Colloidal Behavior and BaSO4 Nanoparticles Formation during Phase Separation in a Binary Tetrahydrofuran-Water Solvent System

Abstract

Barium sulfate nanoparticles have garnered considerable attention owing to their physicochemical characteristics, such as high density, high corrosion resistance, and chemical inertness. These characteristics render them suitable for promotion as a novel material for many medicinal and industrial uses. Nonetheless, difficulties remain in regulating their shape and attaining monodispersity, especially with particle size distribution. This study examines the role of tetrahydrofuran (THF) in enhancing the uniformity of barium sulfate nanoparticles and inhibiting their agglomeration. The nanoparticles were produced using direct precipitation in an aqueous THF solvent solution and examined by transmission electron microscopy (TEM) to evaluate shape and size distribution. The inclusion of THF led to a more uniform size distribution and decreased aggregation relative to a pure water solvent system. The ideal molar ratio of water to THF for achieving monodispersed nanoparticles was established as 0.656:1. The findings indicate that THF improves particle stability by altering interfacial interactions and creating a transitional layer that facilitates regulated nucleation in lyophobic colloids. This layer influences the movement of particles in circular flows analogous to Marangoni cells at surfaces that exhibit lower polarity and increased hydrophobicity. The dynamics of buoyancy in this transition layer and the instability between the adsorption layer and the film bulk augment the inhibition of particle growth. In this solvent system, the diffusion rate shows a proportional correlation with the inverse of viscosity in accordance with the Stokes-Einstein equation. This study demonstrates a simple and efficient method for altering the morphology of BaSO4 nanoparticles, which may be advantageous for targeted drug delivery systems and the production of polymer fillers.