Layer-by-Layer Nanoassembly of Cu(OH)2 Multilayer Membranes for Nanofiltration

A facile way to prepare Cu(OH)2 inorganic nanofiltration membranes with neatly arranged multilayers has been developed based on the reaction of a sodium hydroxide solution and a copper ammonia solution at the liquid–liquid interfaces. The effects of the concentration, temperature, and time of the liquid–liquid reaction on membrane structure and pore sizes were studied by SEM, TEM, and X-ray diffraction. The growth mechanism of the membrane was discussed and the formation process model was proposed. It was found that the reaction temperature was a key factor in obtaining a Cu(OH)2 monolayer, and this could be used to adjust the thickness and pore size of the monolayer. The as-prepared Cu(OH)2 membranes exhibited excellent filtration performance with the pure water fluxes of 156.2 L·m−2 h−1 bar−1 and retention rates of 100% for methylene blue (50 ppm) at a pressure of 0.1 MPa. This successfully opens up a new method of synthesizing multilayer nanoarrays’ Cu(OH)2 structure for nanofiltration.