Content of selected heavy metals in ni-contaminated soil following the application of halloysite and zeolite

Abstract

Nickel has been listed as a priory control pollutant by the United States Environmental Protection Agency (US EPA). Compared with other methods, the combination of vegetation and the addition of mineral sorbents to heavy metal-contaminated soils can be readily applied on a large scale because of the simplicity of technology and low cost. Halloysite and zeolite, among others, can be used for this purpose. A greenhouse study was performed to evaluate the feasibility of using natural zeolite, as well as raw and modified halloysite for the remediation of simulated Ni-contaminated soil. The soil was spiked with five doses of nickel, i.e. 0 (control), 80, 160, 240 and 320 mg·Ni kg-1.soil. The average accumulation of heavy metals in nickel-contaminated soil was found to follow the decreasing order of Ni>Zn>Cr>Cu>Pb. The highest reduction of Pb content was observed in soil samples taken from pots containing 80 and 160 mg·kg-1 of Ni along with the addition of modified halloysite. The strongest effects were caused by natural zeolite, which significantly reduced the average content of chromium. Contamination at 320 mg Ni·kg-1 of soil led to the highest increases in the Ni, Pb and Cr contents of soil.