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| Adsorption kinetics and environmental impact mechanisms of schwertmannite on phosphorus |
| Received:July 25, 2024 |
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| KeyWord:schwertmannite;phosphorus;dynamic representation;adsorption mechanism;influencing factor |
| Author Name | Affiliation | E-mail | | Dudagula | Inner Mongolia Ecological Environment Inspection Technical Support Center, Hohhot 010011, China | | | SONG Wenjie | Pioneer College, Inner Mongolia University, Hohhot 010000, China | | | XIE Zhilei | Inner Mongolia Environmental Monitoring Station, Hohhot 010011, China | | | LI Hao | School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China | | | LI Zhichao | School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China | | | HE Jiang | School of Ecology and Environment, Inner Mongolia University, Hohhot 010021, China | ndjhe@imu.edu.cn |
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| Abstract: |
| To explore the adsorption mechanism of schwertmannite（SCH）for PO43- and the possibility of its application as a PO43- adsorbent, this study focuses on the adsorption behavior of SCH towards PO43-, employing continuous characterization of SCH throughout the process as a means to investigate its adsorption kinetics for PO43-. The study also discusses the impact of pH and the competitive adsorption of As（Ⅲ） and Cr（Ⅵ）ions on SCH′s ability to adsorb PO43-, thereby revealing the underlying mechanism governing SCH′s affinity for PO43-. The findings indicate that the adsorption of PO43- by SCH follows quasi-second-order kinetics and a three-stage intraparticle diffusion model, with chemical adsorption being the primary mechanism within a non-homogeneous diffusion process. The equilibrium adsorption capacity within 24 hours can reach 17.38 mg·g-1. We observed that PO43- can interact with SCH through ligand exchange and ion exchange processes. Specifically, OH groups on the surface of SCH are preferentially involved in ligand exchange with PO43-, followed by ion exchange with SO42- within SCH, both mechanisms contributing to enhanced stability. Continuous characterization results further revealed the generation of secondary minerals such as water iron during the process of PO43- adsorption by SCH. Furthermore, we found that As（Ⅲ）competes for adsorption sites with PO43-, thus inhibiting its uptake by SCH; conversely, Cr（Ⅵ）promotes the adsorption of PO43- by providing additional binding sites, and alkaline conditions were shown to be more conducive to effective PO43- adsorbing performance by SCH. |
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