MP4 Organic, Metallic, Organometallic Pollutants and Method
Monday, 14 November 2005: 8:00 AM - 6:30 PM in Exhibit Hall

(SAR-1117-658141) Pathways of carbon tetrachloride reduction using nano sized zero valent iron.

Tratnyek, P¹, Sarathy, V¹, ¹ Oregon Health & Science University, Beaverton, OR, USA

ABSTRACT- Zero valent iron has been used extensively in treating groundwater plumes contaminated with carbon tetrachloride (CT), a known carcinogen. Though the rates of CT degradation are rapid, the predominant product formed under typical environmental conditions has been chloroform (CF), which is more toxic and recalcitrant than its precursor. Our work is aimed at studying conditions that promote an alternative mechanism for degradation of CT that produces relatively benign products like carbon monoxide (CO) and formate. Factors such as pH and buffer (organic vs. inorganic) do not have a significant effect on the product distribution. We also studied the effect of iron loading and iron type. To this end, we did batch reactions with both nano- and micron-sized zero valent iron. Nano-sized iron has been thought to exhibit greater reactivity in these reactions. However, in our experiments with nano iron, we found both types of iron (nano and micron sized) to have similar reactivity on a surface area normalized basis. One particular type of nano iron gave a lower yield of chloroform than usually observed. This might provide the basis for treatment of CT contaminated groundwater in the future, such that less toxic products are formed. There might consequently be potential implications in toxicological pathways in the physiological realm, and bioremediation pathways in the biological realm.

Key words: carbon tetrachloride, zero valent iron, remediation, nanotechnology