Molecular dynamics simulation of the interaction between ionic liquid [OPy][BF4] and SO2

Ionic liquids possess novel properties and can efficiently absorb harmful gases, potentially serving as a new type of absorbent. In this study, the binary system of ionic liquid N-octylpyridinium tetrafluoroborate [OPy][BF₄] and sulfur dioxide (SO₂) has been selected as the research object, and the structure and properties of the system have been studied by molecular dynamics simulation. The interaction between SO₂ and ionic liquids is explored by using the radial distribution functions (RDFs), coordination numbers (CNs) and spatial distribution functions (SDFs). The results of microstructures show that due to the strong interaction with anions, SO₂ is mostly orderly distributed around the anions of ionic liquids. However, the coordination ability of the polar region of the ionic liquid and SO₂ is nearly equivalent to that of the non-polar region. At the same time, it is found that the addition of SO₂ enhanced the order degree of the polar and the non-polar regions of ionic liquids, especially on non-polar regions. Through the discussion of the interaction between [OPy][BF₄] and SO₂, it can be concluded that the mechanism of SO₂ absorption by [OPy][BF₄] is the combined effect of anions and cations. This study aims to provide new insights for the potential applications of ionic liquids in industrial fields such as petroleum and flue gas desulfurization.