Systematic Computational\nApproaches on Biosorption\nof Fluoride on Chitin: Crossover from Conventional to Short and Strong\nHydrogen Bonds

The present work uses computational quantum chemical\nmethods to\npredict the fluoride adsorption behavior on the chitin surface. Molecular\nelectrostatic potential analysis dictates the number of active sites\navailable on chitin for the fluoride interaction. The study revealed\nthat fluoride ions interact with chitin via hydrogen bonding, leading\nto an increased level of fluoride adsorption and enhancing the stability\nof the chitin–fluoride complex. The atoms in molecules and\nenergy decomposition analysis confirm the H-bonding interaction between\nfluoride and chitin. Further, noncovalent interaction analysis and\ninfrared vibrational frequency data support the strong H-bonding interaction\nas the fluoride ions increased on the chitin surface. Interestingly,\nthe study also suggested that fluoride exhibits bridging hydrogen\nbonds, which could enhance the stability of the chitin–fluoride\ncomplex. The interaction of fluoride ions with chitin shows a crossover\nfrom conventional to short and strong hydrogen bonds, which are responsible\nfor the biosorption of fluoride in the system. Further, the <i>ab initio</i> molecular dynamics simulation confirms the stability\nof the chitin–fluoride complex through postfluoride adsorption.\nThe study offers valuable insights into the interaction of fluoride\non chitin surfaces and can pave the way for future research directions.