NADES-based fractionation of biomass to produce raw material for the preparation of cellulose acetates

Abstract

Waste biomass (agave bagasse) and native birch wood were used as raw materials for a novel fractionation and derivation process to produce cellulose acetates (CAs). During the first stage of the fractionation process, a significant amount of hemicelluloses and lignin were dissolved from the biomass using a natural deep eutectic solvent (NADES) that consisted of a mixture of choline chloride and lactic acid with the molar ratio of 1:9. Then, the residual solid material was delignified by bleaching it with a mixture of acetic acid and sodium chlorite. The fractionation process generated differently purified pulps (celluloses) which were converted to CAs. The crystallinity index, polymerization degree, chemical composition, and thermal properties of the differently purified pulps and CAs were analyzed to evaluate the efficacy of the acetylation process and to characterize the CAs. The chemical derivation of the differently purified cellulose samples generated CAs with different degrees of substitution (DSs). The more purified the cellulose sample was, the higher its DS was. Moreover, some differences were observed between the acetylation efficiencies of birch and agave bagasse. Typically, cellulose purified from birch by treating it with NADES followed by bleaching was acetylated more completely (DS = 2.94) than that derived from agave bagasse (DS = 2.45). These results revealed that using green solvents, such as NADES, to treat both agave bagasse (waste biomass) and birch wood, allowed pure fractions to be obtained from biomass, and thus, biomass could be valorized into products such as CAs, which present a wide range of applications.

Cellulose Membranes in the Treatment of Spent Deep Eutectic Solvent Used in the Recovery of Lignin from Lignocellulosic Biomass

“…Lignin has a very complex structure, and it is difficult to dissolve from lignocellulosic biomass [11]. DESs have been actively studied as solvents for lignocellulosic biomass treatment [12][13][14][15][16] because they demonstrate dissociation abilities towards aryl ether bonds and carbon-carbon bonds as well as towards lignin-carbohydrate complex [17].…”

Cellulose Nanofibers Derived Surface Coating in Enhancing the Dye Removal with Cellulosic Ultrafiltration Membrane

“…A slightly higher intensity of the peak at 1730 cm −1 indicates that the CNFs-coated membrane have more carboxyl groups than the pristine regenerated cellulose membrane. This could be explained by the presence of residual lactic acid from DES-based defibrillation process, or by the acetylation of a small fraction of the CNFs [38]. The spectra of the CNFs-coated membrane showed a lower intensity of the -OH groups, commonly expressed in the peaks at 3350 cm −1 and 1000 cm −1 characteristic of cellulose [38] which would be consistent with the shallowed superior content of carbonyl groups in the CNFs coating.…”

Esterified Lignin from Construction and Demolition Waste (CDW) as a Versatile Additive for Polylactic‐Acid (PLA) Composites—The Effect of Artificial Weathering on its Performance

“…In addition to the commercial additives, lignin‐based materials from two different sources (native birch wood and CDW that was based mainly on softwood) were used as additives in the composites. Lignin extraction from both native and CDW wood has been described in previous publications [ 20 , 21 ] and the lignin recovered from wood with DES has here been called “DES‐lignin”. Briefly, DES solution (1:9 choline chloride: lactic acid) was used as the solvent for lignin extraction.…”