Solidification/stabilization of hexavalent chromium contaminated soil

Conference · Wed Dec 31 04:00:00 EST 1997

OSTI ID:567816

Vipulanandan, C; Wang, S ^[1]

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1. Univ. of Houston, TX (United States)

Cement-based solidification/stabilization (S/S) procedure is one of the cost effective methods for treating metal waste in situ. Hence its efficiency in treating hexavalent chromium, Cr(VI), contaminated soils was evaluated in this study. Due to its oxidizing potential and high solubility in water Cr(VI) is highly toxic. Contaminated soils were prepared in the laboratory by spiking soils with hexavalent chromium (K{sub 2}CrO{sub 4}) up to a concentration of 25,000 mg/kg. The control soil was prepared by mixing sand, kaolinite clay and organic matter to represent a clayey soil. Contaminated soils were treated with cement with and without a reducing agent ferrous chloride. Cement-to-soil ratio was varied from 0.2 to 1.0 in the treatment study. Treated soils were cured for 28 days before testing. Contaminated soil with 500 mg/kg of K{sub 2}CrO{sub 4} was effectively treated with cement (cement-to-soil ratio of 0.2) to meet the TCLP limit of 5 mg/L. However, S/S treatment was not successful with the contaminated soil with a contamination level of 25,000 mg/kg K{sub 2}CrO{sub 4}. Increasing the cement-to-soil ratio reduced the leaching of chromium and improved the unconfined compressive strength. Reaction products after treatment were identified using X-ray diffractometry (XRD). Ferrous chloride (FeCl{sub 2}) (4% by weight) was used in S/S treatment to reduce the leaching of chromium by reducing the soluble Cr(VI) to some insoluble forms of chromium. However, adding FeCl{sub 2} had a deleterious effect on cement setting and strength. An empirical model was used to predict the leaching of total chromium and Cr(VI) from the binder matrix.

• OSTI ID: 567816
• Report Number(s): CONF-971032--
• Country of Publication: United States
• Language: English

Related Subjects

54 ENVIRONMENTAL SCIENCES
58 GEOSCIENCES
CEMENTING
CHROMIUM
ECOLOGICAL CONCENTRATION
ENVIRONMENTAL ENGINEERING
ENVIRONMENTAL TRANSPORT
REMEDIAL ACTION
SOILS
SOLIDIFICATION