| Clays and humic acids are abundant natural substances. They can interact with organic and inorganic contaminants in aqueous media in many ways. Better understanding of the mechanisms and equilibria involved in these interactions can provide useful information on how to modify and improve these processes so that they can be used to effectively reduce and eliminate various contaminants in groundwater systems.; In this study, I modified montmorillonite clay with biodegradable nonionic modifiers such as heptadecanonitrile and hexadecanamide to form organo-clays. The effect of exchangeable metal cations on the formation of nitrile and amide-clay complexes and the hydrolysis of nitrile-clay complexes were investigated using DRIFT technology. The structures of organo-clays and the behaviors and mechanisms of sorption of benzene to organo-clays in aqueous systems were evaluated.; We examined the structure of Aldrich Humic Acid (AHA) using chemical derivative techniques in association with FTIR spectroscopy. We found that AHA consists mainly of two functional structures: carboxylic acid type and catechol type. By using catechol as a model compound and employing FTIR, ESR, elemental analysis and other instrumental methods, the interaction mechanisms of AHAs and reducible metal ions, such as Fe3+ and Cu2+, and the structure of AHA-metal ion complexes were studied in depth. We found that during metal ion coordination, the catechol structure of AHA could be oxidized to form semiquinone. We propose that the oxidation of catechol could be performed by O2 through catalysis of catechol-metal ion complexes. Furthermore, the sorption equilibrium reaction of AHA with reducible metal ions was modeled and AHA-metal ion coordination equilibrium constants determined based on a Scatchard model. The effect of environmental pH on the sorption equilibrium is also discussed. |
