NH4HCO3 as additive for fabrication of thin film nanocomposite membrane with enhanced permeability.

During interfacial polymerization, the in situ growth of nanobubbles can exist between the support layer and the separation layer of the membrane, which changes the microstructure of the membrane and improves its performance. The incorporation of R812s SiO₂ in the preparation of the mixed matrix nanofiltration membrane increases the surface interface pores, thereby improving the flux. In this study, NH₄HCO₃ foaming agent was introduced into the aqueous phase of the R812s SiO₂ nanofiltration membrane to react with the byproduct HCl generated during the interface process, thus generating nanobubbles that exist between the support layer and the separation layer. The surface of the membrane was characterized by related instruments. It was found that the addition of NH₄HCO₃ generates a large number of nanobubbles, causing significant changes to the membrane surface, and resulting in increased protrusions and pore size, greatly improving membrane flux while slightly reducing the rejection of sodium sulfate. [ABSTRACT FROM AUTHOR]