Experimental investigation of the solid - Liquid phase equilibria in the water - Ammonium methanesulfonate and in the water - Sodium methanesulfonate systems

The thermal stability of ammonium and sodium methanesulfonates was investigated under inert atmosphere by thermogravimetry. Temperatures and enthalpies of phase transitions were determined for these salts by means of differential scanning calorimetry (DSC). It was shown that sodium salt melts congruently. Solid - liquid phase equilibria in the binary water - salt systems were studied. It was found that hydrate is formed in the water - sodium methanesulfonate system. Melting parameters and composition of this hydrate (NaSO3CH3·8H2O) were evaluated with the help of DSC. The data on the density of the methanesulfonates aqueous solutions in a wide range of concentrations at 25.00 °C were obtained.