Boundary layers between silver iodide and aqueous solutions at low temperatures

Potentiometric titration studies have been made on AgI suspensions over the temperature range 0–20°C, in the presence of LiNO3, KNO3 and RbNO3. Points-of-zero-charge (p.z.c.), double-layer capacities and surface entropy data, derived from the titration results, indicate an increase in water “structure”, as the temperature tends to 0°C, around the p.z.c. region, and particularly on the positive side. For strongly negatively charged surfaces the charge ordering effect on the dipoles tends to break down this structuring. The results of flocculation studies on AgI sols have been combined with the titration data to yield information about changes in double layer parameters with temperature. The results fit the suggestions made regarding changes in water structuring at the interface.