Application of vibrational spectra in the studies of cation sorption on zeolites

The work describes results of spectroscopic studies (MIR, FIR and Raman) of zeolites on which sorption of various metal cations, namely Pb2+, Cd2+, Cr3+, Zn2+, Cu2+ and Ag+ has been carried out. Sorption has been performed on sodium forms of natural zeolites (clinoptilolites from various sources) using aqueous solutions of the metals studied. Changes in intensities and positions of the pseudolattice bands corresponding to ring vibrations have been observed in the measured spectra. Pseudolattice bands are located in the range of ca. 400–700 cm−1. The degree of changes depends on both, the type of the cation sorbed and the extent of deformation of zeolite ring units. This, in turn, is connected with the way of metal ions binding to aluminosilicate framework of the zeolite, i.e. the proportion of ion exchange and chemisorption in the process.Results of spectroscopic studies have been compared with those obtained by atomic absorption spectrometry (AAS).