Mixed-matrix membranes based on polyurethane containing nanohydroxyapatite and its potential applications

ABSTRACT In this study, new asymmetric polyurethane (PU) mixed‐matrix membranes with different nanohydroxyapatite loadings were prepared via a dry–wet phase inversion method by the dispersion of hydroxyapatite (HA) nanoparticles in the PU matrix. The HA nanopowder was obtained by a wet chemical precipitation method; it showed an average crystallite size of 58.3 nm, a specific surface area of 261 m2/g, and a pore size of about 1.6 nm. The effects of the HA loading (10–50 wt %) on the PU membrane characteristics were studied. The scanning electron microscopy images revealed that the HA nanoparticles were well dispersed enough in the PU matrix. The average pore size in the top layer and porosity of the membranes slowly decreased, whereas the hydrophilicity and water permeability increased with increasing content of HA. The evaluation of the nanofiltration performance was performed by investigation of the NaCl rejection. The composite membranes had a higher salt‐removal capacity than the unfilled PU membrane. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41813.