Structure regulation of PVDF/magnetic attapulgite composite membrane for separating water vapor from air

Dehumidification has been widely used to improve the air quality. However, it is vital to reduce the loss of hygroscopic salt while dehumidifying the air. Hence, a composite dehumidification membrane, i.e., polyvinylidene fluoride (PVDF)/magnetic attapulgite (MATP)/calcium chloride (CaCl2), under the magnetic field was successfully prepared via a solvent volatilization-induced phase separation method. The results showed that MATP enriched the membrane surface, promoting the liquid-liquid phase separation process. It also increased the membrane's porosity and hygroscopicity. The oriented MATP rod crystal structure attached to the spherical crystals yielded capillary action conducive to the adsorption and storage of water vapor and CaCl2 solution on the membrane surface. Hence, the membrane demonstrated 0.986 g·g−1 of water vapor adsorption capacity and good tensile properties. The unique pore structure of ATP and the capillary action of MATP under the effect of magnetic field migration created a channel that reduced about 10 % of the loss of CaCl2 in the membrane. The dehumidification membrane containing MATP showed enhanced antibacterial ability and the antibacterial rate that reached 73.92 %, making the membrane safer and more reliable.