Adsorption on Nonionic Surfactants by Soil Materials

The adsorption of nonionic surfactants by various soil materials from solution was measured. Most studies were on Aqua Gro and Soil Penetrant—surfactants marketed for use on soils. Aqua Gro was generally adsorbed to a greater extent than Soil Penetrant. Essentially all of Aqua Gro was adsorbed from solution until a given amount of surfactant was adsorbed after which there was only a slight increase in adsorption as the concentration in solution increased. Soil Penetrant, on the other hand, was adsorbed to a lesser extent until the concentration in solution was increased to about 500 ppm. At this concentration, there was a very great increase in adsorption to a maximum value after which very little additional adsorption occurred as the solution concentration increased. Equilibrium between the soil and solution was either complete or near completion after one hour. Essentially no Aqua Gro was desorbed as the treated soil was placed in water. Some of the adsorbed Soil Penetrant went into solution as treated soil was placed in water. Since the reaction between soil and surfactant differs for various surfactants, the surfactant which would have optimum properties for a desired effect can be chosen. Additional