Dielectric relaxation in water-tert-butanol mixtures. The water rich region

Measurements of dielectric relaxation in water-tert-butanol mixtures have been performed by means of a frequency domain coaxial technique in the range 0.03–3 GHz, at 5 °C and for an alcohol mole fraction X ranging from 0 to 0.1. Experimental data give evidence for two relaxation processes whose relative amplitude and relaxation time depend on alcohol concentration. A two state model involving hydration and bulk water mutually exchanging at a finite rate is used to interpret dielectric data in the water rich region (X<0.02). An anomalous behavior, evidenced at X*≊0.045, is interpreted as the occurrence of a self-aggregation process involving part of the alcohol molecules in the solution.