Molybdate Adsorption Characteristics of Volcanic‐Ash‐Derived Soils in Chile

Abstract

Soils derived from volcanic ash in Chile present a high adsorption capacity for molybdate. Competitive studies with chloride, sulfate and phosphate suggest that molybdate has a high affinity for the adsorption sites in these soils. The mechanism involved on the adsorption of molybdate is qualitatively explained by the theories developed by Hingston et al. (1968, 1972) for anion adsorption by iron and aluminum oxides.It is concluded that molybdate adsorption by volcanic‐ashderived soils is due mainly to the presence of allophane and amorphous aluminum, silicon and iron compounds and is not influenced by the organic matter content of this soil.