Organo-montmorillonites as carbon paste electrode modifiers

Alkylammonium derivatives of montmorillonite (standards SAz-1 and SWy-2, Source Clay Repository (USA)) were prepared by sorption of hexadecyltrimethylammonium, benzyldimethylhexadecylammonium and hexadecylpyridinium cations. Characterization of the prepared alkylammonium montmorillonites by means of X-ray diffraction and infrared spectroscopy proved a presence of alkylammonium cations in the montmorillonites structure. Intercalation as well as ion exchange process is supposed during the alkylammonium cation sorption into the montmorillonite structure. Cyclic voltammetry of the pair [Fe(CN)6]3−/4− on carbon paste electrodes modified with the alkylammonium derivatives exhibited slightly different electrochemical behaviour of the derivatives in comparison with the original montmorillonites. Sorption properties of all alkylammonium derivatives were studied by means of batch sorption experiments (sorption of Cu, Zn, Pb) as well as by means of voltammetry of Cu(II) on carbon paste electrodes modified with the montmorillonites. The metal sorption was decreased on about 50 % in the case of the alkylammonium montmorillonites. Both techniques showed a significant decrease of Cu(II) sorption in the case of montmorillonites modified with the alkylammonium cations.