Mining and metallurgic processes are the most crucial causes of heavy metal pollution in the Chinese soils. The contaminated soils and sediments in Chenzhou, Hunan province in the South of China. Contamination of many different heavy metals is reported. Antimony (Sb) are present in various polluted sites. A better process description of the sorption processes of antimony in contaminated soils and sediments is needed. Therefore, an optimization of existing analysis techniques are recommended for the determination of the free antimony present in the samples.
In this study, the ability to use the Donnan Membrane Technique for oxy-anions speciation was tested, more in particular for free antimony. The method was studied with artificial antimony solutions at different background concentrations, with different antimony species and with various antimony concentrations. It was concluded that high concentrations of antimony and background electrolyte concentrations tend to block the migration of antimony through the anion exchange membrane. Since the equilibria were not reached, the time needed for equilibrium was calculated using the obtained data and varied from 13 days to 126 days. The longest equilibrium times, e.g. 126 days, were attributed to the slow migration of the neutral species Sb(OH)3. Field DMT experiments for anions were performed in different rivers in Chenzhou, in Hunan Province. A high percentage of free antimony was present in the river systems and the attachment of Sb to dissolved organic carbon was suggested.
The desorption behaviour was determined by batch sorption tests for the total amount of antimony and for the two species Sb(III) and Sb(V), using the HPLC-ICP-MS. The behaviour was tested under different pH values and varying CaCl2 concentrations. As a conclusion, high distribution constants Kdes seem to be attributed to the strong adsorption on the soils and irreversible sorption behaviour of Sb. A clear effect of iron oxides and the initial Sb concentration present in the soil is observed. A change in pH and desorption solution concentration (CaCl2) show a rather variable impact on the desorption behaviour. Often, it has been assumed that antimony (Sb) and arsenic (As) have the same behaviour in the environment.