Interfacial stepwise ion/coordination particle exchange isotherm and isotherm equation on suspended marine particles

This article deals with a new type of isotherm discovered in sea water systems. The characteristics of this type of isotherm are the non-linear exponential relationship in the low concentration region and the isotherm composed of two or three “S” curves with one or two plateaus in the middle. This isotherm cannot be expressed by the isotherm equation used in marine chemistry at present.⁷] Besides, there has been no report in literature about this type of isotherm in so far as the reaction of minor elements on hydrous oxides is concerned. In order to explain theoretically this type of isotherm, this article suggests the use of the theory of interfacial stepwise ion/coordination particle exchange (for simplicity, ion exchange is used herein-after) of suspended particles to deduce a corresponding isotherm equation. Proceeding from the isotherm of this article, we made theoretical analyses of these two characteristics as well as experiments in verification thereof. Twenty-four systems of experiments on this new type of isotherm and isotherm equation were designed and conducted. Experiment results agree with the theory reported here. Project supported by the Science Fund of the Chinese Academy of Sciences.