MOF [NH2-MIL-101(Fe)] as a powerful and reusable Fenton-like catalyst

Abstract

Several metal-organic frameworks (MOFs) were evaluated as a Fenton-like catalyst for water treatment in a screening process. Herein, we report hydrothermally prepared NH2-MIL-101(Fe) can offer a dual function of good adsorption and excellent Fenton-like catalytic performances for organic pollutant removal. To understand the mode of action of both –NH2 and Fe, MIL-101(Fe) and NH2-MIL-101(Al) were comparatively investigated. It was found that the adsorption followed Langmuir isotherm and correlated well with pseudo-second-order kinetic model. Pseudo-first-order model was used to describe the catalysis performance. A complete decoloration of a relatively high concentration of RhB (0.25 mmol/L) by was achieved within only 4–10 min at a wide range of pH, and attained a high degradation rate constant (K) of 0.66 min−1 and 1.09 min−1at pH 7.2 and pH 11, respectively. These results were comparatively high, and tackling the problem of strict pH value (3.1) of Fenton reaction, and even of most of the Fenton-like catalysts, which are active only in acidic or near natural pH. Moreover, that outstanding performance was maintained after five successive reuse cycles. More importantly, the material potential use in the real application was validated by RhB mineralization (97.7 % TOC removal in 20 min), and by treating real textile wastewater (83 % TOC removal in 30 min). That excellent performance is a result of the synergetic effect between the high adsorption, fast electron transfer, and sustainable Fe ions release. The possible degradation mechanism was proposed.