Hollow hydroxyapatite constructs dual channel structured separation membranes for ultra-fast oil-water separation

The discharge of industrial wastewater and frequent oil spills have caused serious harm to the environment, and in order to achieve sustainable development of the environment, membrane separation technology stands out among the many methods for treating oil and water. In this work, hollow hydroxyapatite was grown in situ on Mg Al LDH to construct an oil–water separation membrane with dual channels, and water molecules could not only pass through the porous structure of HAP, but also pass through the gap between HAP and LDH, and the opening of the dual channels greatly improved the oil–water separation speed, and the flux of the petroleum ether emulsion was up to 5208.93 ± 117.62 L/(m2·h·bar) with the separation efficiency up to 99.4 %, and still has 98.8 % rejection rate after 10 cycles, it can efficiently separate many kinds of heavy metal ions and dyes. In order to evaluate the practical performance of the membrane, we found a high rejection rate of 87 % after several cycles of the shale gas fracking wastewater, and this work provides a new idea for the development of oil–water separation membranes with practical applications.