Humidity swing adsorption of H₂S by fibrous polymeric ionic liquids (PILs)

A novel H₂S adsorbent, fibrous polymeric ionic liquids (PILs), was proposed in this study, for they combine the advantages of ionic liquids and characteristics of macromolecular architecture. After modified with basic anion, the sorbent showed excellent performance for low concentration of H₂S adsorption under room temperature. The fixed bed breakthrough experiment showed that the adsorption capacity is up to 1.75 mmol/g and the adsorption kinetics is comparable to that of mental oxide at 300 °C. Despite the strong affinity for H₂S, the saturated sorbent could be regenerated under wet conditions, which inspires an economical water-promoting regeneration method. Further investigations through density functional theory (DFT) calculations revealed that the interface water would alter the reaction pathways of H₂S adsorption and lower the activation energy of desorption reaction, which makes H₂S desorption faster. After eight adsorption-desorption cycles, the sorbent did not show any detectable loss of H₂S adsorption capacity. Therefore, the results of this study indicate that the fibrous PILs are promising regenerable sorbent for low concentration H₂S removal at room temperature.