520 15 0 u00b1 1 1 1 20 0 0 u00b1 0 0 0 0______________________________________ these sorption evaluations indicate that all of the resulting sorption isotherms corresponded to the linear equation where x m is the amount of material sorbed per unit mass clay mg kg c is the equilibrium concentration mg l and k is the sorption coefficient typical and representative isotherms are illustrated in fig2 and 5 which show the results for toluene in fig2 the slope k of the isotherm plot indicates the degree of sorption or preference for the sorbed species by the silane modified clay the linearity of the fig2 plot indicates a partitioning mechanism as opposed to an adsorptive process if partitioning is in fact the controlling sorption mechanism then one expects k values to increase as water solubility decreases to evaluate this possibility a series of six compounds of varying water solubility were investigated the resulting data when shown as plot of k values vs water solubility as shown in fig3 resulted in a straight line with a coefficient of correlation r value of 0 987 thereby confirming the existence of a partition mechanism fig4 shows the effect of varying i e increasing.