High-performance CrN tight ultrafiltration membranes prepared by in situ gas–solid catalytic reaction

Abstract

To expand the industrial application of membranes, high-performance CrN tight ultrafiltration membranes (UF) were prepared by in situ gas–solid reaction using Cr2O3 as a nanoprecursor and TiO2 as a nitriding catalyst in ammonia atmosphere. The phase composition and microstructure of CrN UF membranes were characterized by X-ray diffraction and field-emission scanning electron microscopy with energy-dispersive X-ray spectroscopy. The effects of TiO2 and sintering parameters on the crystalline phase and pore size of CrN UF membranes were investigated. The results identified Ti4+ as a key factor influencing the transformation of the Cr2O3 phase into the CrN phase. The as-prepared CrN membranes exhibited enhanced hydrophilicity, no cracks or pinholes, water flux of 121 L·m−2h−1 bar−1, and a molecular weight cut-off of 1500 Da. The membranes also had retention rates of 100% for methyl blue (50 ppm) and 90% for methylene blue (50 ppm), which almost remained constant under repeated use.