Torrefied paper as a packaging material and subsequently as a bioethanol substrate: Synergy of torrefaction and alkaline treatment for increased utility

The sequential combination of torrefaction and alkaline treatment is one possible design strategy for a circular economy in which torrefied cellulosic paper with enhanced wet strength is repeatedly used as a packaging material, then hydrolyzed downstream for bioethanol production after alkaline treatment. The wet-tensile strength of cellulose filter paper increased by 1533%, 2233%, 1567%, and 557% after torrefaction for 40 mins at 200 °C, 220 °C, 240 °C and 260 °C, respectively. Glucose yield decreased with increase in torrefaction severity but after treating torrefied filter samples with alkaline (NaOH) solution, glucose yield increased. For instance, the glucose yield of raw filter paper was 955 mg/g of substrate whereas it was 690 mg/g of substrate for the same filter paper sample torrefied at 200 °C. The glucose yield increased to 808 and 933 mg/g of substrate with 1% and 10% alkaline treatment, respectively.