S. Akyuz et al., FT-IR spectroscopic investigation of adsorption of 3-aminopyridine on sepiolite and montmorillonite from Anatolia, J MOL STRUC, 565, 2001, pp. 487-491
The adsorption of 3-aminopyridine by natural sepiolite and montmorillonite
from Eskisehir (Anatolia) was investigated in the temperature range from 20
to 125 degreesC by infrared spectrometry using a variable temperature unit
. The spectroscopic results indicate that the 3-aminopyridine molecules ads
orbed on sepiolite are coordinated to Lewis acidic sites and/or surface hyd
roxyls by H-bonding interaction through pyridine ring nitrogen lone pairs.
Surface Bronsted acid strength of sepiolite is weak and 3-aminopyridinium i
s not detected under the conditions applied in this study. It must be noted
that the adsorption of aminopyridine affected the hydroxyl group vibration
s of sepiolite. The intercalation of 3-aminopyridine within montmorillonite
has been shown by X-ray diffraction to increase the interlayer spacing. IR
spectroscopy indicates that sorbed 3-aminopyridine molecules by montmorill
onite are mostly coordinated to exchangeable cations directly or indirectly
through water bridges. The formation of 3-aminopyridinium cation is also d
etected at elevated temperatures. (C) 2001 Elsevier Science B.V. All rights
reserved.