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(66-02) Adsorption Studies of Paraquat on Indonesian Tropical Soils . Narsito, N*,1, Noegrohati, Sri1, 1 Gadjah Mada University, Yogyakarta, Indonesia ABSTRACT- In the present work, adsorption properties of paraquat (1,1-dimetil-4,4-bipyridinium dichloride) on several type of Indonesian tropical soils have been investigated; including the adsorption rate and the adsorption capacity, the energy involved during the adsorption. As a reference, similar adsorption properties of paraquat on kaolinitic and monmorilonitic clays were also studied. Results show that paraquat adsorption on Indonesian soils is chemisorption, involving energy of adsorption in a range of 23 - 32 kJ/mole. It was observed that except for peat soils, paraquat adsorption on most soils investigated is extremely fast. For soils containing aluminosilicate clays, the adsorption was completed within less than ten minutes; while for peat soils the time required for the complete adsorption was more than two hours. In general, The paraquat strong adsorption capacity of monmorilonite containing soils (25.39 g/kg) was found to be much higher than that of kaolin containing soils (5.67 g/kg); while the strong adsorption capacity of peat soils for paraquat was negligible. Facts that no paraquat adsorption was observed when an elevated temperature sulfuric acid treated clays (kaolinitic and monmorilonitic) were used as the adsorbent, suggest the involvement of a unique chemisorption in the paraquat adsorption. The possibility for the involvement of such transfer adsorption was confirmed spectroscopically Key words: Paraquat, , adsorption, , charge transfer, , aluminosilicate and peat soils |
