High-value Utilization of Wood Vinegar and Its Environmental Benefit Analysis

To achieve efficient utilization of wood vinegar, this study proposed an organic solvent extraction process, in which the extract phase was used for phenol recovery, while the raffinate phase underwent anaerobic digestion for methane production, and untreated wood vinegar was recorded as AS. A life cycle assessment(LCA) was conducted to evaluate the environmental impact of this process in industrial application. The results showed that dichloromethane(DCM), diethyl ether(Et2 O), and ethyl acetate (EtOAc) extract effectively retained the volatile fatty acids(VFA) in wood vinegar, with dichloromethane performing the best, followed by ethyl acetate. The extract phase was enriched with phenolic compounds, primarily phenol, with ethyl acetate achieving the highest enrichment. Mesophilic anaerobic digestion experiments revealed that untreated wood vinegar had a methane production potential(chemical oxygen demand(COD) mass meter) of 41. 92 L/kg. After extraction with dichloromethane and ethyl acetate, methane production potential increased to 65. 83 L/kg and 66. 21 L/kg of the extract residue phase AS-DCM and AS-EtOAc, respectively, whereas diethyl ether extraction(AS-Et2 O) reduced methane potential. LCA analysis indicated that adding an ethyl acetate extraction unit reduced environmental impacts in terms of ecological toxicity potential, eutrophication potential, and global warming potential. The data for these three metrics are only 67%, 79% and 60% of the original process, respectively, achieving the lowest overall impact. In contrast, diethyl ether increased negative impacts of the process. In conclusion, dichloromethane and ethyl acetate are recommended extractants to enhance methane production. For ecological benefits, ethyl acetate is the optimal choice.