Rapid and Direct Preparation of Lignin Nanoparticles from Alkaline Pulping Liquor by Mild Ultrasonication

Melissa B. Agustin*, Paavo A. Penttilä, Maarit Lahtinen, Kirsi S. Mikkonen

*Corresponding author for this work

Research output: Contribution to journalArticleScientificpeer-review

11 Citations (Scopus)
9 Downloads (Pure)

Abstract

The production of lignin nanoparticles (LNPs) has opened new routes to the utilization of lignin in advanced applications. The existing challenge, however, is to develop a production method that can easily be adapted on an industrial scale. In this study, we demonstrated a green and rapid method of preparing LNPs directly from a sulfur-free alkaline pulping liquor by combining acid precipitation and ultrasonication. The combined method produced spherical LNPs, with a hierarchical nanostructure and a highly negative surface charge, within only 5 min of sonication. The mild, rapid sonication was achieved by sonicating directly without prior drying of the acid-precipitated and dialyzed lignin. Optimization of the method revealed the potential for minimizing acid consumption, shortening the dialysis time, and processing directly the alkaline liquor with as much as 20 wt % lignin. The isolated LNPs were stable during storage for 180 days, at a pH range of 4-7, and in a dispersing medium below 0.1 M NaCl. The LNPs also displayed excellent emulsifying properties, stabilizing oil-in-water emulsions. Thus, this simple and energy-efficient method opens a sustainable, straightforward, and scalable route to the production of organic solvent-free LNPs, with high potential as interface stabilizers of multiphase systems in the food and medical industries.

Original languageEnglish
Pages (from-to)19925 − 19934
JournalACS Sustainable Chemistry and Engineering
Volume7
Issue number24
DOIs
Publication statusPublished - 2019
MoE publication typeA1 Journal article-refereed

Keywords

  • acid precipitation
  • alkaline pulping liquor
  • BLN lignin
  • emulsion
  • lignin nanoparticle
  • ultrasonication

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