フッ素及びホウ素の土壌吸着に関する基礎的研究

Abstract

The adsorption equilibrium tests on fluorine and boron were carried out using several soils (Kuroboku, Yellow brown forest, Kanuma and Peat). Then various analysis and considerations were done on the basis of the experimental results.Adsorbed amount of fluorine per unit mass of soil was ranged as Kuroboku ≒ Yellow brown forest > Kanuma > Peat. Adsorbed amount of boron per unit mass of soil was ranged as Yellow brown forest > Kuroboku ≒ Kanuma > Peat. It was clear that there was less correlation between the BET specific surface area of the soils and the adsorbed amount of fluorine or boron. The clear correlation between the content of individual element (such as Ca, Mg, Al, Fe and Si) in soils and the absorbed amount fluorine or boron could not be recognized. The quantitative correlation between total carbon content in the soils and the absorbed amount of fluorine or boron could not be also recognized.The applications of an ion exchange model and a surface complexation model to data obtained in this work were unsuccessful because of lack of measurement item. However, the application of Langmuir's adsorption equation to our data except some data was successful basically and the application of Frendlich's adsorption equation was successful significantly. It was clarified the adsorption isotherms of fluorine and boron on the soils are represented using Freundlich's adsorption equation and are unaffected by the mass ratio of soil to liquid. The adsorption coefficients and indexes of fluorine and boron were obtained by using Freundlich's adsorption equation. The utilization of the adsorption parameters makes it possible to estimate the adsorbed amounts of fluorine and boron on the soils or the dissolved concentrations of them into liquid phase.