The Studies On Preparation And Catalytic Ozonation Properties Of Graphene Supported Metal Oxide

As an important aspect of advanced oxidation technology, ozonation technology has awide application in water treatment, especially for heterogeneous catalytic ozonationtechnology, which has received intensive research because of its high efficiency in oxidizinghigh stability and refractory organic pollutants. Phenolic wastewater, mainly from gas,petrochemical and pharmaceutical industries, is a common industrial organic pollutants. It hasa wide variety of sources, with huge amount and has been listed as refractory organicpollutants by US EPA because of its high toxicity and carcinogenicity. Graphene （GN）, whichhas unique electrical, mechanical and thermal properties, is mainly used as adsorbentmaterials in water treatment. It is rarely found combined with ozone, but due to its excellentperformance, it may has a great potential in catalytic ozonation.In this study, graphite oxide （GO） were synthesized by a modified Hummers method.Then GO was used as the precursor to synthesize graphene supported nickel oxide（NiO@GN）, graphene supported titanium dioxide （TiO₂@GN） and graphene supportedcopper oxide through a chemical reduction process by using NaBH4as the reducing agent.After that, the materials were characteriazed by XRD, RS, TEM and XPS, respectively.Finallythe materials prepared were used as catalysts in catalytic ozonation of phenol.XRD, RS, TEM and XPS characterization results of NiO@GN show that NiO has beensuccessfully supported onto graphene, but the amount is small and NiO is in amorphousforms. In NiO@GN/O₃catalytic ozonation system, The presence of NiO@GN can greatlyimprove the removal rate of phenol, GN and NiO@GN have a certain amount of adsorptioncapacity towards phenol, but not in a dominant role. The removal rate of phenol has a positiveeffet with the increase of catalyst dosage and pH. However, with the increase of ozone dosage,the phenol removal rate hardly changes. The addition of t-BuOH increases the stability ofozone,especially those adsorbe onto the catalyst surface, so that the phenol removal increasesslightly, which indicates that catalytic ozonation of phenol by NiO@GN is not followed ahydroxyl radical mechanism. Through the adsorption of ozone onto the catalyst surfaceexperiment, we propose the mechanism could be as follows: ozone and phenol are bothadsorped onto catalyst surface and form a solid-liquid interface, on which ozone and phenol took reaction and phenol is degraded.XRD, RS and TEM characterization results of TiO₂@GN show that anatase spread onthe GN surface evenly. TiO₂@GN significantly improves the phenol removal rate in catalyticozonation process. The increase of catalyst dosage and pH have a positive effect on theremoval of phenol. With the increase of the initial concentration of phenol, phenol removalrate decreases, but the removal amount increases. Different dosage of T-BuOH has no effecton the phenol removal, indicating that OH is not involved in the process.XRD, RS and TEM characterization results of CuO@GN show that Cu exists on thesurface of GN in the form of a mixture of Cu₂O and CuO, and appears a certainagglomeration. CuO@GN plays a negative effect on the removal of phenol during thecatalytic ozonation process.