Transport of Nickel in Different Soils: Column Experiments and Kinetic Modeling

Abstract

Kinetic sorption and column miscible displacement transport experiments were performed to quantify the extent of retention and the mobility of Ni in different soils. Results from kinetic sorption indicated that sorption of Ni was time dependent and highly nonlinear, with the sorption affinity of Webster loam (a fine‐loamy, mixed, superactive, mesic Typic Endoaquoll) > Olivier loam (a fine‐silty, mixed, active, thermic Aquic Fraglossudalf) > Windsor sand (a mixed, mesic Typic Udipsamment). A multireaction and transport model (MRTM) was capable of describing the observed nonlinearity and time‐dependent adsorption of Ni for all the soils. Column transport experiments showed that Ni mobility was strongly retarded, with extensive tailing or slow release during leaching. In the Webster soil, breakthrough results revealed that Ni was highly immobile, where <20% of the applied Ni was mobile. In contrast, for the Olivier and Windsor soil columns, 50.4 and 68.3%, respectively, of the applied Ni was recovered in the effluent solution. The MRTM model that accounted for nonlinear reversible kinetics and irreversible reactions is recommended to describe Ni transport in the soils, and incorporation of reversible equilibrium reaction was not necessary. Moreover, the model adequately predicted the Ni distribution with depth in the columns subsequent to pulse application and leaching.