The elimination of dissolved copper, zinc, cadmium and lead by coprecipitation with iron(III) hydroxide was investigated. The reaction conditions of the batch experiments were adopted from water treatment. Conditional distribution coefficients show the order Cd < Zn < Cu < Pb for increasing interaction of the metals with the ferric hydroxide. The presence of nitrilotriacetate (NTA) decreases the efficiency of the metal elimination. NTA is also able to remobilize metals from the metal enriched precipitation. There is a significant effect, even at low concentrations of a few µmol/l. Remobilization of Cu, Zn and Cd increases, remobilization of Pb decreases with reaction time. The “ageing” of the precipitation plays an important role for the yield of the reactions. From a broad application of NTA in detergents an increase of the concentration of dissolved metal species has to be expected.

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