关键词: 碘化锂, 复分解电渗析, 清洁生产, 离子交换膜

Abstract: Lithium iodide, an important raw material for synthesizing lithium battery electrodes, is in increasing demand with the continuous expansion of the new energy market. The current preparation process of lithium iodide requires hazardous chemicals such as biphenylamine and sulfureted hydrogen, which limits its large-scale application. Therefore, finding an environmentally friendly and efficient process for preparing lithium iodide is crucial. In this work, lithium sulfate was used as the lithium source, and electrodialysis metathesis (EDM) was used to cleanly prepare lithium iodide. The effects of the operating voltage, the initial volume ratio of the product liquid to the feed liquid, and the initial feed concentration on the EDM were investigated, and the process was analysed economically. The experimental results showed that increasing the operating voltage can shorten the process time; decreasing the initial volume ratio can significantly improve the concentration of lithium iodide, but the current efficiency will decrease; increasing the initial feed concentration can significantly improve the concentration of lithium iodide and enhance the capacity of the system. Under the conditions of a voltage of 25 V, an initial volume ratio of 1:1, and initial potassium iodide and lithium sulfate concentrations of 0.2 mol/L and 0.1 mol/L, respectively, lithium iodide was prepared with a purity of up to 98.8%, and the cost of the process was approximately 3.6 ￥/kg LiI. The electrodialysis metathesis process for the preparation of lithium iodide is economically feasible and has great potential for industrialization. This indicates that the preparation of lithium iodide by EDM has the advantages of simplicity, low energy consumption, and environmental friendliness and is of reference significance for realizing the green scale preparation of lithium iodide.

Key words: lithium iodide, electrodialysis metathesis, clean production, ion exchange membrane