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

TLDR

Effective, sustainable solutions for oily water cleanup and separation are urgently needed. This study introduces a fully inorganic Cu₃(PO₄)₂ nanosheet‑wrapped mesh membrane. The intersected nanosheet architecture and Cu₃(PO₄)₂ hydration give the membrane superhydrophilicity, underwater anti‑oil‑fouling and antibio‑fouling, achieving underwater oil contact angles >158° and negligible adhesive force even under a 400 µN preload. The membrane demonstrates high chemical, thermal, and salt tolerance, delivering ~4000 L m⁻² h⁻¹ permeate flux with oil content <2 ppm over 2000 L of crude oil/water in cross‑flow filtration, indicating large capacity, long‑term stability, and practical scalability.

Abstract

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.