A G4MP2 and G4 theoretical study on reactions occurring during the ozonation of bromide containing waters

摘要

The thermodynamic properties of chemical reactions proposed to occur during the ozonation of bromide containing waters were examined via high-level G4MP2 and G4 composite theoretical methods with the SMD, PCM, and CPCM solvation models. Enthalpies and free energies of reaction for the sequential oxidation of bromide to bromate and related reactions were determined under standard state conditions. For a select subset of reactions where entropic changes were significant, the effects of varying temperature in the range of 0-100 ℃ were also considered. Based on the current work, previously proposed BrOO~-, BrOOO~-, and BrO_4~- intermediates thought to exist during the bromide ozonation process are called into question. Similarly, bromide oxidation reactions involving Br_2O_4, BrOH~-, and HO_2Br appear to be speculative. Analogous to the chloramines, the aqueous phase production of bromamines from hypobromous acid and ammonia is predicted to be highly energetically favorable.