A novel amino-functionalized Bio-MOF for trace SO₂ adsorption under dry and humid conditions

Sulfur dioxide (SO₂) adsorption, from the exhaust gas of the industrial processes and vehicles, remains an issue due to the corrosive nature of SO₂. Herein, a novel amino-functionalized bio-derived metal–organic framework, named Bio-ZJU-928(Ni), comprises “paddle-wheel” shaped nickel secondary building unit, acetic acid ligand, and adenine with amino group. It exhibits excellent chemical-thermal stability, specific surface area (634 m² g⁻¹), outstanding trace SO₂ adsorption (2.94 mmol g⁻¹) at 0.002 bar and 273 K, and good cyclical SO₂ adsorption–desorption performance. Bio-ZJU-928(Ni) also has excellent SO₂ selectivity adsorption, identified by its higher ideal adsorption solution theory values for SO₂/N₂ (32,145) and SO₂/CO₂ (259.35) at 10/90 (v/v) and 273 K, respectively. Under relative humidity (50 %), the dynamic SO₂ adsorption of Bio-ZJU-928(Ni) is 32.47 cm³ g⁻¹, which is higher than that of Bio-ZJU-928(Ni) under dry condition (23.08 cm³ g⁻¹) at the mixture gases (N₂/CO₂/O₂/SO₂ = 81.8:15:3:0.2). The enhanced SO₂ adsorption of Bio-ZJU-928(Ni) can be ascribed to the O=S=O···H − O hydrogen bond formed with water, as verified by in situ diffuse reflectance infrared Fourier transform spectroscopy and Grand canonical Monte Carlo simulations.