Sonochemistry: What Potential for Conversion of Lignocellulosic Biomass into Platform Chemicals?

Abstract

This Review focuses on the use of ultrasound to produce chemicals from lignocellulosic biomass. However, the question about the potential of sonochemistry for valorization/conversion of lignocellulosic biomass into added-value chemicals is rather conceptual. Until now, this technology has been mainly used for the production of low-value chemicals such as biodiesel or as simple method for pretreatment or extraction. According to preliminary studies reported in literature, access to added-value chemicals can be easily and sometimes solely obtained by the use of ultrasound. The design of sonochemical parameters offers many opportunities to develop new eco-friendly and efficient processes. The goal of this Review is to understand why the use of ultrasound is focused rather on pretreatment or extraction of lignocellulosic biomass rather than on the production of chemicals and to understand, through the reported examples, which directions need to be followed to favor strategies based on ultrasound-assisted production of chemicals from lignocellulosic biomass. We believe that ultrasound-assisted processes represent an innovative approach and will create a growing interest in academia but also in the industry in the near future. Based on the examples reported in the literature, we critically discuss how sonochemistry could offer new strategies and give rise to new results in lignocellulosic biomass valorization.

Sonocatalysis: A Potential Sustainable Pathway for the Valorization of Lignocellulosic Biomass and Derivatives

“…Ultrasonic energy can have a direct influence on hydrolysis and fermentation reactions of cellulosic materials, while the application of ultrasound with enzymes accelerates saccharification and the fermentation rate [36]. Cavitation effects enhance the transport of enzyme macromolecules to the surface of the substrate, whereas the substrate surface is opening up to the action of enzymes due to the mechanical effect of cavitation [4, 62]. Additionally, the sono-assisted enzymatic conversion of cellulose performed in solvents such as ionic liquids (ILs) yielded high performances by promoting high conversion, yield, and selectivity [36].…”

“…In order to scale up the oxidation of cellulose, Paquin et al [77] proposed the use of a continuous flow-through system instead of the classical standard batch mode. The flow-through reactor increased the reaction rate (~36%) in comparison to the batch reactor while decreasing the overall energy consumption (~87%) [4]. …”

“…Nevertheless, plant dry matter possesses a sturdy structure, which complicates the effective conversion process of lignocellulosic biomass into platform chemicals. Lignocellulose is a recalcitrant biopolymer composed of the semi-crystalline polysaccharide cellulose, the polysaccharide hemicellulose, and the three-dimensional amorphous phenylpropanoid lignin polymer [4, 5]. The conversion of lignocellulosic feedstock leads to the production of a variety of added value platform chemicals, including phenolic compounds ( p -coumaryl alcohol, coniferyl alcohol, and sinapyl alcohol), aliphatic acids (formic acid, acetic acid, levulinic acid), and furan aldehydes (hydroxymethyl furfural) [6].…”

“…Over the past few years, research on the development and optimization of highly active and selective catalytic systems has been an ongoing activity to overcome drawbacks associated with harsh chemical conditions, low yield production, and high processing cost [18]. Additionally, sonochemical-assisted reactions offer opportunities to develop environmentally friendly and cost-effective processes for biomass upgrading [4, 19]. …”

Study of Acid Hydrolysis on Organic Waste: Understanding The Effect of Delignification and Particle Size

“…It is necessary to separate the complex components of lignocellulose which consider the compatibility of feedstocks, enzymes, and organisms. The pretreatment process generally can be classified into physical [21], chemical [22], physical-chemical, biological methods and their combinations.…”