Electrical double layer on silver iodide. Influence of temperature and application to sol stability

Abstract

Results on the double layer charge and capacitance on AgI previously obtained have been improved and extended to include the temperature dependency between 5 and 85°C. At room temperature, alkali ions adsorb specifically on negative AgI, which gives rise to a marked ion specificity in the double layer capacitance and which is responsible for the lyotropic sequence in the coagulation concentrations. With increasing temperature, charge and capacitance decrease, with a concurrent decrease in specificity. At 65°C and above, the double layer is predominantly diffuse and non-specific. The lyotropic sequence in the coagulation concentrations is then also lost. There is some evidence for a phase transition around 50°C in the adsorbed water layer.