Cupric Phosphate Nanosheets-Wrapped Inorganic Membranes with Superhydrophilic and Outstanding Anticrude Oil-Fouling Property for Oil/Water Separation.

Developing an effective and sustainable solution for cleaning up or separating oily water is highly desired. In this work, we report a completely inorganic mesh membrane made up of cupric phosphate (Cu3(PO4)2) in a special intersected nanosheets-constructed structure. Combing the hierarchical structure with strong hydration ability of Cu3(PO4)2, the nanosheets-wrapped membrane exhibits a superior superhydrophilic and underwater anti-oil-fouling and antibio-fouling property for efficient oil/water separation to various viscous oils such as heavy diesel oil, light crude oil, and even heavy crude oil with underwater oil contact angles (CAs) all above 158° and nearly zero underwater oil adhesive force even when a large preload force of up to 400 μN was applied on the oil droplet. Simultaneously, the membrane exhibits a high chemical and thermal stability and outstanding salt tolerance. Continuous separation operated on a cross-flow filtration apparatus demonstrates a large separation capacity and long-term stability of the membrane during treating a 2000 L crude oil/water mixture with constantly stable permeating flux of ∼4000 L/m2 h and oil content in the filtrate below 2 ppm. The excellent anti-oil-fouling property, high separation capacity, and easily scaled-up preparation process of the membrane show great potential for practical application in treating oily wastewater.