Nanoparticle transort and membrane associated nanomaterial applications

Overview: 

Fate and Transport of nano TiO2
• Mobility of titanium dioxide nanoparticles (Degussa P25) through highly sorptive iron oxide coated
(IOC) silica beads was examined in both a column format and in batch studies at varying pH and
ionic strength. Uncoated nanoTiO2 was dispersed by sonication at the environmentally relevant
concentrations of 100 ppb, 300 ppb, and 500 ppb.
• Affinity for the IOC decreased with higher pH values, as the surface charge of both materials became
increasingly negative.
• At pH 4 and 5.5, α increased with increasing ionic strength, whereas, at pH 8.3, the α did not change
significantly with increasing ionic strength.

Evaluating colloidal theory for nanoparticle transport with silver NPs and coated silica beads
• Collaborative column studies with Duke and Carnegie Mellon currently underway.
• Extensive preliminary experiments to ensure cohesive data among the three laboratories.
• Will use three types of collector surfaces at 2 pH values: cleaned silica beads (negatively charged),
silanized silica beads (highly adsorbing), and OTS (octadecyltrichlorosilane) coated silica beads
(hydrophobic surface).

Reducing fouling on microfiltration membranes with silver NPs
• Commercially available polyethersulfone (PES) membranes modified with a polyelectrolyte multilayer
(PEM) and silver nanoparticles (nanoAg). Fouling simulated by filtering aqueous solutions
of humic acid, Escherichia coli, and a mixture of both foulants.
• Filtration and cleaning studies showed significantly reduced organic and biological fouling.
• Nano silver addition to the membrane surface resulted in a bactericidal effect.
• Leaching of the silver nanoparticles embedded on the membrane surface averaged 5 ppm.

Biocompatible ultra and nanofiltration membranes
• Surface properties of alumina microfiltration membranes were modified by spin coating the surface with
thin layers of collagen to reject nanoscale materials and create a robust biocompatible NF membrane.
• Molecular weight cut off of the 3 layer modified membranes was 270 kDa and decreased to 80 kDa (6
layers) and 50 kDa (9 layers) as collagen layers increased.
• Permeability, flux and MWCO values for the collagen coated membranes are comparable to
ultrafiltration and loose nanofiltration membranes.

Educating and the Interface: Nanomaterial Environmental Impacts and Policy
• Obtained IGERT on environmental nanotechnology and policy in collaboration with Carnegie Mellon.
• Obtained IGERT on water, climate and health in collaboration with Johns Hopkins.
• Will increase participation by under represented minorities in CEINT activities.