Experimental evidence supporting distinct adsorption configurations of N,N-bis(2‑hydroxy-3-chloropropyl) dodecylamine and dodecylamine on apatite surfaces: Quartz crystal microbalance and atomic force microscopy studies

Abstract

In apatite flotation, a novel amine collector N,N-bis(2‑hydroxy-3-chloropropyl) dodecylamine demonstrates a considerably lower collecting ability than dodecylamine. Nonetheless, studies under identical dosage conditions reveal that the adsorption amounts of N,N-bis(2‑hydroxy-3-chloropropyl) dodecylamine on apatite surface surpass those of dodecylamine. The collecting efficiency of a collector is traditionally linked to its adsorption amount on the surface of a mineral, suggesting that a collector's efficacy increases with its adsorption amount. However, this study indicates that factors beyond adsorption amount significantly impact a collector's efficiency. Through first-principles calculations, it has been discovered that N,N-bis(2‑hydroxy-3-chloropropyl) dodecylamine and dodecylamine possess markedly varied adsorption configurations on apatite surfaces, implying that the variation grant them divergent collecting capabilities in apatite flotation. Supporting these findings, quartz crystal microbalance and atomic force microscopy analyses show the adsorption layer of dodecylamine is nearly triple thickness of N,N-bis(2‑hydroxy-3-chloropropyl) dodecylamine, with a notably different adsorption morphology. These results offer experimental validation of their differing adsorption configurations. This study not only strengthens the theoretical framework for developing selective control technologies of mineral flotation behaviors but also offers more perspectives for designing innovative collector molecules.