Understanding the characteristics of SO2 capture: Effect of solar-assisted adsorbent, isotherms, kinetics, thermodynamics, and mechanism

The study contributed to developing sustainable clean energy technologies by providing a novel approach for SO₂ capture, which is essential for reducing emissions and mitigating climate change. Due to its high stability and corrosion resistance, reduced graphene oxide (RGO) is preferred for SO₂ capture. In this study, GO was reduced sustainably using sunlight (SARGO) and was employed for SO₂ adsorption. By using various characterization techniques, it was confirmed that the synthesized SARGO adsorbent has a mesoporous structure with potential functional groups, great thermal stability, high surface area (713.4 m²/g), pore size (4.89 nm), and pore volume (0.79 cm³/g). The maximum adsorption capacity and efficiency were 23.72 mg/g and 93.8 %. Sips isotherm and Pseudo-second order kinetic models are more appropriate for relating the SO₂ adsorption to the SARGO adsorbent. Along with thermodynamic studies, the adsorption mechanism and photoreduction mechanism were detailed. The SO₂ adsorption process belongs to exothermic, spontaneous, and physical adsorption. Further, the obtained wide functional groups of O–H, –COOH, and –O– are favorable for SO₂ adsorption onto the adsorbent via hydrogen bonding, acid-base interactions, dipole-dipole interactions, and covalent bonds. SARGO has excellent reusability and stability for industrial applications. The approximate cost was roughly calculated to be $1.25/mg of SO₂ adsorbed onto SARGO adsorbent. The study findings successfully demonstrated the potential for environmental engineering, particularly in air pollution control, sustainable energy, and clean technologies, emphasizing the potential of solar-assisted adsorbents for reducing emissions and optimizing industrial processes. The study provided a thorough understanding of the adsorbent characteristics, including isotherms, kinetics, thermodynamics, and mechanisms, offering valuable insights for industrial applications.