Adsorption characteristics of Zn(II) and Pb(II) by river sediments under hydrodynamic conditions

Abstract

This study aims to investigate the process and mechanism of adsorption of Zn(II) and Pb(II) by river sediments under hydrodynamic conditions and provide a basis for preventing and controlling heavy metals in rivers. For this purpose, surface sediments were collected from the Ganjiang River in Nanchang, Jiangxi Province, China, and the adsorption kinetics, isotherms, and the effect of different initial pH on the adsorption process of heavy metals Zn(II) and Pb(II) under different hydrodynamic conditions were simulated using the particle entrainment simulator (PES) resuspension simulation device. The results showed that under different hydrodynamic conditions, the adsorption equilibrium of Zn(II) and Pb(II) can be reached within 6 h, and the adsorption amount of Pb(II) by the sediment was significantly higher than that of Zn(II). Pseudo-second-order dynamics and the Elovich model can better describe the kinetics of adsorption in both metals (R2 > 0.90). Langmuir and Freundlich's models could better simulate the adsorption isotherms of Zn(II) and Pb(II) on sediments. According to the results of △G and –F, the adsorption of Zn(II) and Pb(II) is mainly physical adsorption. Furthermore, there are certain differences in the adsorption of heavy metals Zn(II) and Pb(II) by sediments at different pH values.