Adsorption performance and mechanism for Pb(Ⅱ), Cu(Ⅱ) and Zn(Ⅱ) removal from aqueous solutions by Fe-CSH derived from steel slag

Steel slag was used as an in-situ source and sodium silicate as an activator to synthesize iron-hydrated calcium silicate (Fe-CSH) with hierarchical porous structure, which was used as an adsorbent for the efficient removal of heavy metals such as Pb(Ⅱ), Cu(Ⅱ) and Zn(Ⅱ) from the aqueous solutions. The effects of initial solution pH, Fe-CSH dosage and initial solution concentration on the adsorption performance of Pb(Ⅱ), Cu(Ⅱ) and Zn(Ⅱ), and the adsorption mechanism were revealed by means of adsorption kinetics, thermodynamics and characterization means such as X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Search Engine Marketing (SEM), Transmission Electron Microscope (TEM), Brunauer Emmet Teller (BET) and X-ray Photoelectron Spectroscopy (XPS). The results showed that the adsorption processes of Fe-CSH on Pb(Ⅱ), Cu(Ⅱ) and Zn(Ⅱ) were all in accordance with the proposed secondary kinetic model, and the adsorption on Pb(Ⅱ) and Cu(Ⅱ) were in accordance with the Langmuir model, while the adsorption on Zn(Ⅱ) was more in accordance with the Freundlich model, and the adsorption capacities were 1546mg/g, 483mg/g and 369mg/g, respectively. The efficient removal of heavy metals Pb(Ⅱ), Cu(Ⅱ) and Zn(Ⅱ) by Fe-CSH can be achieved through the mechanisms of physical adsorption, ion exchange, precipitation, and ligand complexation. This study followed the environmental protection concept of waste for waste, which was of great significance for the resourceful use of adsorbents synthesized from solid wastes and the treatment of wastewater purification. © 2024 Chemical Industry Press Co., Ltd.. All rights reserved.