Deep Potential Molecular Dynamics Study on the Hydrogen Bonding Interactions and Diffusion Behavior of Fluorine in Wet-process Phosphoric Acid

Abstract

The mechanisms underlying the late-stage decline in defluorination efficiency within wet-process phosphoric acid (WPA) remain elusive, as the critical role of fluorine's (F -)hydrogen bonding is often overlooked. This study employs multiscale simulations, combining First-Principles molecular dynamics(FPMD) and Deep Potential molecular dynamics(DPMD), to investigate the evolution of the hydrogen bond network (HBN) and its impact on fluorine migration across varying P 2 O 5 concentrations and temperatures.Our results identify fluorine as the most potent H-bond acceptor in the system. The results reveal a concentration-driven coordination transition: in dilute acid,F preferentially binds to phosphoric acid hydrogen(H p ),whereas in concentrated acid, it forms stronger, shorter H-bonds with hydronium ions(H 3 O + ).DPMD simulations further demonstrate that the evaporation-concentration process densifies the global HBN, increasing its connectivity and rigidity. Collectively, it can be concluded that residual fluorine is immobilized by a dual constraint: strong localized localized H-bond interactions and global HBN topological confinement. This study provides a novel perspective for enhancing industrial defluorination efficiency through H-bond modulation.