Study of Trace Amounts of Lead Adsorption in the Environmental Conditions over the Layered Polyhydroxide Consisted of Iron and Magnesium

摘要

The local structure of trace amounts of lead in an adsorbent matrix that contains a high concentration of iron and magnesium (Mg_6Fe_2 (OH)_(16) (CO_3) centre dot 3H_2O) was successfully monitored by means of X-ray absorption fine structure spectroscopy combined with fluorescence spectrometry. A eutectic mixture of PbCO_3 and Pb (OH)_2 coagulated when Pb~(2+) was adsorbed from a 1.0 ppm aqueous solution, and in contrast, the major species was ion-exchanged Pb~(2+) in the case of adsorption from a 100 ppb aqueous solution. The difference was ascribed to the balance between the precipitation equilibrium for coagulation and the rate of the ion exchange reaction with surface hydroxyl groups.