College of Engineering
Materials Engineering Department
BS in Materials Engineering
Trevor Harding, Shanju Zhang
In theory single walled carbon nanotubes (SWCNT) will aid in ion rejection due hydrophobicity and smoothness of the SWCNT. An efficient means of water desalination utilizing SWCNT in a membrane seems plausible. A lyotropic liquid crystal (LLC) solution was made with a synthesized polymerizable surfactant methacryloxy ethyl hexadecyl dimethyl ammonium bromide (C16MA) to help with vertical alignment of SWCNT. Due to SWCNT lack of solubility and tendency to agglomerate in water, a dispersion performed using an inert surfactant centrimonium bromide (CTAB) to make sure that the SWCNT were homogeneously dispersed in the solution without altering the hexagonal packing factor of the LLC, while keeping the viscosity of the solution low. To make sure that the right viscosity was achieved, viscometer testing indicating the solution of 52 wt-% had the optimal viscosity. Moreover, polarized optical microscopy indicated that the 52 wt-% LLC was the critical concentration for the LLC to enter the hexagonal liquid crystal phase. The ultimate goal was then to lock the SWCNT into the hexagonal phase of the LLC by UV-curing the solution unto a polyether sulfone membrane to produce a nano-enhanced composite membrane. Desalination efficiency testing was then performed to determine the ion rejection rate of the membranes, however results were indicative that further improvements are necessary for the solution to properly adhere to the membrane.