Abstract: N-methyl-pyrrolidone (NMP) is an important solvent for the production of lithium batteries, which causes environmental pollution and wastes resources if it is directly discharged. The current commonly used vacuum distillation recovery process suffers from high operating costs and high energy consumption. Therefore, this paper proposes a coupled pervaporation-adsorption (PV-A) process to recover NMP solvents from lithium battery production waste streams. In this process, pervaporation is used to dewater the NMP waste liquid, it was found that the water content in the raw material liquid decreased from the initial 8.3% (mass) to 0.14% (mass) after 400 min of dewatering, but the membrane separation performance decreased significantly when the water content of the raw material liquid decreased to 0.45% (mass), and at the same time, the NMP loss rate increased rapidly. An adsorption process was used to remove trace water from the remaining liquid, and the water content in the feed liquid under the optimal adsorption process conditions was reduced from 0.45% (mass) to 0.014%, which fully meets the purity requirements of electronics-grade NMP for the production of lithium batteries. Steady-state modeling and techno-economic evaluation of the proposed coupled process were carried out, and compared with vacuum distillation and pervaporation technologies, the results showed the PV-A process yielded the best techno-economic performance and the lowest environmental impact, and it can be used as an alternative process to the traditional NMP recycling technology. This study provides a new method for the recycling of NMP in the lithium battery industry.

Key words: Pervaporation, NaA zeolite membrane, Adsorption, NMP recovery, Techno-economic evaluation

摘要： N-methyl-pyrrolidone (NMP) is an important solvent for the production of lithium batteries, which causes environmental pollution and wastes resources if it is directly discharged. The current commonly used vacuum distillation recovery process suffers from high operating costs and high energy consumption. Therefore, this paper proposes a coupled pervaporation-adsorption (PV-A) process to recover NMP solvents from lithium battery production waste streams. In this process, pervaporation is used to dewater the NMP waste liquid, it was found that the water content in the raw material liquid decreased from the initial 8.3% (mass) to 0.14% (mass) after 400 min of dewatering, but the membrane separation performance decreased significantly when the water content of the raw material liquid decreased to 0.45% (mass), and at the same time, the NMP loss rate increased rapidly. An adsorption process was used to remove trace water from the remaining liquid, and the water content in the feed liquid under the optimal adsorption process conditions was reduced from 0.45% (mass) to 0.014%, which fully meets the purity requirements of electronics-grade NMP for the production of lithium batteries. Steady-state modeling and techno-economic evaluation of the proposed coupled process were carried out, and compared with vacuum distillation and pervaporation technologies, the results showed the PV-A process yielded the best techno-economic performance and the lowest environmental impact, and it can be used as an alternative process to the traditional NMP recycling technology. This study provides a new method for the recycling of NMP in the lithium battery industry.

关键词: Pervaporation, NaA zeolite membrane, Adsorption, NMP recovery, Techno-economic evaluation