Influence of Dissolved Organic Carbon on the Adsorption and Desorption of Cadmium in Reclaimed Soil

Abstract

Organic acids are widespread in the environment and play an important role in the adsorption, desorption, and migration of soil cadmium (Cd). Under the effect of humic acid (HA) and citric acid, the properties and mechanism of Cd adsorption and desorption in reclaimed soil from the Panyi Mine in the Huainan mining area were investigated (CA). The addition of HA and CA inhibited the adsorption and enhanced the desorption of Cd in reclaimed soil, with HA having a stronger effect than CA. As the concentration of added HA or CA increased, the adsorption capacity of Cd in the reclaimed soil gradually decreased, while the desorption capacity gradually increased. That is, the adsorption inhibition/desorption promotion effect was stronger for higher concentrations of organic acid. Cd adsorption and desorption could be described as a logarithmic function of organic acid concentration. The kinetic curves of Cd adsorption and desorption in reclaimed soil under the influence of organic acids show that both adsorption and desorption involved two stages: a fast reaction stage followed by a slow reaction stage.

Keywords

• cadmium, citric acid, dissolved organic carbon humic acid, reclaimed soil