posted on 2024-01-30, 10:44authored byBoxi Li, Xufeng Zhang, Jing Shen, Aihua Zhang, He Huang
Bimetallic metal–organic frameworks (BMOFs) have
garnered
significant attention in the field of environmental remediation due
to their more diverse adsorption sites compared to monometallic metal–organic
frameworks (MOFs). Different energy barriers must be overcome for
different metal ions and organic linkers to form MOFs. However, the
impact of the synthesis temperature on the crystallization and porosity
structure of BMOFs has been rarely studied. In this work, PCN-333
series-based BMOFs with different Fe/Al ratios were prepared by a
solvothermal method at temperatures of both 135 and 150 °C. The
synthesis temperature and Fe/Al ratio have significant effects on
the crystal structure and specific surface area of bimetallic PCN-333,
leading to the different adsorption performance of the PCN-333 for
Congo red (CR). The Fe/Al-PCN-333–135(3:1) and Fe-PCN-333–150
exhibited the maximum CR adsorption capacities of 3233 and 3933 mg/g,
respectively, surpassing the capacities of most previously documented
adsorbents. The Langmuir model and pseudo-second-order kinetics can
well describe the adsorption process of CR on Fe/Al-PCN-333–135(3:1)
and Fe-PCN-333–150. Combining the isotherm adsorption behavior
with the thermodynamic parameters, CR adsorption on BMOFs is a single-layer
endothermic chemical adsorption. Furthermore, Fe/Al-PCN-333–135(3:1)
and Fe-PCN-333–150 exhibited regenerability and reusability
for three cycles with reasonable efficiency. This work is of great
significance in the field of engineering BMOF materials to treat dye
wastewater.