Volatilizing toxic metals from soil
- Univ. of Houston, TX (United States). Dept. of Civil and Environmental Engineering
This study revealed that lead, cadmium, mercury, zinc, arsenic, and selenium can be volatilized from both spiked and actual contaminated soils by heating in inert or reducing atmospheres. Generally oxygen proved to be detrimental to the remediation process. An apparatus capable of rapidly heating soil samples to as high as 1,100 C was designed and built to volatilize toxic inorganic contaminants from 500-mg soil samples while purging with hydrogen, nitrogen, or nitrogen/oxygen mixtures. An average of 93% lead removal was observed for PbSO[sub 4]-, Pb(NO[sub 3])[sub 2]-, PbCO[sub 3]-, Pb[sup 0]-, and PbO-spiked soil samples aged for up to two years with initial lead concentrations of 2,000 mg/kg soil when heated for 20 minutes at 900 C in a flowing stream of hydrogen or nitrogen. About 50% lead removal was achieved at 750 C for all the compounds at these conditions. Similar results were obtained for lead-contaminated soil from a battery waste site. Under the same conditions, a sample containing 8,220 mg Pb/kg soil yielded 93% lead removal in hydrogen or nitrogen, but only 73% lead removal in air. Other toxic metals and metalloids also proved amenable to removal from soil by volatilization. The temperatures required for approximately 90% removal during 10 minutes heating in nitrogen were as follows: mercury 370 C, cadmium 550 C, zinc 850 C, arsenic 500 C, and selenium 700 C. Further experiments with oxygen added to the purge gas showed that as little as 1% oxygen significantly lowered the removal of metals, particularly at the lower volatilization temperatures. These experimental results are encouraging; they suggest that the controlled-temperature-metal-volatilization technique is potentially applicable for the permanent lean up of metal contaminated soil.
- OSTI ID:
- 5607982
- Journal Information:
- Waste Management; (United States), Vol. 13:5-7; ISSN 0956-053X
- Country of Publication:
- United States
- Language:
- English
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