Leaching of lead by ammonium salts and EDTA from Salvinia minima biomass produced during aquatic phytoremediation.
Plant biomass harvested after heavy-metal phytoremediation must be considered as a hazardous waste that should be contained or treated appropriately before disposal or reuse. As a potential method to detoxify the biomass and to convert this material to a suitable fertilizer or mulch, leaching of lead (Pb) from Salvinia minima biomass was studied by testing water, several aqueous ammonium salts, and EDTA solution as lead extractants. The research was carried out in two phases: (i) a leaching study to determine the lead-extraction efficiency of the different leachants, and (ii) a thermodynamic analysis to identify the likely reactions and stable Pb(II) species formed in the leaching systems of the most efficient leachants. Experimentally, lead concentrations measured in leached biomass and in leachates were significantly different among the various leachants. It was determined that the extraction strength of the leachants followed the order: EDTA>ammonium oxalate>water approximately ammonium nitrate>ammonium acetate, achieving Pb extraction efficiencies of 99%, 70%, 7.2%, 6.9% and 1.3%, respectively, in single-stage extractions. The thermodynamic study indicated that the dominant species produced by the leaching process should be the soluble species PbEDTA2- for EDTA system, and the insoluble Pb(COO)2S precipitate for the oxalate system.
Núñez-López
Roberto Aurelio
RA
Centro de Investigación y Desarrollo Tecnológico en Electroquímica (CIDETEQ), Parque Tecnológico Querétaro, Sanfandila, Pedro Escobedo Qro., 76700 Mexico, Mexico. ndahi2000@yahoo.com
Meas
Yunny
Y
Gama
Silvia Citlalli
SC
Borges
Raúl Ortega
RO
Olguín
Eugenia J
EJ
D000085:Acetates / Q000737:chemistry; D001673:Biodegradation, Environmental; D018533:Biomass; D002614:Chelating Agents / Q000737:chemistry*; D004492:Edetic Acid / Q000737:chemistry*; D029624:Ferns / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D007854:Lead / Q000737:chemistry*; D009566:Nitrates / Q000737:chemistry; D010070:Oxalates / Q000737:chemistry*; D012989:Soil Pollutants / Q000737:chemistry*; D013816:Thermodynamics
D000085:Acetates; D002614:Chelating Agents; D009566:Nitrates; D010070:Oxalates; D012989:Soil Pollutants; D007854:Lead; D004492:Edetic Acid; C018824:ammonium acetate; C006568:ammonium nitrate