Efficient phosphate removal and flocculation of Microcystis aeruginosa via a flower-like spherical Metal-Organic Framework La-BDC-NH2: Investigation of performance and mechanism

Eutrophication of aquatic water bodies and the consequent harmful algal blooms (HABs) induced by excessive phosphorus (P) have become a critical global environmental challenge. In this study, a flower-like spherical metal-organic framework (MOF) material, La-BDC-NH 2 , was successfully synthesized via a hydrothermal method for the simultaneous phosphate adsorption and Microcystis aeruginosa flocculation. Its physicochemical properties were systematically characterized using a suite of analytical techniques, including X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM). The results of phosphate adsorption performance tests demonstrated that the maximum adsorption capacity of this material for phosphate reached 75.65 mg/g at 25 °C. In the microalgal flocculation experiments, the harvesting efficiency of Microcystis aeruginosa exceeded 95% at the optimal dosage of 0.2 g/L. Notably, La-BDC-NH 2 retained excellent phosphate adsorption and microalgal flocculation performance over a broad pH range (4–10) and initial algal concentration range (OD 680  = 0.1–1.0), thus exhibiting robust adaptability to complex aquatic environments. Furthermore, this material could efficiently convert proteinaceous extracellular organic matter (EOM) released by Microcystis aeruginosa into more stable humic acid-like substances, thereby mitigating the environmental risks associated with EOM accumulation. Ultimately, this study demonstrates that La-BDC-NH 2 is a multifunctional, highly efficient, and stable environmental functional material for aquatic eutrophication control. It has good application prospects in controlling HABs and aquatic eutrophication, and provides a practical and feasible technical strategy for mitigating harmful algal blooms in eutrophic aquatic systems.