Effect of the addition of sulfate and phosphate on the sorption and desorption of cadmium in volcanic-ash derived soils

Inés Ahumada T.1, Mario Salazar J.1, Inés Vergara F.1 y Eduardo Schalscha B.1

The efteet of phosphate and sulfate applieation on Cd sorption and desorption was studied in two voleanic ash soils (Osorno and Vilcún). Soils were first equilibrated with Na2HPO4 or Na2SO4 solution and, then with Cd(CIO4)2 solution, maintaining the soil pH and a constant ionic stregth. To desorb cadmium, Ca(CIO4)2 and NaCIO4 solutions were used. Cadmium sorption in both soils increased with the phosphate or sulfate pre-treatments, being more pronounced in the former case. However with the highest sulfate applieation no increase in cadmium retention was found. Cadmium desorption is less pronounced in the phosphate than in the sulfate treated soils.

Keywords: cadmium, sorption desorption Cd, phosphate-Cd interaction, sulfate-Cd interaction.
1 Facultad de Ciencias Químicas y Farmacéuticas, Universidad de Chile. Casilla 233, Santiago, Chile.