Department of Agricultural Chemistry and Soil Science, University of Calcutta, 35, Ballygunge Circular Road, Calcutta, 700019.
Present addresses: * College of Agriculture, North-East Hill University, Medziphema, Nagaland, 797 106.
Montmorillonite-HA, illite-HA and kaolinite-HA (20: 1) complexes were studied by IR, TG, ESR and TEM methods. From IR spectroscopy and TG analysis, no significant involvement of the OH groups of the clay minerals in complexation with HA (humic acids) could be detected. Furthermore, there is no detectable interaction of the free radicals of HA with Fe3+/Mn2+ in the clay minerals, as seen by ESR measurements. TEM showed sheet-like forms of free HA in kaolinite-HA complexes and surface deposits in illite-HA complexes. Montmorillonite-HA complexes showed extensive coating by HA as well as a reduction in the size of the clay particles as a consequence of the breaking up of clay platelets by HA.
Clay-humus complexes, infrared spectroscopy, electron spin resonance spectroscopy, thermogravimetry, transmission electron microscopy
