Zirconium modified biochar fiber with balanced phosphorus adsorption efficiency and recyclability: A detailed study on the mechanisms of attenuation of adsorption capacity

In the realm of phosphorus (P) adsorption, balancing adsorption capacity and recyclability is crucial. We propose a novel approach by integrating functional metal (Zr) with one-dimensional (1DL) biochar fiber to create P adsorbents. Three synthesis methods—impregnation-pyrolysis, co-precipitation, and hydrothermal synthesis—are evaluated for their effects on P adsorption performances. 1DL adsorbents prepared by impregnation-pyrolysis achieve about 100% of P removal at low concentrations (1.1–5.6 mg-P/L), outperforming 0D powdered and 3D porous granular counterparts. The usage cost of the prepared 1D adsorbent (including the preparation and regeneration costs) is 44.8% of commercial Phoslock® after 10 cycles. Noteworthy is our effort in delving into the mechanisms underpinning capacity attenuation during the regeneration of the P adsorbent—a facet scarcely explored in antecedent inquiries. Long-term applications over 60 days demonstrate the cost-effectiveness and low ion leaching toxicity of the 1DL adsorbent. This study not only advances adsorbent synthesis but also underscores 1DL adsorbents as a promising option for P removal and recovery.