Switchable Carbamate Coagulants to Improve Recycling Ionic Liquid from Biomass Solutions

A reversible amine-carbamate approach has been developed to reduce the use of antisolvents such as water in the coagulation of biopolymers from ionic liquid (IL) solution and thus improve the economy of IL recycle. Cellulose and chitin were recovered from 1-ethyl-3-methylimidazolium acetate ([C₂mim][OAc]) solution by introducing the miscible amines triethanolamine (TEA), ethylenediamine (EDA), or butylamine (BA) and bubbling CO₂ at 40 °C and atmospheric pressure through the solutions to form carbamate salts in situ which resulted in biopolymer coagulation. BA gave the best results because of its low boiling point and low viscosity, which benefited both biopolymer recovery and IL recycle. Cellulose films and fibers could be formed by extrusion of an MCC/[C₂mim]‐[OAc] solution into a coagulating bath comprised of a 1:1 M mixture of [C₂mim][OAc] and butylammonium butylcarbamate (BA-carbamate). The cellulose, IL, amine, and CO₂