Composites Based on Natural Zeolites and Green Materials for the Immobilization of Toxic Elements in Contaminated Soils: A Review

Soil contamination by toxic elements is a global problem, and the remediation of contaminated soils requires complex and time-consuming technology. Conventional methods of soil remediation are often inapplicable, so an intensive search is underway for innovative and environmentally friendly ways to clean up ecosystems. The use of amendments that stabilize the toxic elements in soil by reducing their mobility and bioavailability is one of the simplest and most cost-effective ways to remediate soil. This paper provides a summary of studies related to the use of composites based on natural zeolites and green materials for the immobilization of toxic elements in contaminated soils and highlights positive examples of returning land to agricultural use. The published literature on natural zeolites and their composites has shown that combinations of zeolite with biochar, chitosan and other clay minerals have beneficial synergistic effects on toxic element immobilization and soil quality. The effects of zeolite properties, different combinations, application rates, or incubation periods on toxic elements immobilization were tested in laboratory scale or field experiments, whereas the mobility of toxic elements in soil was evaluated by chemical extractions of toxic elements transferred to the plants. This review highlights the excellent potential of natural zeolites to be used as single or combined sustainable green materials to solve environmental pollution problems related to the presence of toxic elements.