اثر کاربرد سطوح مختلف کود گاوی و بیوچار حاصل از آن بر سینتیک جذب نیکل در یک خاک آهکی

Biochar is a soil amendment that has a high capacity to adsorb heavy metals. The aim of this study was to identify the influence of cow manure and its biochar on nickel adsorption and to determine the best models to describe the kinetics of Ni retention. Accordingly, cow manure and its biochar were added to the soils at the levels of 0, 2 and 4%, and samples were incubated for 90 days. Soil samples were equilibrated with 100 mg L-1 Ni solutions for periods of 1 to 2880 min. Then, the concentration of nickel was measured. The Ni adsorption data were fitted to seven commonly used kinetic models. The results showed that cow manure and its biochar application in all times and levels increased nickel adsorption more than the control. There was also a significant difference (P<0.05) between cow manure and its biochar. Application of 4% biochar, as compared with the same level of cow manure, and the control, increased the Ni adsorption by 23 and 44%, respectively. Power function was the best fitted model describing the patterns of Ni adsorption, as evidenced by the relatively high values of R2 and the low values of SE. However, the Elovich function had some R2 similar to that of power function, but it could not be used as an adequate function to investigate the kinetics of nickel adsorption due to their high values of SE. The zero order, the first order, the second order, the third order, and parabolic diffusion equations were not well fitted to the Ni adsorption data.