An Integrated Computational Study of Dissociative Adsorption of Hydrogen Fluoride Over Ca(OH)2 Cluster

Hydrogen fluoride (HF) represents a hazardous byproduct released during the thermal degradation of fluorinated polymers in electronic waste (e-waste). Its efficient capture is essential for environmentally responsible processing and recycling of such materials. In this work, we perform an integrated computational study based on Density Functional Theory (DFT) to elucidate the interaction mechanism and thermos-kinetics of HF adsorption over a calcium hydroxide Ca(OH)₂ cluster. The simulation results reveal a two-step dissociative adsorption mechanism, in which HF physisorption entails a very low activation barrier of 2.6 kcal mol⁻¹, followed by cleavage of the H–F bond with an activation barrier of 23.8 kcal mol⁻¹. Hydrogen transfer occurs between two adjacent hydroxyl groups with a barrier of 27.9 kcal mol⁻¹, resulting in the formation of a water molecule. The final step involves desorption of H₂O with an energy of 21.4 kcal mol⁻¹, producing a stable Ca–F configuration analogous to CaF₂. The low activation barriers and exothermic nature of the adsorption reactions suggest that Ca(OH)₂ is a highly suitable material for halogen acid fixation. • Effective capture of HF is vital for safe recycling of fluorinated e-waste. • This study examines HF fixation on Ca(OH) 2 clusters using DFT calculations. • A two-step dissociative adsorption converts HF into stable CaF 2 residues. • Fluorocarbons show both elimination and dissociative pathways. • Mechanistic insights highlight Ca(OH) 2 as a sustainable recycling agent.