Life cycle and environmental cost assessment of ultrasound-assisted alkaline extraction of hemicellulose by sugarcane bagasse pith

Hemicellulose can provide excellent oxygen resistance for packaging film, which is considered to be able to solve the environmental burdens and natural resource consumption problems of traditional petroleum-based packaging. The extraction of hemicellulose from numerous agricultural and forestry wastes, together with its application in packaging materials, has attracted worldwide attention. In this study, the life cycle assessment method was used to qualify the potential environmental impact of ultrasound-assisted alkaline extraction of hemicellulose, including alkali-soluble hemicellulose (AHC) and water-soluble hemicellulose (WHC). The results show that the washing and drying process of AHC extraction and the rotary evaporating together with sedimentation process of WHC extraction are the main contribution of environmental burdens. There are significant differences in ODP, COD, POFP, and NH3–N between AHC and WHC extraction, which are mainly caused by ethanol consumption during the washing and drying process of AHC extraction, while the sedimentation process of WHC extraction moderates the difference trend. From the results of normalization, the environmental implication of WHC is significantly lower than that of AHC. In the utopia scenario, the synergistic effect of ethanol recovery and clean energy substitution can reduce the environmental burdens by 77.4%, and reduce environmental costs by 89%. WHC can be preferred as the raw material of packaging film, but the premise is that the functions of the two kinds of hemicelluloses are consistent. The environmental footprint and cost of hemicellulose extraction process can be further reduced by recycling ethanol and using clean energy, especially in terms of GWP and AP indicators. In this study, quantitative evaluation of environmental profile and environmental cost can provide data support and a fresh perspective on the sustainable development of hemicellulose and biomass refining technology.