Abstract:

Molecular modeling techniques were employed to investigate the selective adsorption mechanism of NaCl with collector dodecylmorpholine(DMP) in halite-carnallite reverse flotation system. Adsorption models of DMP on halite and carnallite surfaces were constructed and optimized using Material Studio 4.0 program and COMPASS force field method, molecular dynamics simulation and minimization method were used to search the most favorable adsorption models.We conclude that DMP adsorbs on the interfacial water structure of halite (100) surface by hydrogen bonding between the oxygen and nitrogen atoms in the functional group of DMP and hydrogen atoms in the water structure. The interaction energy between them was found to be -119.49 kJ·mol-1. The structure of water on carnallite surface is not stable, which allows DMP direct contact with carnallite surface at a smaller adsorption energy of -37.97 kJ·mol -1. Because of the difference in adsorption energies of DMP with the two minerals, we assumed that DMP preferentially adsorbs on halite surface in the flotation process.

Key words: Molecular modeling, Selective adsorption, Dodecylmorpholine(DMP), Collector, Carnallite, Reverse flotation