Lignin enhances cellulose dissolution in cold alkali

Carolina Costa; Bruno Medronho; Alireza Eivazi; Ida Svanedal; Björn Lindman; Håkan Edlund; Magnus Norgren

doi:10.1016/j.carbpol.2021.118661

Lignin enhances cellulose dissolution in cold alkali

Carbohydr Polym. 2021 Nov 15:274:118661. doi: 10.1016/j.carbpol.2021.118661. Epub 2021 Sep 10.

Authors

Carolina Costa¹, Bruno Medronho², Alireza Eivazi³, Ida Svanedal⁴, Björn Lindman⁵, Håkan Edlund⁶, Magnus Norgren⁷

Affiliations

¹ FSCN, Surface and Colloid Engineering, Mid Sweden University, SE-85170 Sundsvall, Sweden. Electronic address: carolina.costa@miun.se.
² FSCN, Surface and Colloid Engineering, Mid Sweden University, SE-85170 Sundsvall, Sweden; MED - Mediterranean Institute for Agriculture, Environment and Development, Faculty of Sciences and Technology, University of Algarve, Campus de Gambelas, Ed. 8, 8005-139 Faro, Portugal. Electronic address: bfmedronho@ualg.pt.
³ FSCN, Surface and Colloid Engineering, Mid Sweden University, SE-85170 Sundsvall, Sweden. Electronic address: alireza.eivazi@miun.se.
⁴ FSCN, Surface and Colloid Engineering, Mid Sweden University, SE-85170 Sundsvall, Sweden. Electronic address: ida.svanedal@miun.se.
⁵ Physical Chemistry, University of Lund, P.O. Box 124, S-221 00 Lund, Sweden; Coimbra Chemistry Center (CQC), Department of Chemistry, University of Coimbra, Rua Larga, 3004-535 Coimbra, Portugal. Electronic address: bjorn.lindman@fkem1.lu.se.
⁶ FSCN, Surface and Colloid Engineering, Mid Sweden University, SE-85170 Sundsvall, Sweden. Electronic address: hakan.edlund@miun.se.
⁷ FSCN, Surface and Colloid Engineering, Mid Sweden University, SE-85170 Sundsvall, Sweden. Electronic address: magnus.norgren@miun.se.

PMID: 34702480
DOI: 10.1016/j.carbpol.2021.118661

Abstract

Aqueous sodium hydroxide solutions are extensively used as solvents for lignin in kraft pulping. These are also appealing systems for cellulose dissolution due to their inexpensiveness, ease to recycle and low toxicity. Cellulose dissolution occurs in a narrow concentration region and at low temperatures. Dissolution is often incomplete but additives, such as zinc oxide or urea, have been found to significantly improve cellulose dissolution. In this work, lignin was explored as a possible beneficial additive for cellulose dissolution. Lignin was found to improve cellulose dissolution in cold alkali, extending the NaOH concentration range to lower values. The regenerated cellulose material from the NaOH-lignin solvents was found to have a lower crystallinity and crystallite size than the samples prepared in the neat NaOH and NaOH-urea solvents. Beneficial lignin-cellulose interactions in solution state appear to be preserved under coagulation and regeneration, reducing the tendency of crystallization of cellulose.

Keywords: Cellulose amphiphilicity; Dissolution; Lignin; NaOH (aq.) solvent.