Sorptive and desorptive response of divalent heavy metal ions from EICP-treated plastic fines
- Vol.53(2), Apr
- USA Springer 2023
- 315-333p.
In this study, enzyme-induced calcite precipitation (EICP)-based treatment for tropical soils contaminated with divalent heavy metals such as cadmium (Cd), nickel (Ni), and lead (Pb) were evaluated for their sorption and desorption capabilities. Heavy metals were taken in three different combinations: a single metal and a combination of two and three metals. They were mixed with locally available kaolinite and montmorillonite soils. EICP-treated soil retained the maximum quantity of Cd among all the heavy metals studied. The Cd retention exceeded Ni and Pb retention. The same was confirmed with desorption studies, relying on aggressive chelants such as ethylene diamine tetra acetic acid (EDTA) and citric acid. Before subjecting the kaolinitic soil to EICP treatment, it was found that the sorption capacity for Cd and Ni was 2.124 and 1.974 mg/g for Cd and Ni, respectively. The sorptive values increased to 3.457 and 4.418 mg/g for Cd and Ni, respectively, after EICP treatment. The retention is attributed to the formation of CdCO3 and NiCO3 in the soil matrix, which exhibits very low values of solubility product even in the presence of aggressive chelants. The study establishes that EICP treatment is a prospective method for remediation of soils laced with heavy metal ions.