Adsorption and hydrophobic action of different surfactants on montmorillonite Na-001 surface: a molecular simulation study

Montmorillonite (Mt) is a typical clay mineral in tailings, and its strong hydrophilicity is easy to lead to the instability of tailings dam structure and the difficulty of tailings wastewater treatment. The influence of different types of surfactants on the Mt Na-001 surface hydrophobicity was analysed from the perspective of adsorption energy, electron transfer and concentration distribution. DFT simulation results showed that the adsorption effect of surfactant was cationic > anionic > non-ionic, and the best surfactant were methyl primary amine, methyl sulfonic acid and methyl formate. The MD simulation results of the adsorption of dodecyl primary amine (DDA) and sodium dodecyl sulfonate (SDS) with different coverage on the surface of Mt Na-001 showed that the adsorption effect of DDA and SDS was significantly improved with the increase of coverage, and DDA was significantly better than SDS, and the optimal coverage of DDA was 1 ML. Finally, the reason why DDA is superior to SDS was explained from the concentration distribution of water and Na+ on Mt surface. This simulation calculation study can provide micro-level insights for solving practical engineering problems.