Orange G degradation by heterogeneous peroxymonosulfate activation based on magnetic MnFe_(2)O_(4)/α-MnO_(2) hybrid

Wastewater containing an azo dye Orange G(OG)causes massive environmental pollution,thus it is critical to develop a highly effective,environmental-friendly,and reusable catalyst in peroxymonosulfate(PMS)activation for OG degradation.In this work,we successfully applied a magnetic MnFe_(2)O_(4)/α-MnO_(2) hybrid fabricated by a simple hydrothermal method for OG removal in water.The characteristics of the hybrid were investigated by Xray diffraction,scanning electron microscopy,energy-dispersive X-ray spectroscopy,Fourier transform infrared spectroscopy,Brunauer–Emmett–Teller method,vibrating sample magnetometry,electron paramagnetic resonance,thermogravimetric analysis,and X-ray photoelectron spectroscopy.The effects of operational parameters(i.e.,catalytic system,catalytic dose,solution pH,and temperature)were investigated.The results exhibited that 96.8% of OG degradation was obtained with MnFe_(2)O_(4)/α-MnO2(1:9)/PMS system in 30 min regardless of solution pH changes.Furthermore,the possible reaction mechanism of the coupling system was proposed,and the degradation intermediates of OG were identified by mass spectroscopy.The radical quenching experiments and EPR tests demonstrated that SO_(4)•̶,O_(2)•̶,and 1O2 were the primary reactive oxygen species responsible for the OG degradation.The hybrid also displayed unusual stability with less than 30%loss in the OG removal after four sequential cycles.Overall,magnetic MnFe2O4/α-MnO2 hybrid could be used as a high potential activator of PMS to remove orange G and maybe other dyes from wastewater.

Hierarchical porous induced competent removal of low concentration azo dye molecules by generating a leachy crystalline structure H-MIL-53(Fe)

The development in technology of synthetic azo dyes,has led to excessive water resources pollution.Eve n at lower concentration they can impart the quality of water and human life.Herein,we have developed a novel synthesis strategy via introducing salicylic acid(SA)for the synthesis of a leachy crystalline material H-MIL-53(Fe)with hierarchical pores(HP)and exposed coordination unsaturated sites(CUS),which had higher surface area and larger pore volume than the as synthesized MIL-53(Fe).Due to these characteristics,H-MIL-53(Fe)was competent removal of orange G(OG,one of the frequently used azo dyes)with equilibrium in 300 min and the maximum adsorption capacity of 163.9 mg/g.The adsorption mechanism of OG onto H-MIL-53(Fe)was mostly based on electrostatic attraction between CUS of HMIL-53(Fe)along with HP as active species to OG diffusion and bind.By comparing H-MIL-53(Fe)with other adsorbents for OG adsorption,it is undoubtedly that H-MIL-53(Fe)can be used as a promising adsorbent for OG removal from aqueous solutions.