Self-diffusion of water in a natural hypersaline solution (Dead Sea brine)

The self-diffusion of H₂¹⁸O has been studied empirically in Dead Sea brine (TDS ≈ 340 g/l), a natural, very saline solution composed of mainly Mg and Na chlorides. Experiments were conducted in dialysis cells with ¹⁸O-depleted water at an ambient temperature of 22 ± 1°C. The self-diffusion coefficient in DS water is 1.8 × 10^-5 cm²/sec, about 25% lower than the known self-diffusion coefficient in distilled water. Knowledge of the self-diffusion coefficient in hypersaline solutions is of importance for the determination of mass transfer in brines, at sediment-water interfaces in lakes and in interstitial solutions of saturated and unsaturated porous media in aquifers.