Modifying polymeric membrane with expansible microgels containing silver nanoparticles: regulating the catalytic activity by forced convection in three-dimensional network

Noble metal nanoparticles (NMNPs) are crucial for catalytic processes, but their recycling and aggregation present challenges. Immobilizing NMNPs on substrates often reduces their catalytic activity due to hindered diffusion and decreased surface area. This study presents a novel approach using silver (N-Isopropylacrylamide Co methyl acrylic acid) (Ag@PNM) nanoparticles, characterized by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), dynamic light scattering transmission (DLS), transmission electron microscopy (TEM) and UV–visible spectroscopy. A catalytic membrane with silver nanoparticles (Ag NPs) embedded in a three-dimensional (3D) network of hybrid microgels was fabricated. The microgels are filtered into a microporous membrane and expanded to secure the Ag NPs, enhancing catalytic efficiency for 4-nitrophenol reduction through improved mass transfer and exposure of the nanoparticles. The membrane shows high stability and performance, with a turnover frequency of 77.5 h⁻¹ and an apparent rate constant (k_app) of 0.15 s⁻¹. Additionally, the PES/Ag@PNM membrane demonstrated effective reduction of 4-nitrophenol. The straightforward synthesis and stability of this approach make it a promising and cost-effective solution for industrial applications.