Tracer caffeine diffusion in aqueous solutions at 298 K. The effect of caffeine self-association

Abstract

Tracer diffusion coefficients for caffeine in aqueous solutions are reported for the complete caffeine solubility range (0–0.1 mol dm–3) at 298 K. The results show a strong concentration dependence and are interpreted in terms of caffeine self-association. On the basis of a simple equilibrium model, estimates for the diffusion coefficients of the caffeine dimer and trimer are obtained.