In–situ growth of Ni/Ce bimetallic organic framework composites on biochar for efficient phosphate adsorption

To efficiently and economically remove phosphates from wastewater, this study employed a microwave–assisted hydrothermal method to successfully synthesise a bimetallic Ni/Ce organic framework composite supported on biochar. Compared to other adsorbents, this composite exhibits smaller particle size, more uniform morphology and greater defect density. Its unique structure facilitates electron transfer between the metals and the support while increasing the number of oxygen vacancies, thereby significantly enhancing adsorption performance. Adsorption experiments demonstrate that NiCe–BC–MOFs achieves adsorption equilibrium within 80 min, with a maximum adsorption capacity of 266.67 mg P/g – far exceeding most reported values in the literature. The material exhibits excellent adaptability and stability across a broad pH range (2 – 10), in the presence of multiple coexisting anions, and within diverse aquatic matrices. Its high efficiency was further validated in real phosphorus–containing wastewater. Its adsorption mechanism involves the synergistic action of hydrogen bonding, ligand exchange, ion exchange, and electrostatic attraction. Furthermore, the incorporation of biochar effectively reduces material costs, and after five cycles, the adsorption capacity remains above 82%, demonstrating good regenerability. Consequently, NiCe–BC–MOFs represent a phosphate adsorption material that combines high efficiency, low cost, and environmental friendliness, offering broad application prospects.