Hybrid Membranes Modified with Carbon Nanotubes for Water Purification

New technologies able to effect sustainable, energy efficient water purification are urgently needed to enable future industrial and municipal prosperity. Carbon nanotubes (CNTs) have enormous potential to positively impact water treatment as transformative components in new nano-enabled environmental technologies. One of the most active areas of study involves developing membranes where CNTs are integrated into the water treatment process. This interest is driven in part by the fact that CNTs exhibit extremely high surface area-to-volume ratios, making them attractive as a new class of sorbents for removing chemical and microbial contaminants from water. Recently, we have recently shown that in addition to contaminant removal, microporous CNT mats attached to low pressure membranes (LPMs) also improve fouling resistance, an attribute that will enhance the energy efficiency and sustainability of the hybrid membrane. The Figure below shows that the structure of the CNT mats formed on the surface of polyvinyldifluoride (PVDF) LPMs is extremely sensitive to the CNT diameter; a structural effect that has important ramifications for the mat’s antifouling properties.
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Scanning electron micrograms of (a) an unmodified PVDF membrane, (b) a CNT mat formed on the PVDF membrane by pristine CNTs with diameters > 50 nm and, (c) a CNT mat formed on the PVDF membrane by pristine CNTs with diameters < 8 nm.

Other areas of active research include exploring the effect of CNT surface chemistry on contaminant and virus removal capabilities as well as finding means to attach the CNT mats to the LPMs so that they remain adhered during membrane operation (including backwashing).  This work is being conducted in collaboration with Professors Haiou Huang and Kellogg Schwab at the Johns Hopkins School of Public Health.