Engineering of ultrafine polydopamine nanoparticles in-situ assembling on polyketone substrate for highly-efficient oil-water emulsions separation

Environmental issues caused by oily pollutants is one of the most severe challenges for the global ecosystem and public health. To develop the advanced membrane materials with superior antifouling property is urgently needed for highly efficient oily wastewater purification. In this study, an ultrathin polydopamine layer with a controllable thickness of similar to 90 nm was decorated onto a porous polyketone substrate via an extremely simple and scalable surface modification process. The ammonia initiator facilitated the ultrafine polydopamine nano particles (with its size about 30 nm) in-situ assembling. Benefiting from the ultrathin surface modification, the resultant polydopamine decorated polyketone (PDA-d-PK) membrane performed ultrahigh water permeance up to 11600 L m(-2) h(-1) bar(-1). This membrane also exhibited a superior oily emulsions separation property with remarkably high permeance up to 8300-10600 L m(-2) h(-1) bar(-1), and high rejection ratio more than 99.9% against various oily phases, including hexane, hexadecane, petroleum ether, and soybean oil. The hierarchical nanosphere-like polydopamine layer with superhydrophilicity/underwater superoleophobicity also endowed the PDA-d-PK membrane with an excellent antifouling performance against the oily emulsions containing surfactant, protein, and natural organic material. The PDA-d-PK membrane also featured a superior tolerance and durability under challenging conditions of salty, strong acid/alkali solutions, and a variety of organic solvents. This work provides an insight into the facile preparation of an ultrathin polydopamine membrane with simultaneous enhancement in separation and antifouling properties for highly-efficient oil-water emulsions separation.