On the interference of urea with CO2/CO32- chemistry of cellulose model solutions in NaOH(aq)

Abstract The CO2/CO32- chemistry of the cellulose/NaOH(aq) solutions has been recently reported to comprise a CO2 incorporation through formation of a transient cellulose carbonate intermediate along with cellulose - CO32- interactions. This work explores on molecular interactions arising when this chemistry is brought together with urea, the most common stabiliser of these solutions. 1H, 13C and steady-state heteronuclear Overhauser effect NMR studies on the cellulose analogues (methyl-β- glucopyranoside (β-MeO-Glcp) and microcrystalline cellulose), combined with pH and ATR-FTIR measurements, reveal concurrent interactions of urea with both CO2 and CO32- leading to increased uptake of CO2 and a buffering effect. Yet, regardless of the presence of urea, the route of conversion from CO2 to CO32-, whether going through reaction with the carbohydrate alkoxides or OH-, is likely to determine the chemical environment of the formed CO32-. These findings shed a new light on a rather overlooked, albeit prominent, interactions of these solutions with the readily absorbed air CO2, essential for further development and implementation, whether towards regenerated and modified cellulose or CO2-capturing concepts.