Phosphate adsorption performance and mechanisms by nanoporous biochar–iron oxides from aqueous solutions
2020
Zhang, Zhaoran | Yu, Haiqin | Zhu, Rixin | Zhang, Xue | Yan, Liangguo
To evaluate the adsorption mechanism and performance of phosphate onto the composite of low-cost biochar and iron oxide, four biochar–iron oxides, namely biochar–magnetite (BC-M), biochar–ferrihydrite (BC-F), biochar–goethite (BC-G), and biochar–hematite (BC-H), were prepared by fabricating iron oxide to porous biochar. The biochar–iron oxides had huge surface areas of 691–864 m²/g and average pore diameters of 3.4–4.0 nm. Based on the characterization analysis of FTIR, XRD, XPS, and zeta potential, the interactions of electrostatic attraction, ligand exchange, and deposition dominated the phosphate adsorption onto biochar–iron oxides. The maximum adsorption capacity of phosphate followed the order of BC-G > BC-F > BC-H > BC-M. The isotherm data of BC-M and BC-H were well fitted by the Langmuir and Freundlich models, while those of BC-G and BC-F followed the Langmuir model. In addition, BC-M, BC-F, BC-G, and BC-H owned excellent regeneration ability and adsorption performance in practical (simulated) wastewater environment. Then the biochar–iron oxides exerted extensive and satisfactory prospect in wastewater remediation and recycling application in soil.
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