Synthesis, modification and application of nano structured ultra fine lead (II) oxide from spent automobile lead acid battery

Abstract

Toxic wastes such as lead slag, mattes, acidic sludge, particulates and emission of airborne gases are major industrial wastes associated with lead acid battery industries. The aim of this study is to develop a novel and environmentally sound route that avoids smelting of the paste to recover Pb in form of PbO in nano-sized range. The wastes contained different percentages of impurities depending on the sources of the waste. 62%wt of Pb was found with Cd, Ag, As, Co, Cr, Cu, Fe, Mn, Ni, Sb, Se, Te ranging from nf-0.037%wt in the paste Hydrometallurgical alternative is effective in recovery and treatment of the waste because of it numerous advantages. Suitable leaching and precipitating agents were employed to achieve the recovery at pre-determined pH and further processes were undertaken to produce secondary raw materials (nano- Materials) for industrial use. In this research, different organic acids; citric acid, acetic acid and formic acids were selectively optimized to choose the acid with maximum leaching/precipitation potentials. Citric acid was found having highest recovery of over 98%, formic acid 81% and acetic acid with 61% for the recovery of lead. Optimization conditions for this research were arrived at after several parameters optimization. 1M citric acid, 2M Sodium citrate and 2M hydrogen peroxide was found suitable (excess of citric acid & hydrogen peroxide in appropriate ratio), 100g/L S/L, 180 minute reaction time, 500rpm, and 30oC. Lead citrate precursor for the production of PbO was characterized by XRD, SEM/ EDX, FT-IR. The lead precipitate calcination temperature was determined by TG-DTA to be 400oC and the product of calcination/combustion was characterized by XRD, SEM/ EDX, FTIR for structural and material elucidation. The final product was found to be combination of α-PbO and β-PbO with particle size ranging between 60-300nm. The results of kinetic studies of leaching/precipitating in citric acid medium revealed ash diffusion control dense constant size spherical particles model as the experimental datat fitted satisfactorily with the equation 1-3(1-X)2/3+2(1-X) for the battery paste. The product in this work could serve as starting material in the production of a new lead acid battery and this novel route provided environmentally sound method of recovery Pb from spent lead acid batteries.