Facile preparation of ultralong polypyrrole nanowires-coated membrane for switchable emulsions separation and dyes adsorption

Herein, an ultralong polypyrrole nanowires-coated stainless steel mesh (PPy@SSM) was successfully prepared to cope with the on-demand separation of oil/water emulsions as well as dyes adsorption via electrodeposition. The as-prepared PPy@SSM could be switched from superhydrophilic to hydrophobic under electric field for at least 50 times. Benefiting from the high porosity and its selective wettability, the PPy@SSM exhibited excellent separation efficiency of up to 99.88 % and high filtration flux of up to 2984 L m−2 h−1 for both oil-in-water and water-in-oil emulsions, even for the high viscous crude oil-in-water emulsion. Thanks to the surface charge, abundant aromatic rings of PPy, and porous structure, PPy@SSM also achieved selective adsorption of cationic or anionic dyes with high efficiency (up to 99.28 %) under diverse pH conditions. Moreover, the PPy@SSM also displayed a strong chemical resistance and mechanical stability under harsh conditions such as extreme temperature, corrosive environments, and various friction tests. Combined with a simple and environmental-friendly fabrication process, the high-performance membrane PPy@SSM has promising applications in the separation of oil/water emulsions and the adsorption of dyes.