Effect of Heat Treatment on Sorption of Polar and Nonpolar Compounds to Montmorillonites and Soils
- Dan Lva,
- Yuqiu Wan *a,
- Xin Shiab,
- Huaizhou Xu,
- Wei Chenc and
- Dongqiang Zhua
- a State Key Lab. of Pollution Control and Resource Reuse/School of the Environment, Nanjing Univ., Jiangsu 210093, China
b Chinese Academy of Sciences, Changchun, Jilin 130033, China
c W. Chen, College of Environmental Science and Engineering/Tianjin Key Lab. of Environmental Remediation and Pollution Control, Nankai Univ., Tianjin 300071, China. Assigned to Associate Editor Joseph Pignatello
Batch sorption isotherms of 1,3,5-trichlorobenzene, 1,3,5-trinitrobenzene, and tetracycline to organic-free montmorillonites and soils receiving heat treatment (375°C for 24 h) were compared with those to unheated sorbents. Sorption of the nonpolar 1,3,5-trichlorobenzene to soil was lowered after the removal of humus by heating, consistent with the mechanism of hydrophobic partition into organic matter. For 1,3,5-trinitrobenzene, the enhanced sorption to heated soils was attributed to specific interactions with exchangeable cations facilitated by heating-induced irreversible partial dehydration of the clay interlayer. For tetracycline, an additional mechanism for sorption enhancement could be due to increased exposure of strong complexation sites on clay minerals after removal of the humic coating. These hypotheses were supported by the sorption data to heated and unheated Na+–, K+–, and Cs+–saturated montmorillonites. The combustion method is commonly adopted to measure the content of black carbon in soils and sediments. However, findings from the present study indicate that combustion may greatly modify the structural properties of clay minerals, leading to misinterpreted sorption contributions of different soil components to sorption of polar or ionic compounds.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
Copyright © 2012. . Copyright © by the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America, Inc.