Exploring the Potential of Perovskite Structured SrTiO3 Ceramics Nanoparticles for Developing SrTiO3 Ceramics-Decorated Advanced Super-Wettable and Photocatalytic Self-Cleaning Membranes and Their Applications

Abstract

There is a huge potential in developing robust, highly stable, and covalently crosslinked ceramics-decorated membranes that can be efficiently used for the treatment of oil-contaminated water. Hence, the current work was focused on developing a photo-active strontium titanate (SrTiO₃) perovskite ceramics decorated highly stable membrane with photocatalytic self-cleaning, superoleophobic underwater and superhydrophilic in air features. The SrTiO₃ perovskite structured ceramics decorated the active layer of the membranes through interfacial polymerization on a polyvinylidene difluoride (PVDF) ultrafiltration (UF) support. For the sake of photoactive SrTiO₃ ceramics nanoparticles to take part in the interfacial polymerization, the SrTiO₃ ceramics nanoparticles were functionalized with amino silane using 3-aminopropyltriethoxysilane yielding amino-functionalize-SrTiO₃ (F-SrTiO₃). Ethylenediamine (EDA) was used as an additional amine for ensuring the suitable cross-linking of the polyamide (PA) network where isophthaloyl chloride (IPC) was used as a crosslinker. The resultant F-SrTiO₃/PA@PVDF membrane was thoroughly investigated through several membrane characterization techniques confirming the existence of all the components in the membrane structure. When applied for separating the emulsified and surfactant stabilized oil from water, the F-SrTiO₃/PA@PVDF membrane showed excellent separation efficiency reaching >99% for an emulsion of 200 ppm with a permeance of 56 L m^-2 h^-1 bar^-1. Moreover, the membrane showed an underwater superoleophobic (θ_{O, W} = 159.9^o) nature owing to the presence of amide linkages and superhydrophilic F-SrTiO₃ nanoparticles. These features lowered the evidence of membrane fouling and the photocatalytic self-cleaning potential of F-SrTiO₃ resulted in removing the foulants from the membrane surface with a flux recovery of 95% while keeping the separation efficiency intact. Hence, the current approach of covalently incorporating the photocatalytic, superhydrophilic F-SrTiO₃ in the membrane active layer proved to be robust and can be readily scaled up and applied in real-life filtration conditions.