Carbon nanotube enhanced membrane filtration for trace level dewatering of hydrocarbons

A highly hydrophobic membrane prepared by immobilizing carbon nanotubes (CNTs) over PTFE microfiltration membrane is presented for the dewatering of organic-water mixtures containing trace amounts of water. The effects of different CNT concentrations on membrane morphology, wettability, hydrophobicity, porosity, and permeability were characterized. After immobilization of CNT into membranes, the contact angle increased by 9% and 16% compared to unmodified 0.1 μm and 0.22 μm pore sizes membranes respectively. The carbon nanotube immobilized membrane (CNIM) showed remarkable separation efficiency for octane and heptane water systems. The enhanced hydrophobicity of the CNIM helped nano/micro water droplets to coalesce on the CNT present on the membrane surface which led to their rejection. In general, the water rejection increased, and the solvent flux decreased with CNT incorporations. For the octane water system, CNIMs were fabricated with 0.1 and 0.22 μm pore sizes, at the optimized CNT loading of 3 and 6 wt%, the water rejection was 99.87% and 97.60% respectively while the fluxes were 44.947 kg/m².hr and 54.66 kg/m².hr for octane water system. Water rejection for CNIM with 0.1 μm pore size was 99.87% and 99.98% respectively for octane-water and heptane-water systems, which were 20.3% and 20.5% higher compared to one without the CNT coatings.