Functionalization of the surface of ceramic membranes with 3-mercaptopropyl groups using the sol-gel method

Tubular ceramic membranes based on α-Al₂O₃ were functionalized with 3-mercaptopropyl groups using the sol-gel method. The formation of the polysiloxane layer on the inner surface of the membranes was confirmed by SEM images and FTIR spectroscopy data. The functionalized membranes (identically to the original one) retain the high performance typical of highly efficient microfiltration membranes (320-690 L/m² h); however, they can be used to remove silver(I) ions from water due to the formation of complexes between thiol groups of the active layer and silver(I) ions. It was also shown that the decreasing concentration of functionalizing sol produces a thinner surface polysiloxane layer with more active sites available for the sorption of Ag⁺ ions. Thus, fourfold dilution of the starting sol results in a tenfold increase in the sorption of Ag⁺ ions calculated per mass unit of the functionalizing layer (from 23 to 203 mg/g).