Stabilization of nickel in a contaminated calcareous soil amended with low-cost amendments

Abstract

A laboratory study was planned to delineate the benefits of some low-cost soil amendments on Nickel (Ni) stabilization in a Ni-spiked soil. Six different kinds of amendments were evaluated by desorption kinetic test and sequential extraction procedure to determine their ability to reduce mobility of Ni in a Ni-spiked soil. The Ni-spiked soil was separately incubated with coal fly ash (CFA), rice husk biochars prepared at 300 °C (B300) and 600 °C (B600), municipal solid waste compost (MSWC), zero valent iron (Fe0) and zero valent manganese (Mn0) at 2 and 5% (W/W) for 45 and 90 days at 25 °C. The kinetic data obtained from 0.01 M EDTA was used to simulate desorption equations. The Sequential extraction method was also used as a suitable method for identification of chemical forms of Ni and its mobility. According to the results, application of amendments reduced exchangeable and carbonate forms of Nirate with respect to control treatment. Changes in chemical forms of Ni and their conversion into less soluble forms in treated soils was observed with incubation time. Application of Mn0, Fe0, CFA, and B300 to soil samples significantly decreased Ni desorption rate compared to the control treatment. The lowest Ni release was achieved by Mn0-treatment at 5%. Biphasic pattern of Ni desorption kinetic was fitted well by the model of two first-order reactions. From the practical point of view, Fe0, Mn0, CFA, and B300 treatments are effective in Ni stabilization, while using Mn0 and Fe0 at 5% can be recommended for immobilization of Ni from calcareous polluted soil.