New insights into the adsorption and assembly of mixed collectors with different carbon chain lengths on the low-rank coal flotation by sum-frequency vibration spectroscopy and molecular dynamics simulation

In low-rank coal (LRC) mixed collectors, little attention has been paid to the structure-activity relationship of different carboxylic acids. In this study, the application effect and adsorption mechanism of the mixed collector composed of dodecane (D) and carboxylic acid with different carbon chain lengths (n-valeric acid (VA), ndecanoic acid (DA), myristic acid (MA)) for LRC were explored by using sum-frequency vibration spectroscopy (SFG) and molecular dynamics simulation (MD). SFG measured the groups orientation angle on the LRC surface treated with the mixed collector, revealing that during the interfacial assembly process of mixed collector molecules, D molecules and the main molecular axes of DA molecules with similar carbon chain length tend to be adsorbed parallel to the LRC surface. The MD results showed that adding D -DA could weaken the hydrogen bonding between the LRC surface and interfacial water to the greatest extent, thereby improving every component's diffusion ability.