A direct method for measuring adsorption from solution onto solids

A direct method of measuring solution adsorption onto a solid has been developed. The results are exactly the same as those given by the conventional method of measuring the change in composition of the solution upon contacting the adsorbent. The development is cast in the terms of Gibbsian surface concepts, from which the correct thermodynamic significance of adsorption measurements made by directly analyzing material adsorbed on the solid can be understood. The method was tested for the adsorption of Na-Laurate and n-hexanol from aqueous and n-decane solutions, and typical isotherms are presented. The various realized and potential advantages of the method are discussed. The most important of these are the ability to measure adsorption in complex systems with a negligible change in solution composition, and the possibility of ameliorating in certain situations some of the difficulties in measuring adsorption at high concentrations or on low surface area solids.