Pulping of Crustacean Waste Using Ionic Liquids: To Extract or Not To Extract

Ionic liquids (ILs), such as hydroxyammonium acetate ([NH3OH][OAc]), can reactively demineralize and remove proteins from shrimp shells in an efficient one-pot pulping process, thus allowing the isolation of native chitin with >80% purity and a high degree of acetylation and crystallinity. Compared to a previously reported IL extraction using 1-ethyl-3 methylimidazolium acetate, [C2mim][OAc], these less expensive ILs can achieve comparable chitin yields and purity, at up to ten times the biomass loading, although potentially result in lower molecular weight (MW) chitin. Because the IL is not recovered or recycled, the cost can additionally be further reduced by the sequential addition of hydroxylamine and acetic acid (or vice versa) to conduct the pulping process in situ. Though each methodology results in a comparable yields and purity of chitin material, the varying production costs and process safety issues are still unknown. This work presents a step toward narrowing the choices for chitin isolation technologies that can lead to an economically and environmentally sustainable process replacing the current hazardous, energy consuming, and environmentally unsafe process.