Abstract
Biopolymer chitosan was incorporated into a thin multiwalled carbon nanotube membrane (MWNT buckypaper) via filtration and soaking in 0.1% (w/v) of low-molecular-weight (MW) chitosan. The properties of the buckypaper membrane before and after annealing and after soaking were characterized by measurement of their electrical conductivities (19 +/- 2 to 42 +/- 2 S/cm), contact angles (31 +/- 4 degrees to 71 +/- 4 degrees), and mechanical properties (tensile strength, small-ranging between 1.4 +/- 0.1 and 4.2 +/- 0.7 MPa; Young's modulus: 85 +/- 4 to 443 +/- 20 MPa). Moreover, the morphological properties, surface area, and permeability toward water of these buckypaper membranes were characterized and compared with corresponding carbon nanotube membranes prepared with Triton X-100 (Trix) as the surfactant. Scanning electron microscopic (SEM) images and Brunauer, Emmett, and Teller (BET) data of MWNT-annealing buckypaper membranes revealed that the diameters of their surface pores were significantly higher than that of the corresponding buckypaper membranes soaked in chitosan solution. The solution of chitosan incorporated inside the porous structure of the annealed MWNT membrane led to a significantly reduced surface area and pore size distribution of the composite membrane, revealing that this could be a useful method for desalination.