To enhance the phosphate removal performance, a porous material (La MOF-20 %-C) was prepared by selectively removing the thermally unstable NH 2 -BDC ligand from a lanthanum dual organic ligand MOF through pyrolysis. This innovative approach equips La-MOF-20 %-C with dual functionalities: high phosphate adsorption capacity and robust antibacterial effects. The adsorbent showcased a remarkable phosphate adsorption capacity of 97.24 mg P/g and reached equilibrium within 90 min. The material exhibits good anti-interference capability, and the presence of multiple coexisting ions does not affect its adsorption performance. Additionally, it can be used over a wide pH range (3.0–8.0) and has good reusability. Mechanistic studies indicated that electrostatic attraction and ligand exchange were the primary mechanisms for phosphate adsorption. Moreover, La MOF-20 %-C effectively inhibited the metabolic activities of Escherichia coli and Staphylococcus aureus through phosphorus starvation and electrostatic attraction, demonstrating significant antibacterial properties. Importantly, the fabrication of this material into a filter membrane enabled the successful treatment of 16.8 L of actual wastewater, achieving an overall phosphate removal rate of over 85 %, and effectively removing total bacteria. These findings highlight La MOF-20 %-C as a highly promising material with dual functionality for phosphate removal and bacterial inhibition.
The metal or metal clusters and organic ligands are relevant to the selectivity and performance of phosphate removal in MOFs, and the electron structure, chemical characteristics, and preparation method also affect efficiency and commercial promotion. However, few reports focus on the above, especially for 2D MOF nanomaterials. In this work, two 2D Ln-TDA (Ln = La, Ce) nanosheets assembled via microwave- and ultrasonic-assisted methods are employed as adsorbents for phosphate (H2PO4−, HPO42−) removal for the first time. Their microstructure and performance were characterized using XRD, TEM, SEM, AFM, FTIR, zeta potential, and DFT calculations. The prepared 2D Ln-TDA (Ln = La, Ce) nanosheets exposed more adsorption sites and effectively reduced the restrictions of mass transfer. Based on this, the Langmuir model was employed to estimate the maximum adsorption capacities of the two kinds of nanosheets, which reached 253.5 mg g−1 and 259.5 mg g−1, which are 553 times and 3054 times larger than those for bulk Ln-TDA (Ln = La, Ce), respectively. Additionally, the kinetic data showed that the adsorption equilibrium time is fast, approximately 15 min by the pseudo-second-order model. In addition, the prepared products not only have a wide application range (pH = 3–9) but also offer eco-safety in terms of residuals (no Ln leak out). Based on the XPS spectra, FTIR spectra and DFT calculations, the main adsorption mechanisms included ligand exchange and electrostatic interactions. This new insight provides a novel strategy to prepare 2D MOF adsorbents, achieving a more eco-friendly method (microwave- and ultrasonic-assisted synthesis) for preparing 2D Ln-based MOF nanosheets by coordinative unsaturation to boost phosphate adsorption.
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