Browsing by Author "Rashid, MHO"

Now showing 1 - 2 of 2
  • No Thumbnail Available
    Item
    Nanofiltration applications of tough MWNT buckypaper membranes containing biopolymers
    (Elsevier, 2017-05-01) Rashid, MHO; Triani, G; Scales, N; in het Panhuis, M; Nghiem, D; Ralph, SF
    The ability of biopolymers (bovine serum albumin, lysozyme, chitosan, gellan gum and DNA) to facilitate formation of aqueous dispersions of MWNTs was investigated using a combination of absorption spectrophotometry and optical microscopy. Subsequently, self-supporting carbon nanotube membranes, known as buckypapers (BPs), were prepared by vacuum filtration of the dispersions. Microanalytical data obtained from the BPs confirmed the retention of biopolymers within their structures. Tensile test measurements performed on the BPs showed that incorporation of the biopolymers resulted in significant improvements in mechanical properties, compared to analogous BPs containing MWNTs and the low molecular mass dispersant Triton X-100. For example, MWNT/CHT BPs (CHT=chitosan) exhibited values for tensile strength, ductility, Young's modulus and toughness of 28±2MPa, 5.3±2.7%, 0.9±0.3GPa and 1.7±0.3J g−1, respectively. Each of these values are significantly greater than those obtained for MWNT/Trix BPs, prepared using a low molecular weight dispersant (6±3MPa, 1.3±0.2%, 0.6±0.3GPa and 0.10±0.06J g−1, respectively). This significant improvement in mechanical properties is attributed to the ability of the long biopolymer molecules to act as flexible bridges between the short CNTs. All BPs possessed hydrophilic surfaces, with contact angles ranging from 29±2° to 57±5°. Nitrogen gas porosimetry showed that the BPs have highly porous internal structures, while scanning electron microscopy (SEM) showed their surface morphologies have numerous pore openings. The permeability of the BPs towards water, inorganic salts, and dissolved trace organic contaminants (TrOCs), such as pharmaceuticals, personal care products, and pesticides, was investigated through filtration experiments. Of the twelve TrOCs investigated in this study, nine were rejected by more than 95% by BPs composed of MWNTs and chitosan. The latter BPs also demonstrated good rejection of both NaCl (30–55%) and MgSO4 (40–70%). © 2017 Elsevier B.V.
  • No Thumbnail Available
    Item
    Synthesis, properties, water and solute permeability of MWNT buckypapers
    (Elsevier, 2014-04-15) Rashid, MHO; Sweetman, LJ; Alcock, LJ; Wise, A; Nghiem, LD; Triani, G; in het Panhuis, M; Ralph, ST
    High power tip sonication was used to prepare dispersions containing multi-walled carbon nanotubes (MWNTs), or multi-walled carbon nanotubes functionalised with carboxylic acid groups (MWNT-COOH) or amine groups (MWNT-NH2). The dispersion of carbon nanotubes was facilitated by the presence of a surfactant (Triton X-100) or various macrocyclic ligands (derivatised porphyrin, phthalocyanine or calixarene) in the solution. Vacuum filtration of the dispersions afforded self-supporting membranes known as buckypapers. Microanalysis provided evidence for retention of the surfactant or macrocyclic ligands in the buckypapers, which were also characterised by measurement of their electrical conductivities (24±16 to 58±11 S/cm), contact angles (28±1° to 55±10°) and mechanical properties (tensile strengths varied between 1.6±0.7 and 13±2 MPa). The surface and internal morphologies of the buckypapers were similar to each other, which correlates with the lack of variation observed in their permeability's towards water. The ability of selected buckypapers to remove trace organic contaminants (TrOCs) was also examined. A buckypaper prepared using Triton X-100 as the dispersant showed more than 80% removal efficiency for 11 out of the 12 TrOCs investigated in this study. On the other hand, a buckypaper prepared from MWNTs and phthalocyaninetetrasulfonic acid exhibited lower removal efficiencies for these TrOCs, possibly due to their smaller specific surface area. © 2014, Elsevier B.V.