A closed-loop acetic acid system for recovery of PbO@C composite derived from spent lead-acid battery

The current hydrometallurgical recovery routes of spent lead paste generate a large amount of acid/alkali re-sidual filtrate, bringing significant technical and environmental challenge. In this study, the low-impurity lead acetate solution was prepared by reacting desulfurized paste with acetic acid (HAc), which then reacted with citric acid to synthesize high-quality lead citrate. Further crystallizing lead citrate into larger size enhanced the filtration and separation performance. The filtrate containing 95% dose of HAc could be recirculated for leaching the next batch of desulfurized paste, so a closed-loop process of leaching reagent was realized. The leady oxide comprising carbon (PbO@C) composite was synthesized via calcination of lead citrate. Compared with the traditional lead-acid battery, the novel lead-carbon battery made of PbO@C composite showed better electro-chemical performance. The green recovery process of spent lead paste proposed in this research provided a sustainable strategy to recover secondary lead via a closed-loop route.