Herein, La(OH)3 decorated magnetic porous biochar (MPBC) was synthesized via KHCO3 activation and hydrothermal processes. The La-to-MPBC mass ratio of 3:1 described as La3-MPBC possessed a monolayer phosphate adsorption capacity of 116.08 mg/g across a pH range of 3.0-6.0 with fast attainment of adsorption equilibrium in 150 min. Moreover, the phosphate adsorption was substantially stable during the interference of various co-existing ions with over 92% of phosphate removal and 77% of desorption efficiency maintained after four recycles. And La3-MPBC was easily separated by magnet force with negligible La and Fe leakages within the pH range of 3.0-10.0. Furthermore, La3-MPBC was supported to achieve phosphate binding through the synergistic actions of electrostatic attraction, ligand exchange, inner-sphere complexation and weak precipitation. Significantly, La3-MPBC exhibited a high performance for decontaminating low-concentration phosphate to meet regulatory requirements. All these results suggested La3-MPBC to be an ideal candidate for phosphate removal in real applications.
Keywords: Adsorption; Biochar; Lanthanum; Magnetic nanoparticles; Phosphate.
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