The Determination of the Stability Constant of Ternary Surface Complexes at Liquid–Solid Interfaces in Natural Water

This article suggests a new method of determining the stability constant of ternary coordination complexes at liquid–solid interfaces in natural water. Its basic principle is based on the rule of left–right shift of an S-type curve, from which the “volcano” curve of exchange ratioE(%) vs concentration of organic matter is obtained. The volcano curve is further used to obtain the stability constant ratios (KSAM/KSM) by using respectively the methods (1) of equality ofE(%) at [H2A] = [H2A]0, and (2) of [H2A]max. From the knownKSM, the stability constantKSAMof a liquid–solid interfacial ternary surface complex can be obtained.