Density and viscosity study of nicotinic acid and nicotinamide in dilute aqueous solutions at and around the temperature of the maximum density of water

• Volumetric and transport behaviour of aqueous solutions of important vitamins are reported.
• Various interactions of nicotinic acid and nicotinamide with water have been reported.
• The temperature dependence of interactions between solute and solvent is discussed.
• The study indicates that nicotinamide is more hydrated as compared to nicotinic acid.

In the present study, we report experimental densities (ρ)(ρ) and viscosities (η)(η) of aqueous solutions of nicotinic acid and nicotinamide within the concentration range (0 to 0.1) mol · kg−1 at T = (275.15, 277.15 and 279.15) K. These parameters are then used to obtain thermodynamic and transport functions such as apparent molar volume of solute (Vϕ)(Vϕ), limiting apparent molar volume of solute (Vϕ0), limiting apparent molar expansivity of solute (Eϕ0), coefficient of thermal expansion (α∗)(α∗), Jones–Dole equation viscosity A, B and D coefficients, temperature derivative of B coefficient i.e. (dB/dT  ) and hydration number (nH)(nH), etc. The activation parameters of viscous flow for the binary mixtures have been determined and discussed in terms of Eyring’s transition state theory. These significant parameters are helpful to study the structure promoting or destroying tendency of solute and various interactions present in (nicotinic acid + water) and (nicotinamide + water) binary mixtures.

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