Mild pre-heating of organic cation-exchanged clays enhances their interactions with nitrobenzene in aqueous environment

作者：Borisover Mikhail^*; Bukhanovsky Nadezhda; Lapides Isaak; Yariv Shmuel

来源：Adsorption, 2010, 16(4-5): 223-232.

DOI：10.1007/s10450-010-9224-3

• Organoclays
• Thermal treatment
• Sorption enhancement
• Montmorillonite
• Water-sorbate competition
• Clay hydration

Aqueous sorption kinetics and equilibrium isotherms of nitrobenzene were studied on two series of sorbents that were prepared by (i) replacing inorganic exchangeable cations in Wyoming bentonite with tetraethylammonium (TEA) and benzyltrimethylammonium (BTMA) and (ii) heating synthesized complexes in air at different temperatures (between 150 and 420A degrees C). The aim of this work was to examine recently observed enhancement of aqueous sorption of a probe organic sorbate on organoclays after mild thermal pre-treatment of sorbents. Thermal pre-treatment of TEA- and BTMA-clays at 150A degrees C results in the maximal enhancement of nitrobenzene-sorbent interactions as compared with treatment of original bentonite and its exchange complexes formed with long-chain quaternary ammonium (n-hexadecyltrimethylammonium, HDTMA). Based on C, N content data and FTIR spectra of TEA- and BTMA-clay complexes, no indications of decomposition of organic matter were found in organoclays heated at 250A degrees C (and below this temperature). Suppressed hydration of pre-heated sorbents resulting in a lessening of water-organic sorbate competition for sorption sites is considered to be responsible for thermally induced enhancement of nitrobenzene-sorbent interactions. In the HDTMA-based organoclays, the long-chain aliphatic groups of the quaternary ammonium can additionally interact with clay surface thus competing with organic sorbate-sorbent surface interactions and, in this way, mitigating the enhancement of nitrobenzene sorption on thermally treated sorbents.

• 出版日期2010-10