Synthesis of nanosized powders for lead-acid battery pastes by recycling of used batteries

In the present work we have investigated the oxysulfate fraction of spent lead-acid battery pastes in search of an optimal method for its recycling. For this purpose, desulfurization and leaching were performed in one step by adding simultaneously sodium citrate and citric acid at varying temperatures (25-100^оС) and heat treatment times (1-2h) in order to obtain a lead-citrate precursor for direct application in the production of lead oxide powder. Two types of lead citrate were obtained, (Pb(C₆H₅O₇)₂.H₂O and Pb₃(C₆H₅O₇)₂.3H₂O). After calcination at low temperature (300^oC), these precursors form a nanosized lead oxide powder. X-ray diffraction analysis (XRD) was performed at each stage of the study to monitor the changes in phase composition and crystallite size of the synthesized powder. Morphological features were investigated by scanning electron microscopy (SEM). An additional differential thermal analysis (DTA) was performed to determine the type of the obtained lead citrate. Finely dispersed lead oxide powders are formed. The measured crystallite sizes of the two main phases are: β-PbO₍₁₁₁₎ – 30-50nm and Pb₍₁₁₁₎ – 40 - 60nm, respectively.