The impact of hydrophobic coating on the performance of carbon nanotube bucky-paper membranes in membrane distillation

Self-supporting bucky-papers membranes were processed from chemical vapour deposition grown carbon nanotubes and coated with a thin layer of poly(tetra-fluoro-ethylene) (PTFE) to enhance their hydrophobicity and improve their mechanical stability over time, without drastically changing their average pore size and porosity. Contact angles and bubble point pressure were respectively increased by 23% and 28%. After coating the membranes were tested in a direct contact membrane distillation setup at various feed temperatures with 35 g/L NaCl feed solution and coated samples exhibited improved lifespan and water vapour permeability at salt rejection higher than 99%. The bucky-paper membranes were also compared with commercial PTFE membranes of similar properties.