Mid-infrared and infrared emission spectroscopy of Cu-exchanged montmorillonite

Abstract

Middle Infrared Spectroscopy (Mid-IR) and Infrared Emission Spectroscopy (IES) were employed to characterise Cu-exchanged montmorillonites, which were derived from two different types of montmorillonite clays, Ca-exchanged montmorillonite (Cheto clay) and Na-exchanged montmorillonite (Miles clay). Copper was exchanged under both acidic and basic conditions at different Cu/clay ratios. All Cu-exchanged montmorillonites experienced a shift in most of non-lattice bands, with hydroxyl bands playing a major role in the characterisation of the clays. Furthermore, a relationship between the ratio of bands at 3630 and 3500 cm(-1) and the Cu concentration of the starting solutions was indicated and used to compare the degree of cation exchange between two preparation methods. Two dehydration stages were observed in the IES experiments. Additional bands were observed in all Cu-exchanged montmorillonites prepared with the 'basic conditions method,' and these bands were assigned to ammonia molecules trapped within the clay structure or absorbed on the surface of the clay.

Copper acetylacetonate anchored onto amine-functionalised clays

“…In the low energy region, the Lap spectrum also shows a broad and intense band centred at 1010 cm −1 assigned to Si-O stretching vibrations [33], one band at 658 cm −1 due to O-H bending of adsorbed water, and an intense peak at about 450 cm −1 assigned to Si-O bending. For K10, the Si-O stretching vibrations of the tetrahedral layer appear over the range of 1200-1000 cm −1 ; a peak at 528 cm −1 due to Si-O-Al (octahedral Al) and one at 463 cm −1 due to Si-O-Si bending vibrations are also observed [4,5,31,34]. There is a shoulder at about 917 cm −1 corresponding to bending modes of structural Al-OH-Al [4,5,31,32].…”

“…4A and 4B, show in the range 3750-3000 cm −1 two components associated with OH stretching vibrations: for Lap, it shows a peak at approximately 3684 cm −1 corresponding to Mg-OH stretching vibration and a shoulder near 3626 cm −1 corresponding to Si-OH stretching vibration [6], whereas for K10 the spectrum shows a band at 3623 cm −1 , with a shoulder at about 3692 cm −1 , due to stretching vibrations of OH groups coordinated to octahedral cations (mainly Al, but also Mg and Fe) [4,5,31]. Both spectra also present two bands associated with the presence of interlayer H 2 O (physisorbed water): a broad band centred at 3457 cm −1 for Lap and 3435 cm −1 for K10 associated with OH stretching vibration and a band at 1643 cm −1 for Lap and 1632 cm −1 for K10, related to OH deformation [4][5][6]31,32]. In the low energy region, the Lap spectrum also shows a broad and intense band centred at 1010 cm −1 assigned to Si-O stretching vibrations [33], one band at 658 cm −1 due to O-H bending of adsorbed water, and an intense peak at about 450 cm −1 assigned to Si-O bending.…”

Influence of heating on the solid acidity of montmorillonite: A combined study by DRIFT and Hammett indicators

“…This result was supported by XRD of NH 3 adsorbed montmorillonite and its heated products (see Supplementary material II). L:NH 3 , NH 4 + , and the hydrogen-bound NH 3 coexisted in the interlayer space of montmorillonite (Benjelloun et al, 2001;Chourabi and Fripiat, 1981;Kloprogge et al, 2006;Park et al, 2002;Petit et al, 1998;Pironon et al, 2003;Trombetta et al, 2000), considering that physically adsorbed NH 3 was removed at 120°C. The corresponding characteristic bands of the hydrogen-bound ammonia (~1630 cm − 1 ) overlapped with the bands of NH 4 + and L:NH 3 , respectively (Basila and Kantner, 1967;Dontsova et al, 2005;Fripiat et al, 1965;Mortland and Raman, 1968;Trombetta et al, 2000), and were hard to be distinguished.…”

Preparation and characterization of antibacterial silver/vermiculites and silver/montmorillonites

“…Similarly, involves contribution of Mg 3 OH + Mg 2 AlOH + Si-O bending vibrations (Farmer, 1974). The bands at 456 cm À1 and at 443 cm À1 involve bending vibrations Si-O-Si and Si-O-M, where M is Mg, Al and/or Fe (Madejová and Komadel, 2001;Kloprogge et al, 2006). The spectra of M1 and V1 show new bands with position near 1400 and 1430 cm À1 , respectively, which usually correspond to the N-H bending.…”