Design of a magnetic Fenton-like catalyst by decorating diamond-shaped MIL-88A with Chenopodium-derived biochar for nitrophenol degradation: optimization and mechanistic insights

An effective Fenton-like Fe 3 O 4 /MIL-88A/BC catalyst was fabricated by combining magnetite nanoparticles (Fe 3 O 4 ) with diamond-shaped MIL-88A and Chenopodium -derived biochar for the degradation of 2-NP. The elemental composition, morphology, functional groups, surface net charge, and crystallographic phase of the Fe 3 O 4 /MIL-88A/BC catalyst were examined using various characterization techniques, including XPS, SEM, FTIR, ZP, and XRD. Optimization experiments were conducted to determine the optimal Fenton-like degradation conditions for 2-NP using H 2 O 2 /Fe 3 O 4 /MIL-88A/BC. Laboratory experiments showed that the 2-NP degradation efficiency by H 2 O 2 /Fe 3 O 4 /MIL-88A/BC reached 91.04% within 120 min at pH = 5, Fe 3 O 4 /MIL-88A/BC = 10 mg, and H 2 O 2 concentration = 500 mg L −1 . Kinetic studies indicated that the Fenton-like degradation of 2-NP followed a second-order model, while H 2 O 2 decomposition was best described by a first-order model. Quenching tests indicated that the Fenton-like reaction of 2-NP proceeded via a radical mechanism and confirmed that the ˙OH radicals are the controlling reactive O-species. The degradation mechanism of 2-NP was proposed based on the XPS spectra of the neat and used Fe 3 O 4 /MIL-88A/BC catalysts. The intermediates obtained from the Fenton-like degradation of 2-NP by the Fe 3 O 4 /MIL-88A/BC catalyst were predicted from the GC-MS spectrum. A magnetic Fe 3 O 4 /MIL-88A/BC composite was fabricated from BC, MIL-88A and magnetite for the catalytic degradation of 2-nitrophenol via a Fenton-like reaction.