Assessing the influence of natural zeolite on toxic heavy metals immobilization and their transfer into Zea mays L.

ABSTRACT. This research presents the efficiency of surfactant-modified (SMNZ) and unmodified natural-zeolite (UNZ) in the immobilization of Cr3+, Pb2+, and Cd2+ in the soil system. Phillipsite is identified as a major component of the host zeolite. Soil mixed with 20% UNZ retained the highest amount of all metals on the top layer of the soil-zeolite column. The lowest transfer of metals into the maize crop was observed at 30 mg of UNZ/kg soil. The experimental conditions such as pH, dose, stirring speed, contact time, and initial metal ions concentration showed significant effect on adsorption of Cr3+, Pb2+, and Cd2+ onto both unmodified and modified zeolite (phillipsite). The maximum adsorption (mg/kg) onto control soil, soil mixed with SMNZ and UNZ was 67.1, 90.9, 151.5 for Cr3+, 84.8, 120.5, 238.1 for Pb2+, 83.3, 116.3 and 212.8 for Cd2+ respectively. Thus, the use of natural zeolite, particularly UNZ has an important role in controlling the mobility of Cr3+, Pb2+, and Cd2+ metal ions in the soil system and thus their transfer to plant system. KEY WORDS: Zeolite, Immobilization, Heavy metals, Column, Pot trial, Batch Bull. Chem. Soc. Ethiop. 2023, 37(6), 1351-1368. DOI: https://dx.doi.org/10.4314/bcse.v37i6.5