Synthesis Of Nanocomposite For Catalytic Ozonation

Phenolic compounds are one of the refractory organic pollutants in wastewater. Theiracute toxicity presents a great threat to the health of humans and ecosystems. Hence, thesolution to phenolic compounds removal is urgent. Owing to the strong oxidizing andenvironmentally friendly nature of ozone in water, the eco-friendly, efficient, and segregativecatalyst used in catalytic ozonation organic pollutants has become a research hotspot.In this research, Cu-Co, Cu-Ag, and Fe-Ni nanocomposite catalysts were synthesized.Different approaches such as AAS, XRD, TEM （SEM）, and BET were used to characterizethe nanocomposite catalysts. Accordingly, the phase composition, morphology characteristicand specific surface area were obtained. Comparing with the ozonation alone, the degradationefficiency of phenol was promoted in the ozonation process with the three kinds ofnanocomposite catalysts. And the Cu-Co, Cu-Ag, and Fe-Ni nanocomposite catalysts wereeffective in catalytic ozonation phenol in a wide initial pH range （4-8）. In addition, thestability of Cu-Ag, and Fe-Ni nanocomposite catalysts were higher than that of Cu-Conanocomposite catalyst. And the Cu-Ag, and Fe-Ni nanocomposite catalysts were easy toseparate from the water compared with the Cu-Co nanocomposite catalyst. The relationshipamong the adsorption of phenol, the catalytic activity, and the interaction between ozone andthe composite catalyst was studied in this paper. A preliminary suggestion of the active centreand the mechanism in the catalytic ozonation of phenol was proposed.For the system of Cu-Co nanocomposite catalyst, CuO, Co₃O₄, and Cu-Co-Onanocatalysts were synthetized with co-precipitation method. Comparing with the ozonationalone, the degradation efficiency increased28.86%and103.44%for O₃/Co₃O₄andO₃/Cu-Co-O, respectively. However, there was no catalytic activity for CuO. We proposedthat a synergistic effect of copper and cobalt existed on the catalytic ozonation of phenol andaqueous ozone depletion, which showed higher activity than either copper or cobalt oxidealone. Moreover, the trivalent cohbalt in the Cu-Co-O composite was proposed as the validstate.For the system of Cu-Ag nanocomposite catalyst, Cu-N, Cu-HCHO, Cu-Ag, andCu-Ag-HCHO nanocatalysts were prepared by changing the raw materials. Comparing withthe ozonation alone, the degradation efficiency increased39.09%,28.18%,24.21%, and54.93%for O₃/Cu-N, O₃/Cu-HCHO, O₃/Cu-Ag, and O₃/Cu-Ag-HCHO, respectively. Weproposed the synergistic effect of Cu₂O, Cu, and Ag increased the catalytic activity of ozonedepletion. In addition, the copper oxide and silver oxide would be produced after theinteraction between ozone and Cu-Ag-HCHO. And the copper oxide and silver oxide mightoxidate the reducing by-products during ozonation of phenol. Moreover, the introduction of silver increased the fastness of the catalyst, which contributed to the catalytic activity ofphenol degradation.For the system of Fe-Ni magnetic nanocomposite catalyst, the magnetic Ni-Fe_xO_yandFe_xO_ynanocatalysts were obtained. The characterization results showed Fe_21.34O₃₂andmagnetic Fe₃O₄both existed in Ni-Fe_xO_yand Fe_xO_ynanocatalysts. And magnetic Ni was alsoobserved in Ni-Fe_xO_ynanocatalysts. Comparing to the ozonation alone, the degradationefficiency increased12.56%and42.84%for O₃/Fe_xO_yand O₃/Ni-Fe_xO_y. We proposed theintroduction of nickel promoted the interaction between ozone and Ni-Fe_xO_y, and thenboosted the degradation efficiency of phenol. In addition, the magnetism of Ni-Fe_xO_ywas anadvantage when the catalyst was separaed from water. The Ni-Fe_xO_ymight be prospective incatalytic ozonation of organic pollutants.