| TiO2 has attracted much attention due to its excellent photocatalytic properties,easy availability,long-term stability and non-toxicity.However,TiO2 has the disadvantages of narrow excitation zone and low solar energy utilization.The morphological regulation of TiO2 and the doping modification of heterogeneous materials are the main ways to increase visible light photocatalysis,improve photocatalytic performance,and expand the application of TiO2.Therefore,in this thesis,the semiconductor material graphene is doped into TiO2,and the visible light photocatalytic performance of TiO2 is enhanced by the optimization of preparation conditions and the adjustment of graphene doping mode,and the degradation of organic dyes and antibiotics is realized.The immobilized carbonic anhydrase is completed by a large specific surface area and a rich surface-active group.Based on the synergistic photocatalytic technique of nano-TiO2 and lamellar graphene oxide and the magnetic separation technology of Fe304,the outsourced of graphene-doped TiO2 magnetic nanocomposites was synthesized by gel-sol method and one-step alkali alcohol method.The structure is a monolithic graphene semi-coated with a nanoflower-like TiO2 magnetic sphere.The specific surface area of the outer cladding material is 283.780 m2·g-1,and the nano-flower structure of the TiO2 layer and the sheet graphene structure increase the photocatalytic area and improve the adsorption performance of the pollutants.At the same time,the doping of graphene also increases the performance of visible light photocatalysis.Under visible light,the 5h degradation rates of organic dyes Rhodamine 6G and methyl orange were 97.6%and 99.4%,respectively.The 6h degradation rate of chloramphenicol was 80.1%.The study used an outsourced material to immobilize carbonic anhydrase.During the immobilization process,it was found that the addition of a small amount of zinc sulfate solution can significantly increase the immobilization rate and relative enzyme activity of the immobilized enzyme.By adjusting the carrier content,immobilization time and temperature,the zinc sulfate concentration was determined to be 5 mmol/L,the carrier amount was 2 mg,the solid loading time was 1 h,and the solid storage temperature was 25?,which was the best immobilization of carbonic anhydrase condition.The solid loading rate is above 91%,and the relative enzyme activity is above 96%.The temperature tolerance,pH tolerance and storage stability of immobilized carbonic anhydrase were significantly better than free enzymes.After the immobilized enzyme was used for 6 times,the relative enzyme activity still reached the level of 82%.Enzyme kinetic experiments showed that the affinity of the carbonic anhydrase after immobilization with the substrate decreased,but the structure of the enzyme was not destroyed and the enzyme activity was not reduced.In order to maximize the proportion of graphene doped into TiO2 and enhance the photocatalytic performance of visible light,the experiment was carried out by adjusting the order of addition of lamellar graphene,combined with gel-sol method and one-step alkali alcohol method to obtain intrinsic graphene-doped TiO2 magnetic nanocomposites.The structure is a nano-flower-like TiO2 layer completely encapsulating the sheet graphene and Fe3O4 on the graphene.Under visible light,the intrinsic material can completely degrade chloramphenicol and tetracycline,and the degradation rate at 5h is 89.7%and 90.8%,respectively.The results of active free radical detection showed that during the degradation of organic pollutants,O2-and h+dominated,and-OH had a smaller effect.The degradation of tetracycline by the preparation material mainly through the reaction of breaking double bond,dehydroxylation,deamination,demethylation,epoxidation and ring opening.Eventually,CO2,H2O and amino species are formed. |
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