Bio-inspired magnetic superhydrophobic PU-PDA-Fe3O4-Ag for effective oil-water separation and its antibacterial activity

In this work, a feasible collaborative design method for preparing magnetic superhydrophobic PU-PDA-Fe3O4-Ag sponge was proposed. Inspired by mussels, polydopamine (PDA) was used as a bio-glue to adhere Fe3O4, Ag nanoparticles and octadecylamine to the skeleton of the PU sponge. Under the synergistic effect, Fe3O4, Ag nanoparticles and octadecylamine endowed the PU sponge with magnetic response properties, antibacterial activity and superhydrophobic surface. The obtained superhydrophobic PU-PDA-Fe3O4-Ag sponge showed high absorption capacity for various oils and organic solvents with up to 22.9-52.0 times its own weight, which possessed a comparable or relatively high adsorption capacity compared with other reported superhydrophobic PU sponges. Due to the magnetic properties and good elasticity of the obtained PU sponge, the adsorbed oil can be quickly circulated through magnetic recovery and mechanical extrusion. After 20 absorption-desorption cycles, the adsorption capacity of the modified sponge remained above 90.9 % of the initial value, and under negative pressure, the sponge can be used as a filter for continuous separation of light oil and heavy oil from water. In addition, the surface-modified PU sponge also shows excellent oil-in-water emulsion degreasing performance, and the separation efficiency of toluene in water can reach 96.4%. Interestingly, the resulting PU sponges exhibited antibacterial activity with the action of Ag nanoparticles, indicating their potential environmental adaptability and durability in bacteria-contaminated oil/water mixture. The multifunctional characteristics of the modified polyurethane sponge prepared in this study have great potential for the practical application of oil spill treatment.