Stabilization of heavy metals in soil using two organo-bentonites. (October 2017)

• Record Type: Journal Article
• Authors: Yu, Kai; Xu, Jian; Jiang, Xiaohong; Liu, Cun; McCall, Wesley; Lu, Jinlong
• Is Part Of: Chemosphere. Volume 184(2017)
• Page Start: 884
• Page End: 891
• Publication Date: 2017-10
• Subjects: Organo-bentonite -- Soil -- Heavy metal -- Stabilization; Pollution -- Periodicals; Pollution -- Physiological effect -- Periodicals; Environmental sciences -- Periodicals; Atmospheric chemistry -- Periodicals; 551.511
• DOI: 10.1016/j.chemosphere.2017.06.040
• Languages: English
• ISSNs: 0045-6535

Abstract

Abstract: Stabilization of Cu, Zn, Cd, Hg, Cr and As in soil using tetramethylammonium (TMA) and dodecyltrimethylammonium (DTMA) modified bentonites (T-Bents and D-Bents) as amendments was investigated. Toxicity characteristic leaching procedure (TCLP) was used to quantify the metal mobility after soil treatment. The structural parameters of modified bentonites, including the BET surface area, basal spacing and zeta potential were obtained as a function of the TMA and DTMA loading at 40, 80, 120, 160 and 200% of the bentonite's cation exchange capacity, respectively. The results indicated that the characteristics of the organo-bentonites fundamentally varied depending on the species and concentration of modifiers loaded on bentonite. T-Bents and D-Bents manifested distinct immobilization effectiveness towards various metals. In association with the organo-bentonite characteristics, the main interactive mechanisms for Cu, Zn and Cd proceeded via cation exchange, Hg proceeded via physical adsorption and partitioning, Cr and As proceeded via specific adsorption and electrostatic attraction, respectively. This study provided operational and mechanistic basis for optimizing the organic clay synthesis and selecting as the appropriate amendment for remediation of heavy metal contaminated soils. Highlights: TMA or DTMA loading at different amount renders distinct structural properties. Stabilization efficiency strongly depends on metal species and clay characteristics. Stabilization of Cu, Zn and Cd mainly proceed via cation exchange. Physical adsorption and partitioning effect are responsible for Hg stabilization. Cr and As can be immobilized by specific adsorption and electrostatic attraction.