Sorption Characteristics of Organic Compounds on hexadecyltrimethylammonium‐Smectite

TLDR

When HDTMA replaces metal cations in smectite, the clay’s sorptive properties are greatly modified. The authors propose using HDTMA–smectite complexes to improve containment in clay landfill liners and bentonite slurry walls. The HDTMA–smectite acts as a dual sorbent, with the mineral fraction adsorbing and the HDTMA phase partitioning organic compounds, as demonstrated with benzene, TCE, and water vapor. HDTMA–smectite shows much stronger partitioning of benzene and TCE than ordinary soil organic matter, making it an effective sorbent for removing these contaminants from water.

Abstract

Abstract When hexadedyltrimethylammonium (HDTMA) ion is exchanged for metal cations like calcium in smectite, the sorptive properties of the clay are greatly modified. The resultant HDTMA‐smectite complex behaves as a dual sorbent, in the sorption of organic compounds, in which the mineral fraction functions as a solid adsorbent and the organic (HDTMA) phase as a partition medium. Capacities of mineral adsorption and partition uptake by HDTMA in the HDTMA‐smectites are illustrated by sorption of benzene, trichloroethene (TCE), and water as vapors on the dry sample and by sorption of benzene and TCE from water. The exchanged HDTMA in clay is found to be a much more powerful partition medium than ordinary soil organic matter in the uptake of benzene and TCE. Based on this finding, HDTMA‐smectite appears to be an effective sorbent for removing organic contaminants from water. It is suggested that such sorptive organo‐clay complexes could be used to enhance the containment capabilities of clay landfill liners and bentonite slurry walls.