Three-dimensional porous bimetallic metal–organic framework/gelatin aerogels: A readily recyclable peroxymonosulfate activator for efficient and continuous organic dye removal

As promising catalysts for the degradation of organic pollutants, metal–organic frameworks (MOFs) often face limitations due to the particle agglomeration and challenging recovery in liquid-catalysis application, stemming from their powdery nature. Engineering macroscopic structures from pulverous MOF is thus of great importance for broadening their practical applications. In this study, three-dimensional porous MOF aerogel catalysts were successfully fabricated for degrading organic dyes by activating peroxymonosulfate (PMS). MOF/gelatin aerogel (MOF/GA) catalysts were prepared by directly integrating bimetallic FeCo-BDC with gelatin solutions, followed by freeze-drying and low-temperature calcination. The FeCo-BDC-0.15/GA/PMS system exhibited remarkable performance in degrading various organic dyes, eliminating 99.2% of rhodamine B within a mere 5 min. Compared to the GA/PMS system, there was over a 300-fold increase in the reaction rate constant. Remarkably, high removal efficiency was maintained across varying conditions, including different solution pH, co-existing inorganic anions, and natural water matrices. Radical trapping experiments and electron paramagnetic resonance analysis revealed that the degradation involved radical (${\text{SO}}_4^{-}·$) and non-radical routes (¹O₂), of which ¹O₂ was dominant. Furthermore, even after a continuous 400-min reaction in a fixed-bed reactor at a liquid hourly space velocity of 27 h⁻¹, the FeCo-BDC/GA composite sustained a degradation efficiency exceeding 98.7%. This work presents highly active MOF-gelatin aerogels for dye degradation and expands the potential for their large-scale, continuous treatment application in organic dye wastewater management.