Optimization of the methodology for lead extraction from waste contaminated with heavy metals

Abstract

A sequential experimental design strategy is used to optimize the extraction of lead from slag. The slag is composed mainly of iron (= 60%) and lead (= 6%), and cannot be disposed of in conventional landfill due to its high lead content. The extraction of lead is based on the complexing properties of ethylenediaminetetra-acetic acid (EDTA), the iron being masked with fluoride ions. Atomic absorption spectroscopy (AAS) has been used for monitoring iron and lead concentrations. In a first step, Plackett-Burman PB-12 experimental design was used for screening the variables and for selecting those to be used. Two central composite designs (CCDs) were then carried out to determine the optimal conditions for lead extraction. The optimized experimental conditions were established to be: contact time with the fluoride solution 30 min; particle size of slag between 150 and 600 microm; molecular concentration of fluoride solution 2.4 x 10(-3) mol and of EDTA 5 x 10(-4) mol; pH 1.5; 8 h contact time with the EDTA solution; and temperature 60 degrees C. Under these experimental conditions the lead content was reduced by 57% compared with the raw sample.

Preparation of Lead, Lead Alloy(S) And Other Salts from Exhausted Rechargeable Lead Batteries

“…It can be seen that with and the same metal ion concentration in the solution, the Kd value increases with the decrease in concentration. This statement is logic as given in equation (2). The value of the denominator decreases that gives a corresponding increase in Kd value.…”

“…It reduces water consumption over life of battery, it also reduces electrolyte & hydrogen gas evolution. Better selfdischarge characteristics-(typically .05% per day at 25°C) is attained with this alloy together with stable rate under float charge over the life of the battery and constant current draw [2] Chen et al [3] repor4ted recovery of lead from fly ash of waste lead-acid batteries. The lead salt is lead sulphate (PbSO4) and lead oxy sulphate (Pb2OSO4).…”

Optimization of marine waste based-growth media for microbial lipase production using mixture design methodology

“…Generally, the mixture design method has been used to study relationships among proportions of different variables and responses. It is able not only to establish the surface model of continuous variables, estimating the effect of each element in the mixture and their interactions on the response, but can also optimize elemental composition according to the target [24,25].…”