Hydrophobic metal-organic framework@graphene oxide membrane with enhanced water transport for desalination

Abstract

As a new generation of high-performance alternative, graphene-based membranes have shown great prospect in water purification. Among them, numerous efforts are concentrated on designing hydrophilic membranes while less attention is paid to hydrophobic membranes, which limit the potential application of graphene-based membranes, such as desalination via membrane distillation (MD) process. Anisotropic heat transfer and easy hydrophobic modification of graphene oxide (GO) make it suitable for MD membrane fabrication. Herein, we developed a novel porous and hydrophobic MOF-801@GO-PDMS membrane with enhanced water vapor transport for water desalination via direct contact membrane distillation (DCMD). MOF-801 nanoparticles were in-situ grown within GO interlayer followed with vacuum filtration to fabricate MOF-801@GO membrane which was subsequently modified with polydimethylsiloxane (PDMS) to fabricate the MOF-801@GO-PDMS membrane. The water-stable porous MOF-801 nanoparticle was introduced to increase the porosity of GO laminate and provide extra water vapor transport channels. PDMS was employed to ensure the membrane hydrophobic stability by utilizing its intrinsic hydrophobicity and segment entanglement. The optimum MOF-801@GO membrane exhibited water flux of 29.24 kg m−2 h−1 and NaCl rejection of over 99.99%, as well as robust stability during continuous DCMD desalination test. This work not only gives a promising candidate for water desalination, but also provides a method to design hydrophobic and porous graphene-based nanostructures for other potential applications.