Peroxymonosulfate activation by Mn_3O_4/metal-organic framework for degradation of refractory aqueous organic pollutant rhodamine B

An environmentally friendly Mn‐oxide‐supported metal‐organic framework(MOF),Mn3O4/ZIF‐8,was successfully prepared using a facile solvothermal method,with a formation mechanism proposed.The composite was characterized using X‐ray diffraction,scanning electron microscopy,transmission electron microscopy,X‐ray photoelectron microscopy,and Fourier‐transform infrared spectroscopy.After characterization,the MOF was used to activate peroxymonosulfate(PMS)for degradation of the refractory pollutant rhodamine B(RhB)in water.The composite prepared at a0.5:1mass ratio of Mn3O4to ZIF‐8possessed the highest catalytic activity with negligible Mn leaching.The maximum RhB degradation of approximately98%was achieved at0.4g/L0.5‐Mn/ZIF‐120,0.3g/L PMS,and10mg/L initial RhB concentration at a reaction temperature of23°C.The RhB degradation followed first‐order kinetics and was accelerated with increased0.5‐Mn/ZIF‐120and PMS dosages,decreased initial RhB concentration,and increased reaction temperature.Moreover,quenching tests indicated that?OH was the predominant radical involved in the RhB degradation;the?OH mainly originated from SO4??and,hence,PMS.Mn3O4/ZIF‐8also displayed good reusability for RhB degradation in the presence of PMS over five runs,with a RhB degradation efficiency of more than96%and Mn leaching of less than5%for each run.Based on these findings,a RhB degradation mechanism was proposed.

Recent advances and trends of heterogeneous electro-Fenton process for wastewater treatment-review

Electrochemical advanced oxidation processes (EAOPs) are effective and environmentally friendly for the treatment of refractory organic pollutants.Among EAOPs,heterogeneous electro-Fenton (EF) process with in-situ formation of hydrogen peroxide (H_(2)O_(2)) is an eco-friendly,cost-effective and easy-operable technology to generate hydroxyl radicals (;OH) with high redox potential.The generation of;OH is determined by the synergistic H_(2)O_(2)formation and activation.The surface catalytic mechanisms for H_(2)O_(2)activation in the heterogeneous EF process were discussed.Some required features such as heteroatom doping and oxygen groups for H_(2)O_(2)formation via selective two-electron oxygen reduction reaction (ORR) with carbonaceous electrode are summarized.The solid Fenton catalysts and integrated functional cathodes that widely used in heterogeneous EF for wastewater treatment are grouped into few classes.And the brief discussion on catalytic activity and stability of materials over different experimental conditions are given.In addition,the application of heterogeneous EF process on the remediation of emerging contaminants is provided.The challenges and future prospects of the heterogeneous EF processes about catalytic fall-off and multi-step/complex techniques for water purification are emphasized.