ZrO2 nanoparticles embedded in biochar modified with layered double oxides nanosheets for phosphorus removal by capacitive deionization

Phosphorus in excessive levels can cause eutrophication and destroy the aquatic ecological balance. In this work, a novel capacitive deionization (CDI) anode material was successfully fabricated for phosphorus capture by innovatively embedding ZrO2 in layered double oxides (LDO) - modified biochar (ZrO2@LDO/BC). This approach can overcome the traditional drawbacks of the lack of active sites for phosphorus capture in biochar and the poor electrical conductivity of ZrO2 and LDO. The optimal ZrO2@LDO/BC electrode possessed a high phosphorus uptake capacity (20.36 mg P/g) and low energy consumption (0.0287 kWh/m3 (0.0406 kWh/kg)), owing to its rich mesoporous structure, appropriate conductive framework, excellent electrochemical behavior, and sufficient phosphorus trapping sites. Moreover, a few critical experimental parameters were investigated for their impact on phosphorus removal. The mechanisms revealed were mainly related to the memory effect, electrostatic attractions, and ligand exchange. This work delivered new insights into biomass waste resource utilization and phosphorus control in sewage by constructing modified bagasse-derived carbon anodes.