A Simple Diffusion Cell for the Determination of Absolute Diffusion Constants using Radioactive Tracers

Using microscope slides for the diffusion grating, a glass diffusion cell was constructed which permitted the determination of absolute diffusion constants of γ-ray emitting elements in aqueous solutions.The cell was tested at 25 °C with 110Ag as tracer and gave a bulk-diffusion coefficient of 1.64 × 10 −5 cm2/s and a self-diffusion coefficient of 1.48 × 10−5 cm2/s using 0.01 M AgNO3.The hydrogen ion concentration had no detectable effect on the diffusion coefficient of AgNO3 in the pH range −0.48 to 7.5. The presence of Na or Fe(III) ions, or sucrose molecules at moderate concentrations (> 0.1 M) resulted in a marked decrease in the diffusion coefficient.