Evaluation of Animal Bone and Its Bone Char Application Effects on Desorption Kinetics and Chemical forms of Nickel in a Saline Calcareous Soil

In the present study, the efficiency of animal bone (RB) and its bone char (BC) (from the pyrolysis process at 500 °C) application effects on nickel (Ni) behavior was evaluated in a Ni-spiked calcareous soil. For this purpose, RB and BC at 1.5 and 3% (w/w) were added separately to Ni-spiked soil (350 mg kg-1) and after incubation process (3 months) under field capacity moisture, soil Ni behavior were investigated through desorption kinetics and sequential extraction techniques, in the laboratory of environment department, graduate university of advanced technology, Kerman (1399). Based on the results, BC due to the very high specific surface area (95.9 m2 g-1), the process of nickel exchange with calcium in its surface, and the formation of orthophosphate-Ni surface complex caused a significant reduction of Ni desorption compared to the control soil sample (without treatment). The mechanism of hydrogen ion release in RB-treated soil increased the Ni desorption compared to the control sample. The results of chemical forms of Ni in soils treated with BC and RB, showed a significant decrease (43.23-23.22%) and increase (15-97-9.9%) in Ni mobility factor, respectively, compared to the control sample (38.8%). The Two first-order reactions model, considering the biphasic process of Ni desorption in all soil samples, showed a good prediction (R2>99%) of Ni desorption kinetics. In general, the results of this study showed that the pyrolysis process, by changing the physical and chemical structure of RB, has improved the stabilizing properties of CB and finally stabilized soil Ni, which requires more attention to the application and increase of efficiency (physical and chemical modifications) of this stabilizer in future research.