Experimental and MD Studies of Sorption of n-Butanol and Butyl Acetate on the SiO₂ Surface

The adsorption/desorption of n-butanol and butyl acetate on the SiO₂ surface was studied experimentally by thermokinetic spectrometry and computer molecular dynamic (MD) simulations (temperature, energy, and structural characteristics of adsorption). Radial distribution function (RDF) profiles were constructed and analyzed based on the MD modeling data for the “surface (SiO₂)–carrier gas (Ar)–target molecule (n-butanol/butyl acetate)” ternary system at three temperatures of the system: T = 300, 500, and 700 K. A comparative analysis of the results suggests that the addition of an acetate group enhances the affinity of the butyl acetate molecule for the SiO₂ surface. Consequently, the adsorption of butyl acetate occurs more completely at higher temperatures compared with the adsorption of n-butanol. In addition, changes in the size influence the atomic arrangement in the butyl acetate molecule relative to the SiO₂ surface atoms, leading to the observed “displacement” of the carbon skeleton atoms of the ( \({\text{C}}_{1}^{{(Q = -3)}}\) – \({\text{C}}_{2}^{{(Q = -2)}}\) – \({\text{C}}_{3}^{{(Q = -2)}}\) – \({\text{C}}_{4}^{{(Q = -1)}}\) – \({\text{O}}_{1}^{{(Q = -2)}}\) ) chain for both (n-butanol and butyl acetate) molecules. According to the experimental data on n‑butanol and butyl acetate desorption from the SiO₂ surface in the n-butanol/SiO₂/argon (butyl acetate/SiO₂/argon) ternary system, the activation energy of desorption is 78.83 (87.58) kJ/mol, and the pre-exponential factor is 4.41 × 10⁷ (1.81 × 10¹⁰) s^–1.