| With the rapid development of the medical industry,aquaculture and animal husbandry,water pollution from antibiotic abuse has been widely appreciated.Due to the wide use of antibiotics,their residual substances can be detected in the water environment.Generally,wastewater treatment plants increase the dosage to remove antibiotics,but it increases costs and produces disinfection by-products.Photocatalytic oxidation technology has become popular because of its deep treatment,wide applicability,effective use of sunlight and no secondary pollution.At present,this technology is still in the development stage and there is no mature and perfect process.Therefore,when using this technology to treat tetracycline wastewater,the following points need to be improved:（1）Zn Fe2O4with a narrow band gap（1.9 e V）is introduced to solve the problem that Ti O2can only be excited by UV light.（2）Adopt photocatalytic coupling piezoelectric effect,using external force to prompt the internal formation of dynamic piezoelectric field,to solve the problem of low catalytic efficiency of single semiconductor photogenerated carriers such as fast compound speed and slow transfer rate.（3）Since the powder particles are easily lost with water and will pollute the environment,the magnetic material is selected for modification and effective recovery using an applied magnetic field.In this study,a new and environmentally composite material was prepared by forming Type p-n heterojunction by Zn Fe2O4and Ti O2,compounded with Ba Ti O3piezoelectric material to build a photocatalytic-piezoelectric coupling system,then degraded tetracycline organic pollutants with high efficiency.The main research contents and results are as follows:（1）For the preparation and optimization of Zn Fe2O4-Ti O2/Ba Ti O3catalysts,the catalysts were prepared by precipitation and sol-gel method,and the optimum value of each factor were optimized by Plackett-Burman test and Box-Behnken response surface method,the mass ratio of Ba Ti O3to Zn Fe2O4-Ti O2was 34.50%,the p H was 1.41,the calcination temperature was 537℃and the 1 h degradation rate of tetracycline under this condition was86.15%.（2）For the characterization of Zn Fe2O4-Ti O2/Ba Ti O3catalysts,the structural morphology and physicochemical properties of the materials were characterized by XRD,SEM,EDS,FT-IR,XPS,UV-Vis,VSM,etc.The XRD patterns indicated that the samples were tetragonal phase Ba Ti O3,spinel-type Zn Fe2O4and anatase phase Ti O2.SEM images showed the sample as a homogeneous sphere with a diameter of 1～2μm,with a rough surface and well-dispersed.UV-Vis DRS showed that the absorption threshold of the sample was significantly red-shifted,which broadened the absorption range of light.VSM magnetization curve indicated that the material was superparamagnetic.Combined with the results of XRD,EDS,FT-IR and XPS analyses,the composite catalyst was successfully fabricated.（3）To study the degradation effect of tetracycline by Zn Fe2O4-Ti O2/Ba Ti O3,degradation tests were conducted using xenon lamp and sunlight as light sources with tetracycline as the target contaminant.The results showed that the best performance was achieved at a catalyst dosage of 1.0 g/L,initial TC concentration of 10 mg/L,p H of 7,and stirring rate of 600 r/min.In addition,the highest degradation efficiency of TC was achieved when ultrasound and agitation were used in combination during sunlight exposure,with 1 h degradation rate of 99.46%.（4）In view of the mechanistic analysis of piezoelectric-photocatalytic degradation of tetracycline,comparison of the inhibition of degradation of tetracycline by the action of different capture agents to investigate the various reactive groups generated and the reaction mechanism resulted in h+,·OH and·O2—as the main reactive substances in the catalytic reaction.（5）For the stability and regeneration study of catalysts,the catalysts were separated from the solutionby cycle experiment,and eight cycle tests were performed,all with degradation rates exceeding 75%and recovery rates remaining at about 90%,proving that the catalyst had good recyclable stability and magnetic recovery properties.For the regeneration study,four different methods after the degradation,and the best catalytic improvement was achieved by hydrogen peroxide treatment,followed by alkali treatment. |
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