Cold-sintered self-assembly of layer-ordered hydroxyapatite nanowire arrays for efficient oil/water separation

Modified membranes and block materials with abundant porous structures have been extensively studied for oil/water separation due to their unique wettability and high specific surface area, crucial factors for high separation efficiency. This study used oleic acid to induce the hierarchical self-assembly of hydrophobic hydroxyapatite nanowires during the cold sintering process, producing a dense, layer-wise stretchable block structure. This cold sintering process sample exhibits interlayer expansion when immersed in water, spatially transitioning from a dense block to a loose, two-dimensional hydrophobic film. The small-volume, dense block contains a hydrophobic layer structure, enriching the specific surface area and integrating the advantages of hydrophobic membranes and block materials with a high specific surface area, offering a novel approach to creating dense and efficient oil/water separation materials. It grants an economical and environmentally friendly solution for large-scale oil/water separation in practical applications.