Robust nanoparticles growth in the interior of porous sponges for efficient dye adsorption and emulsion separation

Emulsified oils and dye contaminants already pose a huge threat to global ecosystems and human health. It is a significant research topic to develop efficient, rapid, versatile methods for emulsion separation and dye adsorption. The membrane material modified with common methods only modified the outer surface of the membrane, while the interior is hardly fully decorated. In this investigation, a solvent exchange method was used to in situ grow nanoparticles in the interior of a porous sponge. These nanoparticles were obtained with polyethyleneimine, gallic acid, and tannic acid via Michael addition and Schiff base reaction. The prepared nanoparticle-coated sponges provided efficient separation of dyes, emulsions, and complex contaminants. The separation efficiency of the dye reached 99.49%, and the separation efficiency of the emulsion was as high as 99.87% with a flux of 11140.3 L m^-2 h^-1. Furthermore, the maximum adsorption capacity reached 486.8 mg g^-1 for cationic dyes and 182.1 mg g^-1 for anionic dyes. More importantly, the nanoparticles were highly robust on the surface of the porous sponge, and the modified sponge could have long-term applications in hazardous environments. Overall, it is envisioned that the nanoparticles-modified porous sponge exhibited considerable potential for emulsion and dye wastewater treatment.