Lagrangian Mechanics Analysis Of Hydrogen Bond Potentials In Hydrated Solutions

Saline-alkali solution is a ubiquitous and indispensable substance in nature,and plays an important role in human daily life,industrial production,ecological environment,and biomedicine.The hydration of saline-alkali solution is the core link for the solution to play such an important role,and its internal mechanism has always been the focus of research.However,people have not reached a unified understanding of the structure and relaxation mechanism of pure water hydrogen bonding system,and therefore have not reached a common understanding of the intrinsic process of saline-alkali solutes dissolved in water to form solutions.Starting from the coupled hydrogen bond structure of pure water,we abstract saline-alkali hydration as saline-alkali solute dissolved in water and injected into charged particles,thereby inducing the relaxation of hydrogen bonds in water to form hydration,and based on the theory of cooperative relaxation of hydrogen bonds,Lagrangian mechanics and Raman metrology to explore the relaxation behavior of hydrogen bonds under hydration,and quantitatively construct the stimulated evolution map of the short-range local potential field of hydrogen bonds.The main findings are as follows:(1)The salt solute is injected into the water body in the form of ions to form a salt solution,and the formed ionic electric field polarization induces the rearrangement and relaxation of the surrounding water molecules.For monovalent KCl and KBr solutions,with the increase of ion concentration,the O:H non-bond phonon is red-shifted and softened,and the bond is longer and weaker,while the H—O covalent bond phonon is blue-shifted and hardened,and the bond is shorter and stronger.When the concentration is the same,the ionic effect of KBr solution is stronger than that of KCl solution,which conforms to the law of Hofmeister sequence.(2)The hydrogen bond relaxation trend of the divalent salt solution when the ion concentration changes is similar to that of the monovalent salt solution,that is,the O:H non-bond stretching becomes weaker,and the H—O covalent bond compression becomes stronger.At the same concentration,the number of ions in the divalent salt solution is more than that in the monovalent salt solution,so the former has a more obvious effect on the relaxation of hydrogen bonds.However,as the concentration increases,the number of ions in the divalent salt solution further increases,and the interaction between the solute and the solute in the solution cannot be ignored.Instead,the effect of the ionic electric field is weakened,and the hydrogen bond relaxation trend is weakened instead.(3)The super-hydrogen bond O:?:O is formed during the hydration reaction of the alkaline solution.The strong compression acts on the hydrogen bond network.H2O2 is equivalent to containing two OH-,which produces superhydrogen bonds like NaOH and brings about pressure-induced effects in the hydration reaction.The hydrogen bond relaxation trends caused by the two are consistent,that is,with the increase of solution concentration,the O:H phonon is blue-shifted and the bond becomes shorter and stronger,and the H—O phonon is red-shifted and the bond becomes longer and weaker.H2O2 induces the hydration process in the form of molecular clusters,and the diameter of the molecular clusters is much larger than that of a single OH-ion,so the effect on hydration hydrogen bonds is weaker than that of NaOH.(4)Based on Lagrangian mechanics and Raman metrology,we quantitatively constructed the evolution map of the hydrogen bond local potential fields of the above-mentioned monovalent salts,divalent salts and alkaline solutions with solution concentration.Whether it is the polarization of ions or polar molecular groups or the compression of superhydrogen bonds O:?:O,the intrinsic law of hydrogen bond relaxation is the same,that is,the two-segment cooperative relaxation of hydrogen bonds,but the relaxation trend and amplitude varies with incentive conditions.