Effective Delivery of Iron Nanoparticles by Amphiphilic Polysiloxane Graft Co-polymeric Vehicles for Groundwater Remediation (Phases I-III)


Researchers: Sita Krajangpan, Achintya N. Bezbaruah, Bret Chisholm

Project sponsors: USGS/NDWRRI (03/2007-02/2008)


Nanoscale zero-valent iron (NZVI) particles have been surface modified and used for contaminant remediation. NZVI tend to agglomerate due to magnetic and van der Waals forces and form larger particles that settle down in aqeous media. NZVI particles are used for contaminant remediation and the remediation process is known to be surface area mediated. Agglomeration increases particle size and decrease specific surface area which leadsto decrease in their reactivity. A novel amphiphilic polysiloxane graft copolymer (APGC) was designed, synthesized and used to coat NZVI to overcome the agglomeration problem. APGC was composed of hydrophobic polysiloxane, hydrophilic polyethylene glycol (PEG), and carboxylic acid. The APGC was successfully adsorbed onto the NZVI surfaces via the carboxylic acid anchoring groups and PEG grafts provided dispersibility in water. The APGC possessing the highest concentration of carboxylic acid anchoring group provided the highest colloidal stability. It was also found that the colloidal stability of the APGC coated NZVI remained effectively unchanged up to 12 months. The sedimentation characteristics of APGC coated NZVI (CNZVI) under different ionic strength conditions (0-10 mM NaCl and CaCl2) did not change significantly. Degradation studies were conducted with trichloroethylene (TCE) and arsenic [As(V)] as the model contaminants. TCE degradation rates with CNZVI were determined to be higher as compared to bare NZVI. Shelf-life studies indicated no change in TCE degradation behavior by CNZVI over a 6-month period. As(V) removal batch studies with CNZVI were conducted in both aerobic and anaerobic conditions. Increase in arsenic removal efficiency was observed with CNZVI as compared to bare NZVI in both aerobic and anaerobic conditions. Ionic strengths showed minimal (4-8%) inhibiting effect on arsenic removal by CNZVI.


Related Publications:

Journal Publications

Journal Publications
Krajangpan S, Kalita H, Chisholm BJ, Bezbaruah AN.  2012.  Iron nanoparticles coated with amphiphilic polysiloxane graft copolymers: Dispersibility and Contaminant Treatability. Environmental science & technology. 46:10130–10136. (2.51 MB)