Sorption and Desorption of Vanadate, Arsenate and Chromate by Two Volcanic Soils of Equatorial Africa

Sorption of oxyanions by soils and mineral surfaces is interest due to their role as nutrients or pollutants. Volcanic are variable charge soils, rich in active forms aluminum iron, capable sorbing anions. desorption vanadate, arsenate, chromate two African andosols was studied laboratory experiments. isotherms were determined equilibrating at 293 K soil samples with oxyanion solutions concentrations between 0 100 mg L−1 V, As, Cr, equivalent 0−2.0 mmol V L−1, 0−1.3 As 0−1.9 Cr NaNO3; ICP-mass spectrometry the equilibrium solution. After sorption, equilibrated 0.02 M NaNO3 study desorption. The adjusted mathematical models. NaNO3, experiments carried out a 1 mM phosphate. sorption vanadate arsenate greater than 90% amount added, while much lower (19–97%). Silandic Andosol attributed non-crystalline Fe Al, Vitric Andosol, crystalline iron species play relevant role. fitted Freundlich model, conformed Temkin model. For highest solution, sorbed 37–38 kg−1, 25 7.2–8.8 kg−1. low for high Cr. comparison reveals pronounced hysteresis both Andosol. Phosphate induced almost no desorption, moderate considerable