Lead sorption–desorption from organic residues

• Published in: Environmental technology 2011-01, Vol.32 (4), p.353-361
• Main Authors: Duarte Zaragoza, Victor M, Carrillo, Rogelio, Gutierrez Castorena, Carmen M
• Format: Article
• Language: English
• Subjects: acid soils; Adsorption; Agriculture, rearing and food industries wastes; alkaline soils; Applied sciences; bioavailability; Biological and medical sciences; Biomass; biosorption; Biotechnology; cation exchange capacity; cattle manure; Chemical engineering; chemical equilibrium; coffee beans; coffee pulp; Composting; coprecipitation; Desorption; environmental technology; Exact sciences and technology; Fundamental and applied biological sciences. Psychology; heavy metals; hulls; Hydrogen-Ion Concentration; Kinetics; lead; Lead (metal); Lead - chemistry; Manure; Manures; Mathematical analysis; Methods. Procedures. Technologies; Mexico; Organic materials; organic matter; Others; oxides; polluted soils; Pollution; precipitation; remediation; Residues; Soil - chemistry; Soil Pollutants - chemistry; Soils; Sorption; sorption isotherms; Various methods and equipments; vermicomposts; Wastes
• ISSN: 1479-487X; 0959-3330; 1479-487X
• DOI: 10.1080/09593330.2010.491133

Sorption and desorption are mechanisms involved in the reduction of metal mobility and bioavailability in organic materials. Metal release from substrates is controlled by desorption. The capacity of coffee husk and pulp residues, vermicompost and cow manure to adsorb Pb²⁺ was evaluated. The mechanisms involved in the sorption process were also studied. Organic materials retained high concentrations of lead (up to 36,000 mg L⁻¹); however, the mechanisms of sorption varied according to the characteristics of each material: degree of decomposition, pH, cation exchange capacity and percentage of organic matter. Vermicompost and manure removed 98% of the Pb from solution. Lead precipitated in manure and vermicompost, forming lead oxide (PbO) and lead ferrite (PbFe₄O₇). Adsorption isotherms did not fit to the typical Freundlich and Langmuir equations. Not only specific and non‐specific adsorption was observed, but also precipitation and coprecipitation. Lead desorption from vermicompost and cow manure was less than 2%. For remediation of Pb‐polluted sites, the application of vermicompost and manure is recommended in places with alkaline soils because Pb precipitation can be induced, whereas coffee pulp residue is recommended for acidic soils where Pb is adsorbed.