Exploration of mechanisms of lignin extraction by different methods

Abstract

Due to a combination of rapid consumption of fossil fuels such as coal and oil with gradual increase in people's awareness of environmental protection, the research for substitute resources has become a hot spot. Because of their abundant sources of raw materials, fast regeneration rate and low greenhouse gas emissions, biomass resources have drawn much attentions. Woody fiber is one of the richest renewable biomass on earth, in which lignin is the largest renewable aromatic compound resource, therefore possessing a very broad application prospect. Nowadays, a large number of reviews on lignin extraction methods have been written while there are few explorations on the mechanisms behind those methods. Thus, the principles of several typical lignin extraction methods were described in this article. These principles were explored with the hope to provide a reference for future development of lignin extraction.

Bio-based platform chemicals synthesized from lignin biorefinery

“…Moreover, aryl ether linkages (mainly related β-O-4 linkages) were broken, and acid-insoluble lignin was recovered in the form of precipitation. 55 It is worth mentioning that the condensation reaction and redeposit on the biomass surface were unavoidable under the batch model, leading to a great modification for extracted lignin. These limitations can be overcome by the sequential extraction (SE) mode because the dissolved lignin is continuously transferred, which is conducive to the preservation of β-O-4 linkages.…”

“…Additionally, the greatest advantage of such a process is the multicomponent component separation of lignocellulose, i.e., lignin, hemicellulose and cellulose. 44,47,58 The common organic solvents for lignin extraction contain methanol, ethanol, acetone, n-butanol, formic acid, methyl isobutyl ketone, isopropanol and H 2 O/organic co-solvents. Concretely, organosolv extraction can be categorized into alcohol-mediated and organic acidmediated extraction.…”

Strategies for lignin depolymerization and reconstruction towards functional polymers

“…In this review, lignin extraction from biomass is not covered because many reviews are available. [26][27][28][29][30][31] Instead, we focus on introducing the chemical and biological depolymerization strategies of lignin and systematically summarize the monomers derived from the lignin biomass and their applications in constructing functional polymers.…”

Advances in the application of molecular sieves as catalysts for lignin depolymerization—HZSM‐5 as an example

“…[13][14][15] However, the unique properties of lignin such as complexity of structure, heterogeneous molecular composition and difficulty in separation, as well as the intricate interlocking structure between cellulose, hemicellulose and lignin enormously hinder the research progress on lignin. 16,17 So far, less than 10% of industrial lignin has been modified and utilized in a high value way. The proper development and utilization of lignin will greatly promote the effective use of renewable resources and further reduce environmental pollution, which is also in line with the principle of green industrialization.…”

“…This makes lignin possessing huge potential value for application 13–15 . However, the unique properties of lignin such as complexity of structure, heterogeneous molecular composition and difficulty in separation, as well as the intricate interlocking structure between cellulose, hemicellulose and lignin enormously hinder the research progress on lignin 16,17 . So far, less than 10% of industrial lignin has been modified and utilized in a high value way.…”