Georgian laumontite as an immobilizing agent for remediation of lead-contaminated soil

Heavy metals are a major source of environmental pollution, and the problem is becoming increasingly critical worldwide. Soil contamination by heavy metals is particularly hazardous because these elements are non-biodegradable, can accumulate in the soil for many years, and are readily taken up by plants.  One of the major factors determining the solubility of heavy metals in soil is low soil pH.   The addition of zeolite to soil significantly increases its pH, facilitates heavy metal adsorption on its surface, and ultimately reduces their solubility and bioavailability.     

The presented work investigates commercially available Georgian natural zeolite laumontite to evaluate its feasibility as an immobilizing agent for Pb⁺² ions in lead-contaminated soils. The adsorption of lead ions (pb⁺²) was studied in pure soil and in the soil amended with different proportions (10, 20, 30%) of laumontite (Lmt). The addition of zeolite increased soil pH by 4.52% (soil+10% Lmt), 9.68% (soil+20% Lmt), and 13.95% (soil+30% Lmt) compared with the untreated soil, where no zeolite was added. Correspondingly, the amount of immobilized Pb⁺² ions in the soil samples increased, with the highest retention observed in the soil sample containing 30% laumontite. The results confirm the feasibility of the application of Georgian laumontite as an immobilizing agent for the remediation of lead-contaminated soil.