Remediation of hexavalent chromium contaminated soil by stabilized nanoscale zero-valent iron prepared from steel pickling waste liquor

The removal of Cr(VI) from contaminated soil using sodium carboxymethyl cellulose (CMC)-stabilized nanoscale zero-valent iron prepared from steel pickling waste liquor was systematically investigated. Laboratory batch experiments indicated that 0.09 g L⁻¹ of Fe⁰ nanoparticles at a soil to solution ratio of 1 g: 10 mL completely reduced the aqueous-bound Cr(VI), which contributed about 46% of the pre-sorbed Cr(VI) in the soil (Cr(VI) = 102 mg kg⁻¹). Furthermore, the addition of Fe⁰ nanoparticles only removed a portion of the soil-bound Cr(VI). When the soil was treated with 0.3 g L⁻¹ of Fe⁰ nanoparticles for 72 h, 80% of the loaded Cr(VI) was reduced to Cr(III), which resulted in a residual Cr(VI) concentration of 20 mg kg⁻¹. Based on the studies of elemental distributions and XPS analysis, it is proposed that reduction and immobilization may be equally important removal mechanisms for Cr(VI) by CMC-nZVI. Following the treatment by CMC-nZVI, the TCLP leachability of the Cr(VI) and Crtotal was significantly reduced by 100% and 82%, respectively. This study sheds new light on the remediation of Cr(VI)-contaminated soil by CMC-nZVI. Copyright © 2014 Elsevier B.V. All rights reserved.