Superwetting Polypropylene Nonwoven Fabrics Modified by a Catechol-Based Biomimetic Strategy for Oil/Water Separation

The superwetting membrane with superhydrophilic/underwater superoleophobic properties is one of the ideal materials for treating oily wastewater. We combined a catechol/silane biomimetic composite coating system and a metal-phenolic network structure to co-deposit a dopamine-like superhydrophilic coating on polypropylene nonwoven fabrics. The modified fabric separated oil–water mixtures with a filtration efficiency of up to 99%. Besides, the as-prepared material has the property of nonstick oil underwater and outstanding stability. After 30 cycles of separation tests, the pure water flux can be restored to 94.5% of the initial value after rinsing with deionized water. It maintained underwater superoleophobic properties after being immersed in a harsh environment of pH 1 or 13 for 1 h. Compared with dopamine hydrophilic modification, this method was more economical and time-consuming and could fabricate a full-scale separation material.