Novel super-hydrophobic carbon nanotube-based nanomaterial for membrane distillation
Membrane distillation (MD) is a low-grade heat-based emerging technology found viable for seawater desalination. Membrane properties such as high hydrophobicity, mechanical strength, and thermal stability are crucial in assessing the compatibility of a membrane for use in this application. In this work, multiwall carbon nanotubes (MWCNTs) were modified with oleylamine (Ol), which is an 18-carbon chain hydrocarbon. The attachment of oleylamine was confirmed via thermal gravimetric analysis (TGA). The modification resulted in an increase in the contact angle (CA) of MWCNTs from 104.0±2.1 to 140.5 ± 6.5°. Non-solvent Induced Phase Separation (NIPS) was then used to fabricate five polyvinylidene fluoride (PVDF) based composite membranes by varying nanomaterial concentration from 0 up to 15 wt% of the polymer. The incorporation of the nanomaterial in the membrane was confirmed via SEM, and fourier-transform infrared radiation. CA, porosity, liquid entry pressure (LEP), and tensile strength were utilized to investigate the membrane properties. A 5% and 15% increase in the CA and LEP, respectively, was observed. An increase in the tensile properties was also achieved, where the membrane consisting of 5.0 wt% nanomaterial exhibited maximum tensile stress of 34.0 MPa, compared to 23.6 MPa in the pristine PVDF. The developed nanomaterials were found to enhance the membrane properties and result in a stable overall flux of the MD system.