Highly Efficient Hydrophobic Titania Ceramic Membranes for Water Desalination
2014
Kujawa, Joanna | Cerneaux, Sophie | Koter, Stanisław | Kujawski, Wojciech
Hydrophobic titania ceramic membranes (300 kD) were prepared by grafting of C₆F₁₃C₂H₄Si(OC₂H₅)₃ and C₁₂F₂₅C₂H₄Si(OC₂H₅)₃ molecules and thus applied in membrane distillation (MD) process of NaCl solutions. Grafting efficiency and hydrophobicity were evaluated by contact angle measurement, atomic force microscopy, scanning electron microscopy, nitrogen adsorption/desorption, and liquid entry pressure measurement of water. Desalination of NaCl solutions was performed using the modified hydrophobic membranes in air gap MD (AGMD) and direct contact MD (DCMD) processes in various operating conditions. High values of NaCl retention coefficient (>99%) were reached. The permeate fluxes were in the range 231–3692 g·h–¹·m–², depending on applied experimental conditions. AGMD mode appeared to be more efficient showing higher fluxes and selectivity in desalination. Overall mass transfer coefficients (K) for membranes tested in AGMD were constant over the investigated temperature range. However, K values in DCMD increased at elevated temperature. The hydrophobic layer was also stable after 4 years of exposure to open air.
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