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

Abstract

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 minutes. 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 (SO4•−) and non-radical routes (1O2), of which 1O2 was dominant. Furthermore, even after a continuous 400-minute 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.