Carnauba Wax/Halloysite Nanotube with Improved Anti-Wetting and Permeability of Hydrophobic PVDF Membrane via DCMD

• Main Authors: Wan Aisyah Fadilah Wae AbdulKadir, Abdul Latif Ahmad, Ooi Boon Seng
• Format: Article
• Language: English
• Published: MDPI AG 2021-03-01
• Series: Membranes
• Subjects: polymer-clay; natural wax; FOTS; anti-wetting; membrane distillation
• Online Access: https://www.mdpi.com/2077-0375/11/3/228

The hydrophobic membranes have been widely explored to meet the membrane characteristics for the membrane distillation (MD) process. Inorganic metal oxide nanoparticles have been used to improve the membrane hydrophobicity, but limited studies have used nano clay particles. This study introduces halloysite nanotube (HNT) as an alternative material to synthesis a hydrophobic poly(vinylidene fluoride) (PVDF)-HNT membrane. The PVDF membranes were fabricated using functionalized HNTs (e.g., carnauba wax and 1H,1H,2H,2H-perfluorooctyl-trichlorosilane (FOTS)). The results were determined by Fourier transform infrared-attenuated total reflection, scanning electron microscope, goniometer and porometer to determine the desired hydrophobic membrane for direct contact membrane distillation (DCMD). The addition of FOTS-HNT (f_s-HNT) and carnauba wax-HNT (f_w-HNT) in the PVDF membrane enhanced the water contact angle (CA) to 127° and 137°, respectively. The presence of f_w-HNT in the PVDF membrane exhibited higher liquid entry pressure (LEP) (2.64 bar) compared to f_s-HNT in the membrane matrix (1.44 bar). The PVDF/f_w-HNT membrane (Pf_w-HNT) obtained the highest flux of 7.24 L/m²h with 99.9% salt removal. A stable permeability in the Pf_w-HNT membrane was obtained throughout 16 h of DCMD. The incorporation of f_w-HNT in the PVDF membrane had improved the anti-wetting properties and the membrane performance with the anti-fouling effect.