Utilization of Waste Leather for Efficient Removal of Ca2+ and Mg2+ via Nano-structural Adsorption in Lithium Carbonate Production

Abstract

Pengxiang Zhao*a, b Jianyu Weic, Fumei Wangd, Yang Luob Luming Yanga* With the growth of electric vehicles (EVs), the demand for battery grade lithium carbonate (Li₂CO₃) is increasing significantly. However, large part of the Li₂CO₃ is industrial-grade which cannot be satisfied with the preparation of cathode, either ternary material or lithium iron phosphate (Li₂CO₃ is one of the precursors for either ternary material or lithium iron phosphate). Traditional production involves converting industrial-grade lithium carbonate into LiHCO₃ solution through carbonization by using CO₂. The insoluble impurities are removed by filtering followed by thermal decomposition to produce battery-grade Li₂CO₃. However, Ca2+ and Mg2+ are the most difficult impurities to remove due to the similar behavior with Li+. This study evaluates using vegetable-aldehyde combination tanned leather to filter Ca²⁺ and magnesium Mg²⁺ ions from LiHCO₃ solution via the nano structure of the leather. The results show effective reduction of Ca²⁺ and Mg²⁺ concentrations from LiHCO₃ solution. Treated with EDTA, the leather can be reused for at least 12 cycles, that ensure the high-quality lithium carbonate production cost-effectively and sustainably. The study highlights the tanned leather's potential as a reliable filtration medium for lithium-ion battery precursors.