Systematic Computational Approaches on Biosorption of Fluoride on Chitin: Crossover from Conventional to Short and Strong Hydrogen Bonds

The present work uses computational quantum chemical methods to predict the fluoride adsorption behavior on the chitin surface. Molecular electrostatic potential analysis dictates the number of active sites available on chitin for the fluoride interaction. The study revealed that fluoride ions interact with chitin via hydrogen bonding, leading to an increased level of fluoride adsorption and enhancing the stability of the chitin–fluoride complex. The atoms in molecules and energy decomposition analysis confirm the H-bonding interaction between fluoride and chitin. Further, noncovalent interaction analysis and infrared vibrational frequency data support the strong H-bonding interaction as the fluoride ions increased on the chitin surface. Interestingly, the study also suggested that fluoride exhibits bridging hydrogen bonds, which could enhance the stability of the chitin–fluoride complex. The interaction of fluoride ions with chitin shows a crossover from conventional to short and strong hydrogen bonds, which are responsible for the biosorption of fluoride in the system. Further, the ab initio molecular dynamics simulation confirms the stability of the chitin–fluoride complex through postfluoride adsorption. The study offers valuable insights into the interaction of fluoride on chitin surfaces and can pave the way for future research directions.