Development and characterization of hybrid membranes based on an organic matrix modified with silanes for metal separation

New hybrid membranes for metal ion transport were synthesized with the aim of improving mechanical and chemical stabilities, mean lifetime and loss of carrier. Hybrid organic–inorganic materials present several advantages with respect to organic and inorganic materials considered independently. Organic–matrix membranes usually have limitations related to chemical and thermal stabilities while organosilicone materials may present serious difficulties for film formation. The new membranes proposed here are based on a mixture of organic (cellulose triacetate, CTA) and organosilicone materials (dichlorodimethylsilane and tetraethoxysilane, DDMS and TEOS, respectively) as membrane support. Membrane preparation was optimized varying the amount of metal carrier (bis(2-ethyl hexyl phosphoric acid), D2EHPA) and plasticizer (2-nitrophenyloctyl ether, NPOE and/or tris(2-butoxyethyl)phosphate), TBEP). Total Reflection Infrared Spectroscopy, Scanning Electron Microscopy, Thermogravimetric Analysis, 29Si Nuclear Magnetic Resonance and X-Ray Diffraction were used to characterize the hybrid membranes and to correlate structural properties with permeability values for zinc metal ions.