Abstract
The paper describes desalination by membrane distillation (MD) using ion-track membranes. Poly(ethylene terephthalate) (PET) ion-track membranes were hydrophobized by the immobilization of hydrophobic vinyl-silica nanoparticles (Si NPs). Si NPs were synthesized by the sol-gel method, and the addition of the surfactant led to the formation of NPs with average size of 40 nm. The thermal initiator fixed to the surface of membranes allowed attachment of triethoxyvinyl silane Si NPs at the membrane surface. To further increase hydrophobicity, ethoxy groups were fluorinated. The morphology and chemical structure of prepared membranes were characterized by SEM, FTIR, XPS spectroscopy, and a gas permeability test. Hydrophobic properties were evaluated by contact angle (CA) and liquid entry pressure (LEP) measurements. Membranes with CA 125–143° were tested in direct contact membrane distillation (DCMD) of 30 g/L saline solution. Membranes showed water fluxes from 2.2 to 15.4 kg/(m2·h) with salt rejection values of 93–99%.
Highlights
The search for effective and affordable water treatment methods is an urgent task due to a decrease in drinking water reserves, and an increase in population and industrialization [1]
membrane distillation (MD) can be realized in five types of configurations: air-gap MD, vacuum MD, sweeping gas MD, permeate gap MD, and direct contact MD (DCMD)
Triethoxyvinylsilane (TEVS), 2,20 -azobis (2-methylpropion-amidine) hydrochloride (ABAP), N-(3-dimethylaminopropyl) -N0 -ethylcarbodiimide (EDC), pentafluorophenol (PFP), 1H, 1H, 2H, 2H-perfluorodecyl triethoxysilane (PFDTS), and isopropanol were supplied by Sigma Aldrich (Hong Kong, China)
Summary
The search for effective and affordable water treatment methods is an urgent task due to a decrease in drinking water reserves, and an increase in population and industrialization [1]. Nations reported that around 700 million people currently live in water-scarce countries. By the year 2025, that 1.8 billion people will live in regions with water scarcity [2]. The most effective methods of water treatment is membrane technologies including osmosis, filtration and membrane distillation (MD) [3]. MD was considered as one of the most promising methods due to the following advantages, such as mild operating conditions, high rates of rejection, low working pressure, less sensitivity to fouling, and low feed temperature requirements [4,5,6,7,8]. MD can be realized in five types of configurations: air-gap MD, vacuum MD, sweeping gas MD, permeate gap MD, and direct contact MD (DCMD)
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