Abstract
Surface deposition of silica nanoparticles (SiNPs) is widely used for constructing omniphobic membranes for membrane distillation (MD) with an aim of creating hierarchical and reentrant textures. Herein, we report a comprehensive analysis of the effects of physical properties of SiNPs on membrane performance from the viewpoint of their dimensions and morphologies. An emerging fabrication technology, i.e., the electrospray method, was also investigated and systematically compared to the conventional solution deposition. SiNPs with spherical dimensions of 30 nm aggregated significantly in solution deposition process, forming a surface layer with uncontrollable defects and becoming vulnerable to inorganic fouling. While membranes utilizing SiNPs with a diameter of 200 nm showed severe pore blocking, which resulted in much lower operational fluxes. However, the fluxes could be improved by 20–50% using hollow mesoporous SiNPs, where the intrinsic cavities provided extra channels for vapor transport. More importantly, using a high-voltage electric field in the electrospray procedure resulted in a uniform distribution of SiNPs, thereby endowing an ideal membrane surface layer for a robust MD operation. The proposed study provides new insights into the effects of the physical properties of SiNPs, and shows the advantage of electrospray technology in fabricating defect-free MD membranes for sustainable applications.
Published Version
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