Pyrolysis and Extraction of Bark in a Biorefineries Context: A Critical Review

Abstract

Bark-based biorefineries are estimated to become a trending topic in the coming years, particularly with their adsorbent applications and antioxidant production. While the potential benefits of bark-based biorefineries are well-recognized, it is not known how to develop a bark-based biorefinery considering different unit operations and the potential end products. The characterization and screening of different barks for chemical composition is the initial step in biorefinery development, along with the selection of the relevant conversion processes. This state-of-the-art review provides background knowledge on the pyrolysis and extraction studies of bark as the key conversion operations. The results of recent (2010–2022) bark pyrolysis and extraction studies were critically analyzed for process conditions, product properties, and product yields, as well as a discussion of energy-saving possibilities. A biorefinery scheme was proposed based on these data. The current knowledge gaps were identified and future directions were evaluated, which include the production of charcoals, platform chemicals, and extract profiling for specific applications. The results indicate that barks are particularly rich in hydrophilic extractives with potential antioxidant properties and pyrolysis operations, resulting in functional chars that may be used in value-added applications as adsorbent materials. A biorefinery scheme allows for the production of platform chemicals, antioxidant extracts and biochars from barks while contributing to the reduction of waste and environmental pollution.

Maceration of Waste Cork in Binary Hydrophilic Solvents for the Production of Functional Extracts

“…The high extractive content is a distinctive property of tree bark [36]. The hydrophilic fraction is possibly the most important fraction of the bark extracts, which shows a large variation among different barks [37]. The Q. cerris waste cork contains up to 6.6% hydrophilic extractives, while in Q. cerris phloem, this value is about 4.1% [5].…”

“…Tree barks are increasingly considered for the production of antioxidant and antimicrobial agents, and different barks were analyzed [37]. The analyzed barks are usually locally available barks, and they show promising antioxidant and antimicrobial properties [41,43,44].…”

Properties of Bark Particleboard Bonded with Demethylated Lignin Adhesives Derived from <i>Leucaena leucocephala</i> Bark

“…Environmental considerations are vital in bark particleboard manufacturing to ensure sustainability and eco-friendliness. Bark particleboard utilizes bark as a raw material, reducing waste and maximizing resource use [10]. Adhesive selection should prioritize environmentally friendly options with low formaldehyde emissions or formaldehyde-free formulations [11].…”