Competitive adsorption of thallium in different soils as influenced by selected counter heavy metals

This study was conducted to investigate thallium (Tl) adsorption in different soils, including acidic Jeonju (JJ), neutral Iksan (IS), and alkaline Danyang (DY) soils treated with various single counter metal ions and to examine the competitive adsorption of Tl with other metals, including cadmium (Cd), copper (Cu), nickel (Ni), lead (Pb), and zinc (Zn), in multicomponent systems. Thallium buffering capacity of the soils was ordered as IS > DY > JJ soil in the single-component systems, whereas it was DY > IS > JJ soil in the multicomponent systems. In the competitive systems of Tl with different single counter metals, the Tl adsorption capacity of the soils ranged from 20.33 to 88.38 and Tl bonding energy values ranged from 0.369 to 0.731. Thallium adsorption capacity and bonding energy were negatively correlated. Selectivity sequences of metals in multicomponent systems were Pb > Tl > Cu > Ni > Zn > Cd in the JJ soil, Pb > Cu > Tl > Zn > Cd > Ni in the IS soil, and Pb > Cu > Tl ≥ Zn > Cd > Ni in the DY soil. The metal buffering capacity in the JJ, IS, and DY soils varied from 293.2 to 1125.2. The values were ordered as Tl ≫ Pb ≥ Zn ≥ Ni > Cu ≥ Cd in the JJ soil, Pb > Cu > Tl ≫ Ni > Zn ≥ Cd in the IS soil, and Pb > Cu ≫ Tl > Ni > Cd ≥ Zn in the DY soil.