Preparation of Janus membrane based on biomimetic polydopamine interface regulation and superhydrophobic attapulgite spraying for on-demand oil-water emulsion separation

Here, we report a Janus membrane constructed using a sustainable regenerated cellulose (RC) membrane as matrix, based on biomimetic polydopamine (PDA) interface regulation and superhydrophobic attapulgite (SOATP) spraying. The dual-action PDA was reasonably interfacially-regulated by high temperature-induced self-polymerization to construct a superhydrophilic surface with PDA layer/particle hierarchical structures, which strengthened the interfacial interactions between the organic RC substrate and inorganic SOATP. Subsequently, SOATP was sprayed on the bottom surface of membrane via a simple spraying method to obtain a superhydrophobic surface. The resulting RC@PDA/SOATP Janus membrane exhibited a superhydrophilic top surface and superhydrophobic bottom surface, with excellent separation efficiency (>99%) and acceptable permeation flux toward different types of emulsions. The membrane also showed good renewability, excellent environmental durability and structural stability. The facile and versatile interface regulation and spraying techniques, as well as the environmentally friendly and economical raw materials, were used, which makes the Janus membrane a promising solution for a range of applications in the field of oil-water separation.