Adsorption characteristics of white pottery clay towards Pb(II), Cu(II), and Cd(II)

The adsorption characteristics of metal ions in unitary (Pb(II), Cu(II), and Cd(II)); binary (Pb(II)-Cu(II), Pb(II)-Cd(II), and Cu(II)-Cd(II)); and ternary (Pb(II)-Cu(II)-Cd(II)) systems in white pottery clay were investigated. The influence of the white pottery clay content, pH value, and ion strength on Pb(II) adsorption was analyzed, and the kinetic and isothermal equilibrium adsorption characteristics of Pb(II), Cu(II), and Cd(II) are discussed. The results showed that the adsorption reactions of white pottery clay for Pb(II), Cu(II), and Cd(II) are all rapid reactions that reach equilibrium in 180 min. The pseudo-second-order kinetic model fits the experimental results well. The Langmuir model can accurately predict the isothermal adsorption process of Pb(II), Cu(II), and Cd(II), and the monolayer maximum adsorption capacity of white pottery clay reached 159.236, 38.491, and 26.991 mg/L, respectively. Cu(II) can significantly inhibit the adsorption of Pb(II) on white pottery clay in the Pb(II)-Cu(II) binary system, and the inhibition effect is stronger at a higher Cu(II) concentration, while Cd(II) shows less of an inhibitory effect in the Pb(II)-Cd(II) binary system. The competitive adsorption effect superimposes in the Pb(II)-Cu(II)-Cd(II) ternary system, which results in a significant decrease in the capacity of white pottery clay to adsorb all three metals. Among them, the adsorption capacity of Pb(II) decreases with increasing Cu(II) and Cd(II) concentrations, whereas the adsorption of Cu(II) and Cd(II) is less affected by concentration changes of Pb(II).