title: 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.
authors.affiliation: Department of Chemistry, Universidade Regional Integrada (URI), Erechim, Brazil.
authors.forename: Alessandra
authors.initials: A
authors.lastname: Smaniotto
authors.forename: Angela
authors.initials: A
authors.lastname: Antunes
authors.forename: Irajá Do
authors.initials: ID
authors.lastname: Nascimento Filho
authors.forename: Luciana Dornelles
authors.initials: LD
authors.lastname: Venquiaruto
authors.forename: Débora
authors.initials: D
authors.lastname: De Oliveira
authors.forename: Altemir
authors.initials: A
authors.lastname: Mossi
authors.forename: Marco
authors.initials: M
authors.lastname: Di Luccio
authors.forename: Helen
authors.initials: H
authors.lastname: Treichel
authors.forename: Rogerio
authors.initials: R
authors.lastname: Dallago
mesh_terms: D002614:Chelating Agents / Q000737:chemistry*; D004492:Edetic Acid / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007220:Industrial Waste; D007854:Lead / Q000302:isolation & purification*; D018505:Waste Management / Q000379:methods*
chemical_list: D002614:Chelating Agents; D007220:Industrial Waste; D007854:Lead; D004492:Edetic Acid