A novel sequential hexafluoroalcohol (SHFA) membrane composed of a non-substituted aromatic polyamide under-layer and a hexafluoroalcohol-substituted aromatic polyamide top-layer, for the purpose of achieving improved performance in reverse osmosis (RO) desalination, is the major subject of this research study. At 2000 parts per million (ppm) salt solution, the SHFA membrane outperformed the reference (REF) membrane, which was formed by a conventional RO membrane process, in terms of salt rejection. A salt rejection of greater than 99.5% and a flux of greater than 50 liters/m2/h (LMH) were obtained at 400 psi and 25oC operating conditions. Either 2 or 3 min HFA-MDA reaction time could be used to process the SHFA membrane to achieve this performance. Results from the analyses of the REF membrane and SHFA membrane using transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), atomic force microscopy (AFM), and a contact angle measurement tool were used to compare the two membranes\u27 surface morphology.
In addition to the SHFA membrane, works involving incorporation of nanocomposite particles onto the RO membranes for performance improvement are covered. The latest findings from this research led to the introduction of a porous nanoparticle (PNP) membrane whose low particle loadings (ranges from 0.01% to 0.05% weight-to-volume) were found to enhance water flux while retaining high salt rejection
