Molecular Dynamics Study of Polyacrylamide and Polysaccharide-Derived Flocculants Adsorption on Mg(OH)2 Surfaces at pH 11.

Brucite (Mg(OH)₂) is a typical precipitate in the mining industry that adversely affects processes such as flotation and thickening. Gaining insights into the physicochemical properties of this mineral is critical for developing strategies to mitigate these challenges and improve operational efficiency. Additionally, incorporating natural-origin polymers aligns with the shift toward more sustainable mining practices. In this study, molecular dynamics simulations were employed to investigate the interaction of brucite with polysaccharides such as cellulose, guar gum, and alginate and to compare these with conventional polymers, including polyacrylamide, hydrolyzed polyacrylamide, and polyacrylic acid, under conditions of pH 11 in low-salinity water. The methodology enhanced adsorption sampling by incorporating additional temporary interactions between the polymer and the brucite surface. The results reveal that neutral polymers exhibit stronger and more stable interactions with brucite compared to charged polymers, which is consistent with the neutral nature of brucite under the studied conditions. Van der Waals forces predominantly govern the adsorption of polysaccharides, while Coulombic forces primarily drive interactions involving polyacrylamides. These findings provide valuable insights into the molecular mechanisms of polymer-brucite interactions, facilitating the development of more effective and sustainable mining additives.