Molecular Dynamics Investigation of the Liquid-Gas Interface Behavior: Simulations of the Sodium Oleate/Sodium Abietate/Water System

Molecular dynamics (MD) simulation was performed to study the sodium oleate/sodium abietate/water system especially on the liquid-gas interface during the process of minerals separation by air flotation. Some representative parameters, such as number density, 2D number density, diffusion coefficient, surface tension, number of hydrogen bonds and solvent accessible surface area were calculated. The simulation results showed that the mixture of sodium oleate and sodium abietate in a suitable ratio contributed to the surface activity of the gas-liquid interface, which could be derived from the distribution state of the molecules. The efficient distribution of surfactants at the interface could reduce the agent loss of froth flotation, reflecting the superiority of mixed-use of surfactants. The self-dispersion of the active groups and the sufficient effective contact area with water revealed the feasibility of this conventional method. The ratio of mixed surfactants with the best flotation activity was NaOL/NaAB = 2/1. These results demonstrated a certain extent of synergy between sodium oleate and sodium abietate at the air/water interface.