A stabilization/solidification (S/S) process for arsenic (As) contaminated soils was performed using cement kiln dust (CKD) to immobilize As in soils. Slurry samples were prepared using two different types of clays (kaolinite and motmorillonite). Laboratory-prepared slurries and field soils spiked with either 0.1％ (w. t.). As<3+> or As<5+> were subjected to the S/S treatment using varying amounts of CKD. The effectiveness of treatment was evaluated upon 1 day of tumbling and 7 days of aging based on the toxicity characteristic leaching procedure (TCLP). As-CKD and As-Clay-CKD slurries were prepared with either 10％ (w. t. ). As<3+> or As<5+> and then the resulting crystalline phases were analyzed by X-ray powder diffraction (XRPD). Overall, the TCLP results showed that only the As<5+> concentrations in the presence of kaolinite were less than the TCLP regulatory limit of 5mg/L after 1 day of tumbling. The TCLP-As concentrations obtained from montmorillonite samples failed to meet the TCLP criteria within 7 days. In the field soil samples, only the TCLP-As<5+> concentrations obtained from the spiked samples were less than 5mg/L after 1 day of curing. XRPD results showed that Ca-As-O and NaCaAsO<,4>·7. 5H<,2>O were responsible for the immobilization of As<3+> and As<5+>, respectively.
Deok Hyun Moon Mahmoud Wazne In-Ho Yoon Dennis G. Grubb Xiaoguang Meng Christos Christodoulatos
Center for Environmental Systems, Stevens Institute of Technology, Hoboken, NJ 07030, USA Arsenic Geoenvironment Laboratory (NRL), Department of Environmental Science and Engineering, Gwangj Schnabel Engineering North, LLC, 510 East Gay Street, West Chester, PA 19380, USA Center for Environmental Systems, Stevens Institute of Technology, Hoboken, NJ 07030, USA,