Ultralong hydroxyapatite nanowire-incorporated PVDF mixed-matrix membranes for enhanced forward osmosis performance

A simple and novel treatment strategy was developed to fabricate poly (vinylidene fluoride) (PVDF)-based forward osmosis mixed matrix membranes (MMM) with enhanced desalination performance. The proposed approach focuses on improving the surface properties of PVDF membranes through incorporation of ultralong hydroxyapatite (UHA) nanowires as hydrophilic inorganic additives. PVDF and UHA possess excellent mechanical strength, thermal stability, and chemical resistance, making them promising materials for membrane fabrication. However, the intrinsic hydrophobicity of PVDF limits water permeability and flux, reducing membrane efficiency and increasing operational costs. Therefore, UHA nanowires were incorporated into the PVDF matrix to enhance membrane hydrophilicity and separation performance. The fabricated membranes were comprehensively characterized using X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) to investigate their structural, chemical, and morphological properties. Membrane performance was evaluated through forward osmosis desalination experiments by measuring water flux and reverse salt flux. The pristine PVDF membrane exhibited a water flux of 2.1 LMH, while the modified PVDF/UHA membrane achieved 3.6 LMH, corresponding to approximately a 70% enhancement in water permeability. In addition, the modified membranes demonstrated improved antifouling behavior and operational stability. The obtained results indicate that incorporation of UHA nanowires effectively improves membrane hydrophilicity and desalination performance, highlighting the strong potential of PVDF/UHA composite membranes for forward osmosis desalination and wastewater treatment applications.