engleski

The Effect of pH on Efficiency of Sorption/Desorption of Heavy Metals on Natural and Iron-modified Zeolite

The removability of zinc, cadmium, copper and lead ions on natural zeolite (NZ) and its iron- modified form (IMZ) through sorption and desorption in relation to the initial pH was examined in order to investigate their possible application as materials for permeable reactive barrier (PBR). The analysis of the amount of metal uptake on zeolites and the equilibrium pH of the solution indicates that the uptake of heavy metals takes place in three zones. The width of the middle optimal zone for metal uptake depends on the type of metal cation and the solubility constant. It has been found that the sorption of copper is highly sensitive to the effect of pH, especially onto IMZ. In the optimal zone, the selectivity sequence of heavy metals on IMZ has the order Pb>Zn>Cd>Cu. The study of desorption of saturated IMZ at different pH values indicates its buffering properties and the ability to retain heavy metals at pH>3.18.

Natural zeolite ; iron-modified zeolite ; heavy metals ; sorption/desorption

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