Recycling EDTA solutions used to remediate metal-polluted soils.
The objective of this research was to investigate the recycling of ethylenediamine-tetraacetic acid (EDTA) used for the removal of trace metals from contaminated soils. We successfully used Na2S combined with Ca(OH)2 to precipitate the trace metals allowing us to recycle the EDTA. The results of batch and column leaching experiments show that both Ca-EDTA and Na-EDTA are powerful chelating agents with a similar soil remediation potential. The major advantage of Ca-EDTA is the preservation of soil organic matter. We found that Na2S was capable of separating the metals Cd, Cu and Pb from EDTA; however, the precipitation of Zn required the addition of Ca(OH)2. After reusing the reclaimed EDTA seven times, over a 14-day period, EDTA reagent losses ranged from 19.5% to 23.5%. Successive washing cycles enhanced the removal of trace metals from contaminated soils. The metal sulfide precipitates contain high concentrations of metals and could potentially be recycled.
Zeng
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Department of Natural Resource Sciences, McGill University-Macdonald Campus, 21 111 Lakeshore Road, Ste. Anne de Bellevue, Quebec, Canada H9X 3V9.
Sauvé
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Allen
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Hendershot
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D002104:Cadmium / Q000737:chemistry; D002126:Calcium Hydroxide / Q000494:pharmacology; D002614:Chelating Agents / Q000494:pharmacology*; D011232:Chemical Precipitation; D003247:Conservation of Natural Resources; D003300:Copper / Q000737:chemistry; D004492:Edetic Acid / Q000494:pharmacology*; D005240:Feasibility Studies; D007854:Lead / Q000737:chemistry; D019216:Metals, Heavy / Q000737:chemistry*; D012987:Soil; D012989:Soil Pollutants / Q000032:analysis*; D013440:Sulfides / Q000494:pharmacology; D014131:Trace Elements / Q000737:chemistry*; D015032:Zinc / Q000737:chemistry
D002614:Chelating Agents; D019216:Metals, Heavy; D012987:Soil; D012989:Soil Pollutants; D013440:Sulfides; D014131:Trace Elements; D002104:Cadmium; D007854:Lead; D003300:Copper; D004492:Edetic Acid; D015032:Zinc; D002126:Calcium Hydroxide; C033479:sodium sulfide