Nitrogen-doped lignin-derived biochar with enriched loading of CeO 2 nanoparticles for highly efficient and rapid phosphate capture.

Development of lignin-derived carbon adsorbents with ultrahigh phosphate adsorption activity and rapid adsorption kinetics is of great importance, yet limited success has been achieved. Herein, we develop a CeO ₂ functionalized N-doped lignin-derived biochar (Ce@NLC) via a cooperative modification strategy for effective and fast phosphate capture. The novel modification strategy not only contributes greatly to the loading of well-dispersed CeO ₂ nanoparticles with a smaller size, but also significantly increases the relative concentration of Ce(III) species on Ce@NLC. Consequently, an enhanced capture capacity for phosphate (196.85 mg g ^-1 ) as well as extremely rapid adsorption kinetics were achieved in a wide operating pH range (2-10). Interestingly, Ce@NLC exhibited a strong phosphate adsorption activity at even low-concentration phosphorus-containing water. The removal efficiency and final P concentration reached 99.87% and 2.59 μg P L ^-1 within 1 min at the phosphate concentration of 2 mg P L ^-1 . Experiments and characterization indicated that Ce(III) species plays a predominant role for the phosphate capture, and ligand exchange, together with electrostatic attraction, are the main adsorption mechanism. This work develops not only an efficient carbon-based adsorbent for phosphate capture, but also promotes the high-value application of industrial lignin.
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