Synthesis Of Composite Metal Heterogeneous Fenton Catalysts And Their Catalytic Activity

Refractory organic wastewater treatment has been a problem. Fenton oxidation process can degrade many refractory organic compounds with high removal efficiency. In recent years the development of heterogeneous catalysts in Fenton oxidation process becomes a research hotspot. In this paper, the heterogeneous composite metal catalysts were prepared using mesoporous zeolites as catalyst support, and their catalytic activities were studied.The difference of the characterization between catalyst adding trace metal and the CuO-M41-O550is small.The well dispered metal catalysts had large surface area, a lot of small pore within it. Adding another metals improved the dispersion of the main catalyst. The zeolite kept its mesoporous structure and ordered channels. Nanoparticles were formed in the ordered channels. After the reduction of the catalysts at controlled temperature for a short time, the copper appears in the form of multiple valences.At neutral conditions, pCBA degradation rate over Fe, Ce supported catalysts were very low, while the Cu supported catalysts showed good catalytic performance.5wt.%was appropriate loading of Cu metal. Comparing with copper acetate, copper nitrate was a better precursor for the catalyst.Adding metal Ce, Fe reduced the activity of Cu supported catalyst. Adding Co promoted invalid hydrogen peroxide decomposition. After reduction, the activity of Cu supported catalyst significantly increased. Adding the appropriate amount of metal Mn can promote the degradation.· OH probe experiments showed that the addition of Mn and the hydrogen reduction treatment significantly increased the steady-state concentration of· OH, while adding metal Ce reduceed the steady-state concentration of· OH. Among all the composite metal catalysts Cu(0)-Mn(0)-MCM41-O550-H170had the highest activity.,In the neutral conditions,the pCBA degradation rate reaches up to82%after1hour reaction, while that over the catalyst CuO-MCM41-O550was only37%, and the steady-state concentration of [· OH]ss reduced to a quarter of that in the former case. DMPO-EPR spectroscopy further confirmed that the reaction produced·OH, which was an importantactive species. Catalytic degradation activity under acidic conditions was almost the same from that under neutral conditions.It was found that the hydrogen reduction and the addition of metal Mn enhanced the ability of the catalyst to give electrons. Electron transfer on the surface of the catalysts accelarated the dechlorination of chlorinated organic compounds,the product were further oxidized. However, this mechanism can not apply to phenol degredation.