Leaching behavior of Cr(III) in stabilized/solidified soil.
The leaching behavior of chromium was studied using batch leaching tests, surface complexation modeling and X-ray absorption near edge structure (XANES) spectroscopy. A contaminated soil sample containing 1330 mg-Cr kg(-1) and 25600 mg-Fe kg(-1) of dry soil was stabilized/solidified (S/S) with 10% cement, 25% cement, 10% lime and a mixture of 20% flyash and 5% lime. The XANES analysis showed that Cr(III) was the only Cr species in untreated soil and S/S-treated samples. The leachate Cr concentration determined using the toxicity characteristic leaching procedure (TCLP) was reduced from 5.18 mg l(-1) for untreated soil to 0.84 mg l(-1) for the sample treated with 25% cement. The Cr leachability in untreated and treated soil samples decreased dramatically as the pH increased from 3 to 5, remained at similar levels in the pH range between 5 and 10.5, and further decreased at pH>10.5. Modeling results indicated that the release of Cr(III) was controlled by adsorption on iron oxides at pH<10.5, and by precipitation of Ca(2)Cr(2)O(5).6H(2)O at pH>10.5.
Jing
Chuanyong
C
Center for Environmental Systems, Stevens Institute of Technology, Hoboken, NJ 07030, USA.
Liu
Suqin
S
Korfiatis
George P
GP
Meng
Xiaoguang
X
D000327:Adsorption; D017610:Calcium Compounds / Q000737:chemistry; D002244:Carbon / Q000737:chemistry; D002484:Cementation; D011232:Chemical Precipitation; D017608:Chromium Compounds / Q000032:analysis*; D060729:Coal Ash; D008956:Models, Chemical; D009515:New Jersey; D010087:Oxides / Q000737:chemistry; D052638:Particulate Matter; D012989:Soil Pollutants / Q000032:analysis*; D012995:Solubility; D018505:Waste Management / Q000379:methods*
D017610:Calcium Compounds; D017608:Chromium Compounds; D060729:Coal Ash; D010087:Oxides; D052638:Particulate Matter; D012989:Soil Pollutants; D002244:Carbon; C016538:lime