Stabilization Pb, Zn, and Cd-contaminated soil by means of natural zeolite

This article aims to investigate the stabilization of Pb, Zn, and Cd contai ned in contaminated soil from a former mining site in Montevecchio, Sardini a, using clinoptilolite-rich tuff from Pentalofos, Evros. The study include d (I) batch experiments and their environmental characterization and (2) co lumn experiments. The first tests involved 1-month pot experiments with var ying soil-zeolite mixtures, and their evaluation was carried out by standar d USEPA leaching tests (TCLP, EPT test, SPLP), Moderate solubility reductio ns were recorded according to the TCLP (Pb: 38%, Zn: 33%, and Cd: 32% due t o the introduction of competing Na ions in the solution, while the EPT test showed more significant variations (Pb: 55%, Zn: 74%, and Cd: 46%). A majo r decrease is achieved in both cases by 10% w/w zeolite addition. The study was complemented by column experiments involving soil-zeolite mixtures elu ted by CH3COOH solutions (0.003N and 0.05N). The solubility of Pb was reduc ed by 50 to 60% compared with the control column, thus indicating the consi derable selectivity of clinoptilolite for Pb. In addition, Na and Ca measur ements in the leachates confirmed that the immobilization of Pb was mainly attributed to ion exchange reactions.