The solubility and diffusion coefficient of oxygen in potassium hydroxide solutions

The solubility of oxygen in aqueous KOH solutions has been measured by a Van Slyke apparatus and by an adsorption technique developed by Hildebrand. In the range of concentration of KOH between 0 and 12 N, at 25°C, the two methods yielded identical results; at 760 torr oxygen partial pressure, log S = log 1·26 × 10−3 − 0.1746 C, where 0·1746 is the solubility coefficient, S the concentration of oxygen, g-mol/l, and C the concentration of KOH, g-mol/l. Between 0° and 60°C both the solubility and the solubility coefficient decrease with increasing temperature. Diffusion coefficients of oxygen in aqueous KOH were evaluated from the limiting current of oxygen on a rotating disk electrode, and also by a stagnant tube technique similar to that used by von Stackelberg. The diffusivity drops sharply with increasing KOH concentration, and increases with temperature. At 25°C and for KOH concentrations between 2 and 4 N, the product of the diffusivity and the viscosity is constant: Dμ = 1·3 × 10−7 g.cm/s2, where D is the diffusivity, cm2/s, and μ is the viscosity in poise. At 60°C and for 1 < N KOH < 8, the value of this product is Dμ = 1·9 × 10−7 g.cm/s2.