Site-Selective Spectroscopy of Adsorbates on Mineral Surfaces using FTIR
Abstract
The montmorillonite clay modification was studied by DRIFT spectroscopy. The modifiers we used were the nonionic modifiers n-heptadecanonitrile (C16 nitrile) and hexadecanamide (C16 amide) which are biologically inert and degradeable. The interaction mechanisms between these modifiers and the montmorillonite clay were investigated. It is found that the polar groups of the modifiers can interact with the specific Si (delta+)-O (delta-)-M(n+) structure of montmorillonite through dipole-ion and dipole-dipole interactions to form a stable complexes. The investigation of a possible hydrolysis of C16 nitrile on the montmorillonite interlayer surface indicated that at a strong acidic condition, the C16 nitrile can be hydrolyzed to form C16 amide which interacts with the montmorillonite clay interface to form a stable ring structure. These results are desirable in the possible application of the modified montmorillonite clay as a waste water treatment agent. The structure of Aldrich humic acid (AHA) and its metal coordination ability are investigated by transmittance Fourier Transform InfraRed (FTIR) spectroscopy, isotopic substitution and reactive substitution were used to assign the IR spectra. A characteristic redox reaction and model compounds were also used for studying a macromolecular AHA. Structure studies have indicated that catechol analogues and phthalic acid analogues are the main functional groups of AHA. It was found that the metal coordination ability of AHA was affected by functional group's characteristics and solution pH. AHA showed higher metal coordination ability at neutral conditions than that at acidic conditions. Catechol analogues coordinate with metal cations to form metal - semiquinone complexes through an oxidation-chelation mechanism.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jan 05, 1998
- Accession Number
- ADA335796
Entities
People
- Keith T. Carron
Organizations
- University of Wyoming