Fine-intercalated MOF nanoarray pervaporation membranes for high-efficiency photothermal desalination

Conventional blending of inorganic nanomaterials in polymer matrices for pervaporation (PV) desalination often encounters poor interfacial compatibility and nanoparticle agglomeration, which compromise membrane performance. Simultaneously, the energy-intensive nature of conventional thermal crosslinking in polyvinyl alcohol (PVA) membrane fabrication and pervaporation process poses a significant challenge for sustainable application. Inspired by the prong setting of a diamond ring, this study introduces a hierarchically structured membrane fabricated through a sequential spray-engineered approach. Initially, a spray-phase inversion process enables the in-situ anchoring of UiO-66 nanoparticles into a poly( m -phenylene isophthalamide) (PMIA) substrate, creating an interlocked nanoarray interlayer. Subsequently, a PVA-GO separation layer is sprayed onto this functionalized nanocomposite substrate. Leveraging the thermal insulation effect of the fine-integrated UiO-66 nanoarray, the PVA-GO layer subsequently undergoes efficient in-situ photothermal cross-linking under irradiation conditions. The photothermal PVA-GO layer, synergizing with the ordered UiO-66 nanochannels, provides fast mass transfer pathways. The optimized membrane achieves a high permeation of 148.00 ± 3.87 kg⸱m⁻²⸱h⁻¹ and a salt rejection of 99.95 ± 0.32% for 3.5 wt% NaCl at 75 °C. Remarkably, under 2 kw·m⁻² illumination, the flux increases to 176.74 ± 7.03 kg⸱m⁻²⸱h⁻¹ while maintaining 99.82% salt rejection. More importantly, the membrane showed excellent long-term stability at both 30 °C and 75 °C. In particular, under 72 h alternating dark/light cycling at 75 °C, it exhibited an instantaneous 8.12% flux enhancement upon illumination while maintaining a salt rejection of 99.89%, with complete recovery over repeated cycles. This work offers a sustainable strategy for constructing high-performance, light-responsive membranes for low-energy desalination.