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Adsorption of Free Lead (Pb 2+ ) by Pedogenic Oxides, Ferrihydrite, and Leaf Compost
Author(s) -
Sauvé Sébastien,
Mart ı ´ nez Carmen Enid,
McBride Murray,
Hendershot William
Publication year - 2000
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj2000.642595x
Subject(s) - ferrihydrite , adsorption , pedogenesis , compost , chemistry , aqueous solution , environmental chemistry , inorganic chemistry , soil water , soil science , geology , biology , ecology
Iron oxides and organic matter have a high capacity to adsorb Pb and concomitantly maintain a low free Pb 2+ activity in solution. It is, therefore, important to assess the adsorption capacity of naturally occurring materials and evaluate their potential to reduce toxicity. The free Pb 2+ activity was measured in the solution in equilibrium with ferrihydrite (a synthetic Fe oxide), two field‐collected pedogenic amorphous oxides, and leaf compost. The experiment used a factorial design varying total Pb loading and solution pH. The results show that ferrihydrite was more efficient in lowering Pb aqueous concentration than the two pedogenic oxides. Furthermore, of the two pedogenic oxides examined, a higher Pb 2+ activity was maintained in solution at equilibrium with the most crystalline phase, which also has a lower surface area relative to the other adsorbents. Leaf compost maintained a significantly higher free Pb 2+ activity, relative to the various oxides. The experimental data could be fitted to a semi‐mechanistic model predicting free Pb 2+ activity as a function of total Pb loadings and pH, with R 2 varying from 0.77 to 0.92.