Multifunctional PDMS polyHIPE filters for oil-water separation and antibacterial activity

Herein, we present the fabrication of multifunctional polydimethylsiloxane (PDMS) foams with antibacterial, hydrophilic, and underwater superoleophobic properties for the separation of oil-water mixtures and simultaneous water disinfection. The PDMS foams, prepared following the high internal phase emulsion templating method, exhibit a porous interconnected structure and were further functionalized with a polydopamine (PDA) layer and in-situ grown silver nanoparticles (Ag NPs) upon successive dipping processes in dopamine and silver nitrate solutions. We demonstrate the successful use of the developed foams as 3D filters for the gravity-driven separation of oil-water mixtures and the subsequent disinfection of the filtered water. The flow rate of oil-water mixtures is strongly correlated to the in-situ grown Ag NPs density present on the foams, in contrary to the oil rejection efficiency, which is above 99.99% in all the studied cases. In fact, the flow rate values increase with the increasing density of the in-situ formed Ag NPs starting from 1937.7 ± 580.4 L m−2 h−1 for the foam without Ag NPs and reaching 4043.0 ± 710.7 L m−2 h−1 for the foam with the highest amount of NPs. Taking the latter as an example, we prove that the foams can be used for several filtration cycles without any modification of their oil rejection efficiency. In addition to efficient oil-water separation, the foams have antibacterial properties and are able to disinfect the permeate. The simple preparation method, effective gravity-driven filtration, robust nature, and antibacterial capability make the herein engineered multifunctional foams promising for highly efficient filtration processes.