Phytoremediation of metal: Lithium

Abstract

Phytoremediation is a cost-effective and applicable new technology that uses plants to achieve remediation of various contaminants from agricultural areas and healthy agricultural production. Rare earth elements have gained a commercial meaning with developing technology and new technological areas, mainly solar cells. However, contamination of TCEs in the environment is continuously increasing as risk analyses have shown that they can have harmful biological effect on living organisms. In this work, the usability of phytoremediation technology in lithium metal removal was investigated. The accumulation of lithium metal in the plant (Cress (Lepidium sativum L.)) has been shown with the comparison of different lithium doses. The experiment was conducted according to the randomized complete blocks design with three replicates. The lithium doses used in the trials were 0.5, 1, 2, 4, and 8 mg kg-1. At the end of 45 days of vegetative growth period of the plants in the pots, they were harvested and sequential analyses were conducted. Later, Li metal contents in the dried plant samples were determined using inductively coupled plasma optical emission spectrometry (ICP-OES). The soil used in the experiment were sieved with 2 mm mesh and submitted to analyses for pH (1/2.5 soil/water mixture according to Jackson’s method), CaCO3 (Scheibler calcimeter), electrical conductivity (EC, 1/2.5 soil/water), organic matter content (Walkey-Black method). The texture of the soil was determined according to Bouyoucos Hydrometer method. According to the results, lithium was accumulated in the plant especially at higher concentrations. There was not a significant difference between 0.5 and 1 mg kg-1 doses. The effect of increasing concentrations of lithium was found to be significant at 1% at the doses studied. As the negative effects of Li toxicity on plants are not clear yet due to the limited information on the motility of Li from the soil to the plants, the results of this study are expected to increase the experimental findings in this field. However, the economical aspect of phytoremediation compared to other remediation techniques seems to be a green solution to effectively remove lithium from soil. © 2022 Elsevier Inc. All rights reserved.