Effects of Artemisia ordosica roots on the cadmium adsorption characterization on particulate organic matter and soils.

Particulate organic matter (POM) is an effective adsorbent for decreasing the contaminant of cadmium, but little is known about the relevant mechanisms under the effect of plant. In this work, POM were used to study the removal of Cd in the initial concentration range of 0-4.46 mmol L at pH 5.5, and the effect of Artemisia ordosica roots and pH on kinetics and equilibrium of cadmium adsorption on POM and soils were examined. The result indicated that adsorption kinetics fit well with the pseudo-second-order kinetic model, and the equilibrium data for Cd adsorption fit much well to the Langmuir model. The maximum adsorption capacity for POM at equilibrium corresponding to the monolayer coverage reached 0.287 mmol/g for Cd. The amount of Cd adsorbed in the POM and soil increased with the increase of pH from 4 to 8.5. The Artemisia ordosica roots decreased Cd adsorption in POM; instead, the adsorption capacity of soil for Cd was improved under the effect of Artemisia ordosica roots. The Fourier Transform Infrared spectroscopic (FTIR) analysis indicated that the complexation of POM and Cd was mainly through sulfhydryl, hydroxyl and carboxyl groups.