Ionic molar volumes in methanol mixtures with acetonitrile, N,N-dimethylformamide and propylene carbonate at T = 298.15 K

• Densities of electrolyte solutions in methanol mixtures were measured at T = 298.15 K.
• Apparent molar volumes of sodium cation and iodide anion were determined.
• TPTB as a calculation method was used.
• Preferential solvation of ions by organic solvents was examined.

The densities of dilute solutions of three electrolytes (NaI, NaBPh4 and Ph4PI) in methanol mixtures with propylene carbonate (PC), N,N-dimethylformamide (DMF) and acetonitrile (AN) have been measured by Anton Paar 5000 densimeter at T = 298.15 K. Apparent molar volumes, VΦ have been determined at an electrolyte concentration of 0.06 mol · kg−1 over the entire mixed solvent composition range. Single ionic apparent molar volumes of transfer, ΔtVΦ (ion) were calculated using the tetraphenylphosphonium tetraphenylborate (TPTB) assumption. The results are discussed in terms of ionic preferential solvation.