Cellulose interactions with CO2 in NaOH(aq): The (un)expected coagulation creates potential in cellulose technology

Journal article, 2022

Upon the search for a suitable processing method for cellulose, the dissolution in NaOH(aq) presents a real green potential, including its ability to sorb environmental CO2(g) affecting dissolution. Here, CO2(g) was delivered in a controlled way to the cellulose/NaOH(aq) system during the in-situ analysis with FTIR, pH and temperature meters, resulting in efficient coagulation of cellulose. Surprisingly, the coagulation occurred with a minimal loss of alkalinity. This was considered an effect of a specific interaction between the dissolved polymer and gas, resulting in the introduction of carbonate species, highly influential in the coagulation process. The process repeated at 25 °C and 5 °C suggested a strong influence of temperature. The conversion routes of the CO2(g) coagulant were also related to the dissolved state of the polymer. The recovered cellulose appeared competitive with EtOH recovery in terms of structure. The presented finding put a perspective on the utilisation of both the coagulation process and final materials in cellulose technology.