Use of natural zeolites charged with ammonium or carbon dioxide in phytoremediation of lead- and zinc-contaminated soils

BACKGROUND:Zeolites are hydrated aluminosilicate characterized by high catione exchange capacity. The application of zeolites to different technologies is feasible, particularly to remediation technologies. The present work has the purpose to test the use of natural zeolites (clinoptilolite) in phytoremediation of a lead- and zinc-contaminated soil. The soil was mixed with different doses of zeolites (uncharged), zeolites charged with ammonium and zeolites charged with carbon dioxide. The plant used for the experiment was Mirabilis jalapa L. RESULTS: The treatment with uncharged zeolites influenced positively M. jalapa growth in increasing plant biomass production of 15–20% and in reducing, at the same time, the accumulation of metals in the aerial part to a greater extent for lead (phytostabilization). The mixtures with only NH+ 4 -charged zeolites had a toxic effect on the plants, but when uncharged or CO2-charged zeolites were added to the former themetal accumulation in the aerial parts increased. CONCLUSION: The limitation of metal accumulation in the aerial part of the plant in the pots with uncharged zeolites could imply their use in phytostabilization treatments; however the application in a phytoextraction process of the mixtures with zeolites appropriately charged with ammonium, even in amixture with CO2-charged zeolites, appears more promising.