Effects of pH, organic acids, and inorganic ions on lead desorption from soils

• Published in: Environmental pollution (1987) 2006-09, Vol.143 (1), p.9-15
• Main Authors: Yang, J.Y., Yang, X.E., He, Z.L., Li, T.Q., Shentu, J.L., Stoffella, P.J.
• Format: Article
• Language: English
• Subjects: Acetic Acid - pharmacology; Adsorption; Adsorption–desorption; Applied sciences; Biodegradation, Environmental; Biological and physicochemical properties of pollutants. Interaction in the soil; Chelating Agents - pharmacology; Citric Acid - pharmacology; Copper - chemistry; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; Environmental Pollution; Environmental Restoration and Remediation - methods; Exact sciences and technology; Humic Substances; Hydrogen-Ion Concentration; Ions; Lead; Lead - chemistry; Lead - toxicity; Malates - pharmacology; Organic acid; Oxalic Acid - pharmacology; Pollution; Pollution, environment geology; Soil and sediments pollution; Soil Pollutants - chemistry; Soil Pollutants - toxicity; Variable charge soil; Zinc - chemistry
• ISSN: 0269-7491; 1873-6424
• DOI: 10.1016/j.envpol.2005.11.010

The desorption characteristics of lead in two variable charge soils (one developed from Arenaceous rock (RAR) and the other derived from Quaternary red earths (REQ)) were studied, and the effects of pH value, organic acid, and competitive ions were examined. Desorption of Pb 2+ decreased from nearly 100.0 to 20.0% within pH 1.0–4.0 in both soils, and then the decrease diminished at pH > 4.0. Organic ligands at relatively low concentrations (≤10 −3 mol L −1) slightly inhibited Pb 2+ desorption, but enhanced Pb 2+ desorption at higher concentrations. In this study, citric acid or acetic acid at higher concentrations (>10 −3 mol L −1) had the greatest improvement of Pb 2+ desorption, followed by malic acid; and the smallest was oxalic acid. Desorption of the adsorbed Pb 2+ increased greatly with increasing concentrations of added Cu 2+ or Zn 2+. Applied Cu 2+ increased Pb 2+ desorption more than Zn 2+ at the same loading. The adsorption–desorption process is a basic and important reaction in soils controlling Pb 2+ mobility and bioavailability.