Relationship between Partition Data and the Adsorption of some Herbicides by Soils

Abstract

THE widespread use of organic pesticides has led to an increasing interest in the adsorption of such solutes from aqueous solution by soil colloids because of the influence of this process on pesticidal performance, mobility in the soil and residue problems. The mechanisms involved are not clearly understood because of the complicated balance between soil–solute, solute–water and water–soil interactions. It seems possible, however, that in systems in which ionic forces are unimportant, adsorption may be related to the hydrophilic–hydrophobic balance of the solute. An inverse relationship has been observed¹ between the hydrophilic–hydrophobic balance of some proteins and their interaction with a paraffin surface as measured by paraffin–water interfacial pressures. Ward and Holly² have recently found partition between cyclo-hexane and water to be related to the adsorption of a number of s-triazine herbicides by nylon and cellulose triacetate, although they considered that with these adsorbents the process involved the formation of a solid solution. The object of the present investigation was to determine whether a relationship exists between hydrophilic–hydrophobic balance and the adsorption of a number of non-ionic solutes by soil.