Comparison of life cycle assessment between lyocell fiber and viscose fiber in China.

Purpose: The purpose of this study is to analyze the environmental impact of the viscose fiber/lyocell fiber manufacturing industry and obtain improvement information from China's analysis results. Our main research question is: How will the production of viscose/lyocell fiber affect the environment? Which raw material or process has the most significant impact on the environment? Is it possible for lyocell fiber to replace viscose fiber that has a greater impact on the environment? Methods: For the life cycle assessment (LCA) method, we use the analysis from the raw materials (pulp) to the end of the production (fiber) process. The paper mainly introduces the water consumption, energy utilization, and the production of three industrial wastes in producing the two fibers. The life cycle inventory input and output data were collected from two fiber manufacturers in China (manufacturing viscose fiber and lyocell fiber, respectively). Six impact categories were calculated using eFootprint online platform, including primary energy consumption (PED), non-living resource consumption potential (ADP), Resource depletion–water (WU), global warming potential (GWP), acidification potential (AP), and ecotoxicity (ET). Results and discussion: There is no significant difference between the ADP and WU values of the two processes from a comprehensive comparison. In PED, the value of lyocell fiber is approximately three times that of viscose fiber. Because viscose fiber uses more sulfide; its AP value is about twice that of lyocell fiber. The GWP of lyocell fiber is about two of that of viscose fiber. The ET value of viscose fiber is an order of magnitude higher than that of lyocell fiber. In the viscose fiber process, steam, pulp, ZnSO₄, and sulfuric acid are the main contributors to the process's environmental impact. The main contribution rates of steam to PED, WU, GWP, and AP are 23.6%, 16.76%, 43.33%, and 18.99%, respectively. The use of ZnSO₄ in viscose fiber resulted in an ET value of more than 90%. Alternatives can be found to reduce the environmental impact further. It is of great significance to study materials that can replace ZnSO₄ as additives. In the lyocell fiber process, electricity, pulp, and steam are the main contributors to the process. The main contribution rates of electricity to PED, ADP, GWP, AP, and ET are 57.5%, 62%, 51%, 59.9%, and 69.3%, respectively. At present, this process mainly uses thermal power generation, which makes the environmental impact caused by electricity consumption great. If more economical or cleaner power supply can be considered, the environmental impact will be further improved. [ABSTRACT FROM AUTHOR]