本工作采用摩尔比为1:2的氯化胆碱-乙二醇低共熔溶剂(ChCl-EG DES)作为电解质,研究了对废旧铅酸蓄电池铅膏(Scrap Lead Paste, SLP)进行电解回收制备铅粉。通过循环伏安法探讨了30 g/L SLP+ChCl-EG体系中沉积铅的电化学行为,采用XRD和SEM检测手段分析了不同温度下沉积产物的物相和微观形貌。结果表明,废铅膏在ChCl-EG中还原为金属铅是一个受扩散控制的准可逆过程,恒电位沉积实验发现,当实验温度为363 K时,电流效率达96.06%,电能单耗为673.28 kWh/t。不同温度下电沉积得到的产物均为金属铅粉,其微观形貌主要为棒状,有少量呈现针状、团簇状,长度约为10~60 μm,直径<5 μm。
As a clean energy source without pollution during use, lead-acid batteries have received close attention. However, lead-acid batteries contain a large amount of polluting heavy metals, and random disposal will pollute the environment and affect the ecological balance. In industry, the recovery of scrap lead paste (SLP) is usually treated by pyrotechnics, but it consumes a lot of energy and also produces pollutants such as sulfur dioxide and lead dust. In view of the existing problems, finding new recycling processes has become a research hotspot. Deep eutectic solvents (DESs) are a new generation of green solvents and have received more and more attention in recent years. Because of their good thermal stability and wide electrochemical window, DESs are widely used in the fields of metal extraction and material preparation. In this work, the recycling of scrap lead paste to prepare lead powders by electrolysis is discussed in choline chloride-ethylene glycol deep eutectic solvent (ChCl-EG DES). Firstly, the phase composition of the scrap lead paste is analyzed by XRD, and the quantitative analysis of the scrap lead paste using Jade software shows that it mainly exists in the form of lead dioxide with a small amount of lead sulfate at the same time. And then, the electrochemical behavior of lead ion in 30 g/L SLP+ChCl-EG solution is investigated by cyclic voltammetry. The phase composition and microscopic morphology of the deposit product at different temperatures are examine using XRD and SEM techniques. The experimental results show that when scrap lead paste is added, Pb(IV) can be reduced preferential to Pb(II) due to the reducibility of ChCl-EG DES. Cyclic voltammetry indicates that the reduction of scrap lead paste to metal lead is a quasi-reversible process in ChCl-EG DES. The constant voltage deposition experiment show that when the temperature rises from 323 K to 363 K, the current efficiency rises from 67.26% to 96.06% and the specific energy consumption decreases from 961.57 kWh/t to 673.28 kWh/t. XRD and SEM results demonstrate that the deposit products obtained at different temperatures are pure metallic lead powders and their microscopic morphology are mainly rod-shaped and slight acicular.