Structural study of a lead (II) organic complex – a key precursor in a green recovery route for spent lead‐acid battery paste

BACKGROUND: Lead citrate is an attractive precursor for the preparation of ultrafine leady oxide from the paste in spent lead‐acid batteries through a novel hydrometallurgical process, since the recovered lead oxide could be recycled for the production of new lead acid batteries. RESULTS: Two different metal organic complexes were synthesized from lead sulfate from the paste of spent lead‐acid batteries in a leaching solution at two different initial pH values. Single crystals of the two precursors were obtained by conditioning and filtering from the leached solutions, and used for single crystal XRD analysis. At an initial pH of 3.5, the chemical formula of Precursor‐I is deduced to be Pb(C₆H₆O₇)·H₂O while at an initial pH of 5.2, the chemical formula of Precursor‐II is Pb₃(C₆H₅O₇)₂·3H₂O. CONCLUSIONS: Both Precursor‐I and Precursor‐II crystallize in the triclinic crystal system, with space group P‐1. This structural study on precursors sheds light on the mechanism of a paste‐to‐paste recovery route for the recovery of spent lead paste. © 2014 Society of Chemical Industry