Carbon Nanotube (CNT) Bucky-Papers (BPs), mats of entangled nanotubes, are promising nano-structures that can be processed from any kind of CNTs at low-cost and on large scales. The versatility of these novel super-porous nano-structures has been demonstrated in a variety of applications, including being efficient mechanical reinforcements for composite materials, excellent supports for nano-particle growth as well as promising gas sensors or ultra-filtration membranes. Here we demonstrate that BPs composite membranes, processed from a number of different and novel approaches (sandwiched, polymer infiltration, surface coating or functional groups grafting…) can be efficiently used as novel sorbents for gas separation and as membranes for water desalination by direct contact membrane distillation. The thorough characterization of the CNT surface functional groups, porosity and pore size was performed in order to control the fabrication of superior performance membranes. The potential of these novel structures will be discussed in light of commercial benchmark materials and structures in line with the current needs in membrane separation.