Preparation And Performance Of Magnetic Nano-catalysts For The Activation Of Peroxymonosulfate On The Degradation Of Organic Pollutants

For treating organic pollutants from wastewater,Acid Orange II?AO II?and 2,4-Dichlorophenol?2,4-DCP?,as two kind of tyical dyes and phenolic compounds were chosen as the target pollutant in this paper.Fe₃O₄@C/MnCo₂O₄ and Fe₃O₄@C/C₃N₄ were explored for their effect in peroxymonosulfate?PMS?activation for oxidative degradation of AOII and 2,4-DCP.Two nanoparticals were characterized by FT-IR,XRD,XPS,TEM,SEM,EDS and VSM.It is show that MnCo₂O₄ and g-C₃N₄ were loaded on the surface of Fe₃O₄@C and two kinds of magnetic nano-composites were synthesized successfully.The effect of several paramenters,including the influence on different factors of degradation of AO II and 2,4-DCP,degradation mechanism,degradation thermodynamic and kinetic model,reusability and regeneration of catalyst were intestigated.Main conclusions are listed as following:?1?The study of decolorization of AO II with ‘Fe₃O₄@C/MnCo₂O₄ + PMS' system indicates that the dye solution could be nearly completely decolorized in about 25 min over a wide pH range?pH 4.1-8.1?,and 98 % removal could be achieved in 15 min without pH adjustment?pH=6.38?.The increasings of catalyst dosage,PMS concentration and reaction temperature also promote the AO II decolorization efficiency with ‘Fe₃O₄@C/MnCo₂O₄ + PMS' system.The increasing of PMS concentration also improve the removal of TOC in AO II solution,95 % TOC of the solution was removed in 6 h when PMS concentration was 1.2 g L-1,indicateing the system can not only result in the decolorization but also degradation of wase water completely.Sulfate radical(SO₄^-·)with strong oxidizing ability activated from PMS by Fe₃O₄@C/MnCo₂O₄ were proposed to be the dominant active species during the oxidation process of AO II.The catalyst was magnetically separable and displays good stability and reusability after use for six cycles.?2?The study of degradation of 2,4-DCP with ‘Fe₃O₄@C/MnCo₂O₄ + PMS' system indicates that 2,4-DCP could be nearly completely removed in 30 min over a wide pH range?pH 6.05-8.02?,and optimum efficiency with nearly completely removal of 2,4-DCP in 15 min was achieved at the pH was 8.02.The increasings of catalyst dosage,PMS concentration and reaction temperature also promote the 2,4-DCP degradation efficiency with ‘Fe₃O₄@C/MnCo₂O₄ + PMS' system.The degradation mechanism implying that SO₄^-· activated from PMS by Fe₃O₄@C/MnCo₂O₄ were proposed to be the dominant active species during the oxidation process of 2,4-DCP.Chlorine ion was detected and TOC of the 2,4-DCP solution was decreased during the degradation process.90 % TOC of the solution was removed in 6 h when PMS concentration was 3.6 g L-1.Meanwhile,Mass spectra was used for degradation byproduct detection.?3?The study of decolorization of AO II with ‘Fe₃O₄@C/C₃N₄ + PMS' system indicates that preparation condition such as mass ratio in composite,calcination temperature,calcination time was found.96 % decolorization could be achieved in 20 min with PMS and Fe₃O₄@C/C₃N₄ prepare by optimum method.The increasings of catalyst dosage,PMS concentration,reaction temperature and suitable pH condition also promote the AO II decolorization efficiency with ‘Fe₃O₄@C/C₃N₄ + PMS' system.68.24 % of the TOC of the solution was removed in 8 h when PMS concentration was 0.6 g L-1.The decolorization curves fitted well with the first-order kinetics.SO₄^-· and OH· were proposed to be the dominant active species during the oxidation process.?4?The study of degradation of 2,4-DCP with ‘Fe₃O₄@C/C₃N₄ + PMS + Vis' system indicates that 2,4-DCP could be removed well in 40 min over a pH range?pH 2.08-7.02?,hight removal rate was achieved in 30 min over a pH range?pH 3.56-5.00?.The increasings of catalyst dosage,PMS concentration and reaction temperature also promote the 2,4-DCP degradation efficiency with ‘Fe₃O₄@C/C₃N₄ + PMS + Vis' system.75.26 % of the TOC of the solution was removed in 2 h when PMS concentration was 1.2 g L-1.TOC,concentration of chlorine ion and mass spectrum have proven that the system could effectively degradate 2,4-DCP into small intermediate products.SO₄^-·,O2^-· and h⁺ were proposed to be the dominant active species during the oxidation process by mechanism experiment.