Abstract
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 (fs-HNT) and carnauba wax-HNT (fw-HNT) in the PVDF membrane enhanced the water contact angle (CA) to 127° and 137°, respectively. The presence of fw-HNT in the PVDF membrane exhibited higher liquid entry pressure (LEP) (2.64 bar) compared to fs-HNT in the membrane matrix (1.44 bar). The PVDF/fw-HNT membrane (Pfw-HNT) obtained the highest flux of 7.24 L/m2h with 99.9% salt removal. A stable permeability in the Pfw-HNT membrane was obtained throughout 16 h of DCMD. The incorporation of fw-HNT in the PVDF membrane had improved the anti-wetting properties and the membrane performance with the anti-fouling effect.
Highlights
Increase in thickness was probably due to the hydrophobic characteristic of functionalized halloysite nanotube (HNT), which delayed the demixing of solvent/non-solvent and resulted in a slow polymer separation phase
The results showed that the addition of the fw -HNT in the poly(vinylidene fluoride) (PVDF) matrix had improved the contact angle (CA) of the membrane to 137◦ with an applicable range of liquid entry pressure (LEP) (2.69 bar) compared to the Pfs -HNT membrane, which was much lower
Hydrophobic membranes have been applied in various applications, the membrane distillation (MD) process
Summary
Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations. Rising demand for freshwater production from saline or brackish natural water resources allowed for a broad utilization of available water resources by Desalination The high usage of seawater desalination for feed water application has overcome the water shortage issue. About 69% of water resources around the world has implemented desalination plants for irrigation due to the cost-effective technology [1]. A challenge is raised for inland desalination when the disposal of brine (desalination by-products) requires a significant addition to the water production cost
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