Constructing N Defects Mediated MIL-53@MIL-101 Heterophased Junctions for Boosting Robust TC Adsorption in Wastewater

Iron-based metal–organic frameworks (MOFs), exemplified by MIL-53(Fe) and MIL-101(Fe), embody the immense potential for proficient pollutant remediation owing to their elevated porosity and excellent photocatalytic performance. In this study, MIL-53(Fe) materials with varying crystal structures were synthesized by judicious modulation of precursor concentrations. Morphological and structural characterizations of Fe-MOFs executed through SEM and XRD, revealed that the structure transformed from MIL-53(Fe) to MIL-101(Fe) as the Fe3+ (or H2BDC) concentration decreased from 15 to 1 mmol to form a heterophased composite of MIL-53@MIL-101 at a Fe3+ concentration of 5 mmol. The prepared MIL-53@MIL-101 exhibited the largest porous size of 12.6 nm and a BET surface area of 68.2 m2/g. Within this intricate framework, the optimized Fe-MOFs of MIL-53@MIL-101 demonstrated an adsorption prowess of unparalleled finesse, achieving an efficiency ratio of 95.49% and an equilibrium adsorption capacity of 92.58 mg/g, underlined by a kinetic grace reflected in a rate constant of 0.253 min–1. Thermodynamic investigations suggested that the ΔH0 and ΔS0 values for the adsorption process were 4.25 kJ/mol and 122.24 J·mol–1·K–1, respectively. Furthermore, the adsorption kinetics analysis showed that both the pseudo-first-order model and the pseudo-second-order model fit the experimental data well, with an activation energy (Ea) of 12.30 kJ/mol, consistent with the characteristics of physical adsorption. These revelations delineate a path toward the ecofriendly design of efficacious Fe-based absorbents, poised to orchestrate the purification of water with environmental sagacity.