Selektivní adsorpce kationtu kovu v přítomnosti fosfátového aniontu na oxyhumilitu a hydratovaných oxidových soustavách

Abstract

The aim of this work was to find optimum conditions for two-stage selective adsorption of ions heavy metal (Cu(II) or Cd(II)) from aqueous solutions at phosphates presence. In the first stage oxyhumolite was used as selective Cu(II) or Cd(II) sorbent, in the second stage blast furnace slag and its modified form was used for the retention of phosphates. It was shown that selectivity of oxyhumolite depends on the value of equilibrium pH and adsorption time. The adsorption of ions heavy metal (Cu(II) or Cd(II)) and phosphates on oxyhumolite are two mutually independent processes taking place at different rates, which enables their simple separation. The high adsorption efficiency (E) of oxyhumolite for ions heavy metal (up to E = 95 % at pH 3.7) is cause by the presence of humic acids. It was proved that the presence of oxyhumolite in the first stage positively influences the adsorption efficiency of the materials used in the second stage of the adsorption process. Soluble humic compounds and residues of humic acids support the precipitation of Ca-phosphates on blast furnace slag and the ions exchange reactions on its modified form. Species binding of phosphates ions to the surface of the adsorbent influences their desorption subsequent. The desorption efficiency of both slags for phosphates was about 60 %.