Acoustic characterization and hydration number analysis of nicotinamide (Vitamin B₃) in aqueous solutions

¹ Department of Physics, GITAM (Deemed to be University) -Hyderabad, Rudraram, Patancheru (M), TS-502329, India
² Department of Physics, CVR College of Engineering, Hyderabad, Vastunagar, Mangalpalli(V), Ibrahimpatnam (M), TS-501510, India
³ Department of Physics, B. V. Raju Institute of Technology Vishnupur, Narsapur, TS– 502313, India

^* Corresponding author: vtalloju@gitam.edu

Published online: 7 January 2026

Abstract

The ultrasonic velocity (u) and density (π) of aqueous nicotinamide (Vitamin B₃) solutions were determined using an Anton Paar DSA 5000 M densimeter–sound velocity analyser at 0.1 MPa. Measurements were carried out over a molal concentration range from 0 to 1.11177 mol.kg^-1 and at temperatures between 298.15 K and 323.15 K. From these experimental data, hydration number (n_H), acoustic properties like apparent molar isentropic compressibility (K_Φ), limiting apparent molar isentropic compressibility (K_Φ⁰) and a semi-empirical interaction factor (S_K) were evaluated. The analysis of these parameters provides insight into solute–solvent interactions, revealing whether nicotinamide acts as a structure-maker or structure-breaker in water. The results also explain the hydration phenomena, acoustic behavior, and structural modifications occurring within these binary mixtures.