Novel use for metal nanowires – synthesis, characterization and application of nickel and silver nanowires in the process of ethanol dehydration via pervaporation

Abstract

In order to improve the separation properties of water/ethanol mixture, silver (Ag-NWs) and nickel nanowires (Ni-NWs) were used as a filler for alginate membranes. An effective separation of water from ethanol molecules was demonstrated using the unusual shape, size, quantity and properties of the nanowires. The synthesized nanowires were obtained by the polyol process (silver) and the reduction with hydrazine in an alkaline environment intensified by the action of an external magnetic field (nickel). To characterize the obtained nanowires and membranes, SEM, TEM, SQUID magnetometer and EDS measurements were performed. Moreover, the hydrophilicity of investigated membranes was measured using contact angle and degree of swelling. The explanation of the phenomena occurring during the permeation of water and ethanol molecules through the investigated membranes was performed according to the random walks simulation. The study shows that the efficiency of the process is related to the structure and hydrophilicity of the membranes, the formation of networks that facilitate the transport in the membrane and magnetic properties of the nickel nanowires. The highest value of the separation coefficient was obtained for the membrane filled with 50 mg (5 ml) of nanowires. In this case, flux and separation coefficient ​​were equal to 1.1 kg·m−2·h−1 and 878 for membranes with silver and 1.6 kg·m−2·h−1 and 1415 for nickel nanowires, respectively.