The Characterization and Capture of Mercury from Broken Fluorescent Light Bulbs

In 2004, approximately 514 million mercury-containing lamps entered the solid waste stream, leaking as much as 2-4 metric tons of mercury into the environment either as a vapor or dissolved in groundwater. This study seeks to understand the evaporation behavior of mercury from broken, unused compact fluorescent bulbs (CFL's), and to engineer a solution to permanently capture the released mercury. The release was characterized by placing a CFL (made by n:vison, containing 5 mg of mercury) in a flow system and analyzing the nitrogen coming out of the bulb-containing chamber. It was found that nitrogen flow rate over the broken bulb had little effect on the evaporation rate, implying that evaporation is limited by some internal resistance. A commercial sulfur-impregnated activated carbon (HgR) shows promise as an effective sorbent, with a mercury capacity as high as 13 weight percent in a saturated environment. Breaking a single CFL in the presence of 1 gram of HgR and sealing the system in a Teflon bag for 24 hours reduces the initial mercury release rate by a factor of 10, and reduces the evaporation rate 10 hours after atmospheric exposure by 73%.