributed to the physical sieving, the solution–diffusion effect and the hydrophobic nature of graphene oxide. All these results indicate the GO/Al 2 O 3 composite membrane is a suitable material for the removal of phenol from aqueous solutions in environmental pollution management.