Abstract
Ion adsorption is one of the most important characteristics of soil. There have been many studies on ion adsorption in soils which have been carried out to elucidate the adsorption mechanisms. However, few studies have been carried out to elucidate them by determining changes in electric conductivity. Determining changes in electric conductivity is a more precise method than pH determination in the adsorption mechanisms when the ionic compositions of the solution systems are known. On the other hand, the existence of charged particles disturbs the correct measurement of electric conduction in an aqueous solution. Thus accurate conductivity data for solutions containing suspended solid particles are difficult to obtain using a conventional conductivity cell and the probe of a conductivity meter. This study deals with the development of new conductivity cells for determining electric conductivity of electrolyte solutions containing charged particles.Three types of prototype cells were developed in this study. Each of them was devised to avoid the effect of charged particles. Practical use of the above conductivity cells was also examined by determination of phosphate adsorption on clay minerals at 298.15 K. Clay minerals are one of the inorganic components in soils. Their characteristics are responsible for the chemical properties of soils. Stable conductivity data can be obtained rapidly and precisely by the three prototype cells. This study reached the following conclusions. ( i ) The new procedures for determining micro changes in electric conductivity of electrolyte solutions containing suspended particles were indicated, (ii) Simultaneous determination of changes in electric conductivity and pH will become a good indicator to elucidate the mechanisms of adsorption phenomena.
