复分解电渗析清洁制备碘化锂实验研究

Clean production of lithium iodide by electrodialysis metathesis

碘化锂广泛应用在燃料电池的合成中,目前碘化锂的生产方式主要有联氨法和硫化氢还原法,制备过程中需使用联胺或硫化氢,这些均属于危险化学品,存在较大安全风险,制约它的工业化生产。本工作以初级锂盐硫酸锂为原料,采用复分解电渗析清洁制备碘化锂,研究了操作电压、产品液与原料液初始体积比和原料液初始浓度对制备过程的影响,并对碘化锂产品与制备过程进行评价与经济性分析。实验结果表明,提高操作电压可以缩短反应时间;降低产品液与原料液初始体积比可以明显提升碘化锂产品浓度,但电流效率会下降;增加初始原料液浓度可以显著提升碘化锂产品的浓度,提升系统的产能。在操作电压为25 V,初始碘化钾浓度为0.2 mol/L,初始硫酸锂浓度为0.1 mol/L,产品液与原料液初始体积比为1:1的条件下,制备的碘化锂产品纯度可达98.8%,工艺过程成本约为3.6¥/kg LiI。复分解电渗析制备碘化锂具有工艺流程简单、能耗低、环境友好等明显优势,这对电驱动膜分离在锂盐清洁生产的应用具有重要参考意义。

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.