An Environmentally Benign Cycle To Regenerate Chitosan and Capture Carbon Dioxide by Ionic Liquids

Abstract

A new cycle platform has been built to provide an efficient method for biomass utilization and greenhouse gas control simultaneously via the interplay of interactions between ionic liquids (ILs), chitosan, and CO₂. All samples, including chitosan/IL solutions, chitin/IL solutions, and pure ILs, were employed to perform experiments on CO₂ capture/release. The results indicated that chitosan with a high degree of deacetylation can capture CO₂ in a nearly 2:1 stoichiometry. In the meantime, different mechanisms of chitosan regeneration from acetate-based ILs and others were explored. For the acetate-based ILs, ¹H and ¹³C NMR spectroscopy implied the formation of new species of [imida⁺–COO^–] after the chemical CO₂ capture, while only the changes of volume expansion and solvatochromic UV–vis parameters can give rise to chitosan regeneration for the ILs with less basic anions. In addition, raw chitosan was used to demonstrate the cycle by selective capture of CO₂ and precipitation from [Bmim]­OAc using compressed CO₂