Effect of ionic strength and pH on the adsorption of selected herbicides on Amberlite

The effect of ionic strength on the adsorption of alachlor, trifluralin, and prometryn on Amberlite XAD-4 polymeric resin is studied. Static adsorption experiments are carried out at pH 3-6.5 and ionic strength 0.01-2M at 20 degrees C. By increasing the ionic strength, the adsorption of herbicides can be significantly increased. The electrolyte addition affects both the effectiveness and efficiency of adsorption, leading eventually to a saturation of the resin surface. An explanation of the alteration of adsorption mechanisms, caused by ionic strength, is given, based mainly on the reduction in repulsive forces at the resin-herbicide interface and between adsorbing herbicide molecules, since both resin and herbicides have a polar ring as part of their structure.