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

An effective Fenton-like FeO/MIL-88A/BC catalyst was fabricated by combining magnetite nanoparticles (FeO) with diamond-shaped MIL-88A and -derived biochar for the degradation of 2-NP. The elemental composition, morphology, functional groups, surface net charge, and crystallographic phase of the FeO/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 HO/FeO/MIL-88A/BC. Laboratory experiments showed that the 2-NP degradation efficiency by HO/FeO/MIL-88A/BC reached 91.04% within 120 min at pH = 5, FeO/MIL-88A/BC = 10 mg, and HO concentration = 500 mg L. Kinetic studies indicated that the Fenton-like degradation of 2-NP followed a second-order model, while HO decomposition was best described by a first-order model. Quenching tests indicated that the Fenton-like reaction of 2-NP proceeded 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 FeO/MIL-88A/BC catalysts. The intermediates obtained from the Fenton-like degradation of 2-NP by the FeO/MIL-88A/BC catalyst were predicted from the GC-MS spectrum.