Valorization of straw biomass into lignin bio-ink, bacterial cellulose and activated nanocarbon through the trade-off alkali-catalyzed glycerol organosolv biorefinery

Abstract

Integrated lignocellulosic biorefinery that transforms low-value lignocellulose into multiple value-added products is crucial for a low-carbon sustainable development. Herein, a one-pot alkali-catalyzed glycerol organosolv (ALGO) pretreatment-based integrated biorefinery process to directionally produce lignin bio-inks, bacterial celluloses (BCs), and activated nanocarbons (ANCs) was proposed. ALGO pretreatment could modify the structure of dissolved lignins by glycerolysis. The extracted lignin fragments with high-purity (>90 %), uniform with low molecular weight (2500–4000 of Mw), and abundant hydrophilic aliphatic –OH were promising candidates in 3D-printable inks preparation. The glycerolysis reaction during ALGO process also enabled pretreated substrates toward high hydrolyzability and protected pretreatment liquor from generating fermentable inhibitors, making the solid fractions more liable for enzymatic deconstruction and microbial fermentation. Without any detoxification treatments, hydrolysates from ALGO pretreated substrates were used directly as carbon sources for BCs production, resulting in the BC yields were 56 % higher than that of the commercial glucose. The enzymatic hydrolysis residue and BC fermentation waste liquid were synthesized into ANCs via a facile carbonization process, which could further increase the value of ALGO biorefinery. Calculations showed that this ALGO integrated strategy rendered the conversion of ∼75 % lignins in pretreatment liquor to bio-inks and nearly 100 % solid fractions to BCs and ANCs. Unlike the conventional “lignin-first” route to obtain high-purity cellulose by sacrificing the value-adding conversion ability of by-products, the designed technical route in this work achieved a good trade-off between fractionation ability and subsequent conversion potential, inspiring further exploration of the technical correlation between biomass fractionation and bioproduct processing.