Silver nanoparticles supported on polyethylene glycol/cellulose acetate ultrafiltration membranes: preparation and characterization of composite

In this research work, silver nanoparticles/polyethylene glycol/cellulose acetate ultrafiltration (Ag-NPs/PEG/CA UF) composite membranes were synthesized and characterized. The Ag-NPs were embedded in the polymer matrix by two methods: in situ and ex situ; varying the type of solvent used (dimethylformamide, DMF; or N-methyl-2-pyrrolidone, NMP). The Ag-NPs used in the ex situ method were synthesized by a green chemistry reduction method. The composite membranes were characterized by Fourier transform infrared spectroscopy with attenuated total reflection (FTIR-ATR), scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS), and thermogravimetric analysis-derivative thermogravimetric analysis (TGA-DTG); the molecular weight cut-off and permeability were also determined. Moreover, the antibacterial efficiency of the composite membranes was measured against bacteria like Escherichia coli and Staphylococcus aureus. By FTIR-ATR analysis it was possible to observe that the Ag-NPs embedded in membranes changed the membrane morphology. The SEM-EDS analysis showed that the in situ composite membranes have good dispersity of Ag-NPs, DMF FB being the most densely populated obtained. By another hand, the ex situ DMF NP composite membrane presented the highest amount of silver signals per unit area (µm2). The permeability of the membrane was affected by the presence of the Ag-NPs; the DMF NP composite membrane had the highest permeate flow, while DMF FB had the highest antibacterial activity.