Influence of the pH in Reactions of Boric Acid/Borax with Simple Hydroxyl Compounds: Investigation by Raman Spectroscopy and DFT Calculations

The complexation of Boric acid/Borax with hydroxyl compounds is an effective means for the removal and separation of boron in solutions. In this paper, the pH values of the solutions having different molar ratios of boron to hydroxyl compounds including Ethanol, isopropanol, Propanol, 1,2 propanediol, 2,3 butanediol, Glycerol, Xylitol, D-fructose, D-sorbitol, and D-mannitol were determined and analyzed to study the reaction of Boric acid/Borax with different hydroxyl compounds. Solution Raman spectroscopy and DFT calculation were performed to confirm the observations. It was found that the complexation of borate with hydroxyl alcohols follow the order of monohydric alcohols < dihydric and trihydric alcohols < polyols. For polyols, the OH configuration plays very important role in the complexation, and xylitol has the strongest complexation among the polyols at the same molar ratios of boron to polyols.