Fe-based metal-organic frameworks as Fenton-like catalysts for highly efficient degradation of tetracycline hydrochloride over a wide pH range: Acceleration of Fe(II)/ Fe(III) cycle under visible light irradiation

Insights into the novel application of Fe-MOFs in ultrasound-assisted heterogeneous Fenton system: Efficiency, kinetics and mechanism

“…S4 ). This result is consistent with that in Fe-MOF/vis/H 2 O 2 and Fe-MOF/H 2 O 2 systems, in which the combination with coordinative unsaturated iron sites is the only reaction sites [10] , [34] . However, in this system, part of H 2 O 2 could be decomposed to ·OH by US directly, and cavitation effect could also contribute to degradation.…”

“…The higher reaction rate in acidic solution are attributed to the fact that H 2 O 2 is easy to be decomposed to molecular oxygen and H 2 O in alkaline solution [41] . It is worth noting that the degradation efficiency of TC-HCl is still considerable even under the condition of pH = 11, and the kinetic constant is greater than the highest kinetic constant of other literatures [10] , [34] . This advantage is due to the involvement of US.…”

“…Sonoluminescence is light emission due to chemiluminescence from reactive species produced during the collapse of cavitation bubbles, it has a wide range of wavelengths including ultraviolet and visible light, which could stimulate either ultraviolet or visible light-induced semiconductors to behave as photocatalysts to produce electron-hole (e - -h + ) pairs [18] , [47] , [48] , [49] . According to the already reported literatures, MIL-88B is visible light responsive due to the existence of extensive oxo-iron (Fe–O) clusters [34] , [50] , [51] , [52] , which makes it reasonable to be stimulated by sonoluminescence. Electrons in the conduction band could react with oxygen to generate • O 2 – (Eqs.…”

“…They are all higher than that of α-Fe 2 O 3 (0.056 min −1 ). Generally, the unsaturated coordination sites of metals are responsible for the catalytic performance [22] , [34] . To further explore the reason that MIL-88B exhibited better US/Fenton performance than other two MOFs, cyclic voltammetry (CV) and CO adsorption infrared analysis (CO-FTIR) were carried out.…”

Heterogeneous Fenton catalysts: A review of recent advances

“…Fe-oxo clusters were regarded as the absorption antennae, and Fe-MOFs showed substantial absorption in the visible region. Among the MIL-101, MIL-53 and MIL-88B, photo-Fenton activity was highest in the MIL-101, because of its higher number of coordinatively unsaturated iron sites ( Wu et al, 2020 ). Generally, the metal centres in a MOF are fully occupied by the organic ligands, and this inhibits the metal sites from activating H 2 O 2 .…”