INTERACTION OF FLUTRIAFOL WITH THE SURFACE OF SILICA AND LAYER SILICATES

The mechanism of adsorption of flutriafol (GAS #76674-21-0), a large p olyfunctional molecule used in fungicide formulation, from aqueous sol ution on the surface of kaolinite, montmorillonite and silica gel has been studied by combining the use of classical adsorption and kinetic experiments with modern computational methods of chemistry, such as AM 1, MNDO-PM3, molecular mechanics and molecular dynamics. Measurements are reported for the adsorption isotherms at 20 degrees C and the diff usion kinetics of flutriafol in consolidated adsorbents. The contribut ions of different interactions to the total bonding energy have been c ompared. Hydration effects and hydrogen bonding dominate the adsorptio n from aqueous solutions; the characteristics of the most important hy drogen bonds and heats of hydration are reported. Possible influences on the adsorption isotherm of acid-base reactions involving the adsorb ate are discussed. The results suggest that flutriafol probably does n ot penetrate the interlayer spacing of K+-montmorillonite in the condi tions studied, but interacts only with the edge sites with an affinity similar to that measured for K+-kaolinite. (C) 1997 Elsevier Science B.V.