Interactions of ammonium smectite with low-molecular-weight carboxylic acids

Abstract

AB ST R ACT : The percolation of water through waste landfill sites produces leachates with large amounts of pollutants. Clay barriers are often used to limit soil and underground water pollution. A better understanding of the interaction between ammonium smectite and carboxylic acids would contribute significantly to our understanding of such systems. The SWy-2 (Wyoming smectite) was exchanged with NH 4 + and then batched with carboxylic acids (acetic, formic, chloroacetic and oxalic) in concentrations between 0.01 M and 1 M. The solid phases obtained were analysed chemically and characterized by infrared absorption spectroscopy (IR) and powder X-ray diffraction (XRD). Ionic chromatography was used for the quantitative measurement of ammonium ions in the solution after the interaction. For the four acids, the interaction was characterized by a cationic exchange of NH 4 + to H 3 O + . A partial exchange to Al 3+ due to a partial dissolution of the sample in strong acidic medium was observed with chloroacetic and oxalic acids for which adsorption of molecules on the clay sample occurs, mainly through H-bonding with the cation. Moreover, the intercalation of oxalic acid in the interlayer space was highlighted.*

Highly Exfoliated Natural Rubber/Clay Composites by “Propping‐Open Procedure”: The Influence of Fatty‐Acid Chain Length on Exfoliation

“…FTIR spectrum of on stearic acid is given here as representative in the present discussion for clarity. It can also be observed from figure that a new peak is appeared at 1 730 cm −1 attributed to the strong interaction between CO group and interlayer cations via water bridge shown in the Figure 5b 47. This indicates that fatty acid molecules intercalate the interlayer space of OMMT and again supports the results obtained from WAXD patterns.…”

“…It can be observed from Figure 5a that a broad peak appears at 3 430 cm −1 is attributed to the hydroxyl stretching vibrations (free and interlayer water molecules) in OMMT 47. Alternatively, the major band 1 705 cm −1 shown in the figure can be assigned to the stretching vibrations of CO groups present in the C18 fatty acid.…”

Adsorption Mechanisms of Psychoactive Drugs onto Montmorillonite

“…That is why acidification of the solution avoids the participation of edge-sites in the CEC of the whole clay minerals. Moreover, acidification of the solution also destabilizes the clay mineral [24], and increases the concentration of H + in the solution. However, H + in excess could be preferentially adsorbed in comparison to other cations such as PADs [23].…”

Analytical indicators to characterize Particulate Organic Matter (POM) and its evolution in French Vertical Flow Constructed Wetlands (VFCWs)

“…The broad band at 1634 cm -1 may be assigned to asymmetric stretching of C=O (νC=O) in carboxylates and aromatic structures (Ellerbrock & Kaiser, 2005;Li et al, 2011;Romero et al, 2007). Water OH bending vibration, often observed in inorganic compounds at 1630 cm -1 , may also contribute (Gautier et al, 2009). The band at 1574 cm -1 may be attributed to C=O stretching vibrations (νC=O) in ketones and quinones (Kim & Yu, 2005).…”