Schwertmannites are characterized by low crystallinity and high specific surface area,which significantly impact the interface process of antimony(Sb)in the environment.In this study,three types of Schwertmannites,namely H-SCH(synthesized by H2O2 oxidation method),M-SCH(synthesized by KMnO4 oxidation method),and Y-SCH(H-SCH modified by ethanol),were prepared.The study investigated the kinetics mechanisms of Sb(Ⅲ)adsorption by the three synthesized Schwertmannites through comprehensive monitoring and characterization.The results revealed that H-SCH combined more Fe during the synthesis process,resulting in a more stable framework structure.M-SCH and Y-SCH exhibited higher structural SO42-compared to H-SCH.Particularly,Y-SCH displayed a larger specific surface area and abundant surface-active hydroxyl groups.Both M-SCH and Y-SCH presented decreased trends in mineral crystallinity compared to H-SCH.The adsorption kinetics indicated that the adsorption of Sb(Ⅲ)by the three Schwertmannites followed the models of pseudo-second-order kinetics and particle diffusion,suggesting dominant chemical adsorption and a non-homogeneous diffusion process.XRD analysis revealed relative stability in Y-SCH during the adsorption process of Sb(Ⅲ),with no observed mineral phase transformation.However,the H-SCH and M-SCH groups exhibited characteristic peaks of ferrihydrite during the late stage of adsorption process,enhancing the adsorption of Sb(Ⅲ)due to the high adsorption abilities of ferrihydrite to Sb(Ⅲ).Chelation of surface hydroxyl functional groups was the main mechanism for Sb(Ⅲ)adsorption by the three synthesized Schwertmannites.During the adsorption process,Sb(Ⅲ)was oxidized to Sb(V)by Fe(Ⅲ),and the formed Sb(OH)6-further exchanged with exchangeable SO42-on the surface of Schwertmannites,inherently enhancing the adsorption of Sb(Ⅲ)by Schwertmannites.This work provides a theoretical basis and a comprehensive dataset for the practical application of Schwertmannites in the treatment of wastewater containing Sb.
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