Surface Segregation‐Induced Superwetting Separation Membranes with Hierarchical Surface Structures and Internalized Gel Networks

Abstract

The porous polymeric membranes prepared by conventional nonsolvent‐induced phase separation (NIPS) suffer from notorious fouling pollution during oil/water separation. Herein, an improved one‐step NIPS strategy is proposed to fabricate anti‐fouling polyethersulfone (PES) based membranes that bear hierarchically spherical structures on the interface and an internalized gel network. More specifically, the hydrogen bonding between hydrophilic additives of polyvinylpyrrolidone (PVP) and tannic acid (TA), as well as Fe3+‐TA coordination interaction are orchestrated to modulate their surface segregation behaviors during NIPS, leading to in situ generation of the interfacial assembled nanospheres and embedded gel networks in the PES matrix. Thanks to the synergistic effect of these dual antifouling barriers, the optimized membrane exhibits super‐hydrophilic/underwater super‐oleophobic properties, and displays high efficiency as well as good recyclability in separating surfactant stabilized oil‐in‐water emulsions. In addition, this improved NIPS methodology allows dip coating of various porous substrates to separate diverse oil/water mixtures, which also exhibits good anti‐fouling ability. Basically, this study will provide new insights for design of anti‐pollution oil/water separation materials by the phase inversion method.

A Simple Poly(Vinyl Sulfonate) Coating for All‐Purpose, Self‐Cleaning Applications: Molecular Packing Density–Defined Surface Superhydrophilicity

“…Nowadays the vast majority of oil/water separation membranes rely on nanostructures embossed on their surfaces to achieve superhydrophilicity, which, however, require wetting of the membrane surfaces with water to inhibit the infusion of oil into the nanostructures prior to oil/water separation. [46][47][48][49] In this scenario, anti-grease, superhydrophilic coatings enable oil/water separation membranes to operate without the prior water wetting, [11][12][13] which will be of technical benefit to practical applications for instance rapid and effective clean-up of oil spill from seawater (Figure 6c). In order to challenge the anti-grease performance in the application of oil/water separation, here we coated conventional stainless steel meshes with PVS n -CSs and utilized to skim oil from water according to the protocol reported in previous studies.…”

Preparation of a PVDF–PDA–DETA@PVP@HNT membrane for high efficiency oil–water emulsion separation

“…[11][12][13][14][15] Polymer materials commonly used for membrane separation include polyacrylonitrile (PAN), polyethersulfone (PES), polypropylene (PP), polyvinylidene fluoride (PVDF), and so on. [16][17][18][19][20] Among them, PVDF is one of the most popular and important polymers in industrial applications and research studies. PVDF membranes are widely used in microfiltration, ultrafiltration and wastewater treatment processes due to their excellent properties, including high thermal stability, mechanical stability and chemical resistance.…”

Rapid Construction of Caffeic Acid/p-Phenylenediamine Antifouling Hydrophilic Coating on a PVDF Membrane for Emulsion Separation

“…In recent years, oil pollution has become a serious problem worldwide, which caused immense damage to human society and the ecological system. , Oily wastewater has a wide range of concentrations, with oil concentrations ranging from 10 to 200,000 mg/L . The US Environmental Protection Agency limits oil and gas industry emissions of oily wastewater to 42 mg/L per day, while in China, the limit is 10 mg/L .…”