DETERMINATION OF PROTON AFFINITY DISTRIBUTIONS FOR CHEMICAL-SYSTEMS IN AQUEOUS ENVIRONMENTS USING A STABLE NUMERICAL-SOLUTION OF THE ADSORPTION INTEGRAL-EQUATION

A stable numerical method for the solution of the adsorption integral equation (SAIEUS) is applied to the analysis of potentiometric titrati on data. A continuous distribution of acidic constants is assumed. The method combines the regularization principle with the B-spline repres entation of the distribution function. The resolution and reliability of the method are tested on the data obtained for citric acid which is treated as an organic standard. The pK distribution obtained for citr ic acid consists of three well-separated narrow peaks at pK values cor responding to its pK constants. Integrated areas of the peaks are in e xcellent agreement with the stoichiometric composition of citric acid. The applicability of the method for characterization of the acidic pr operties of different materials is further demonstrated using example potentiometric titration data obtained for an ion exchanger, clay mine rals, and oxidized activated carbon. The approach presented enables on e to assess both qualitatively and quantitatively the number and stren gth of acidic sites. (C) 1995 Academic Press, Inc.