| Water is the source of life.With the rapid development of modern industry and the improvement of people’s living standards,the problem of water environment and water ecological pollution has become increasingly serious and has received more and more attention,which has promoted the continuous development of various water treatment technologies,such as physical adsorption,chemical oxidation and microbial treatment.In recent years,photocatalysis technology,as an advanced oxidation technology,has played an increasingly important role in the field of environmental remediation and energy conversion,but its practical application effect is still limited by many conditions.The core of photocatalysis technology is photocatalyst,so the development of new and efficient photocatalyst to play its role in the field of water pollution control has become the research focus of many scholars at home and abroad.Since Professor Fujishima found that TiO2 can decompose water to generate hydrogen under ultraviolet irradiation,TiO2 has been widely used in the field of photocatalysis because of its good chemical stability,non-toxicity and low cost.However,TiO2’s wide band gap and high photogenerated carrier recombination rate greatly limit its application in visible light.Perylene diimide and its derivatives（PDIs）have large planar ringπ-electron conjugation structure,wide light absorption range and excellent photothermal stability.They are ideal sensitizers for visible light response.These advantages make them the first choice for high-quality dyes.However,PDIs have strong rigidity and poor water solubility,and can only be dissolved in concentrated sulfuric acid or m-cresol,which greatly limits the interaction between PDIs and some inorganic semiconductors.Therefore,water-soluble perylene diimide naphthalenesulfonic acid（PDI-NapSO3H）was designed and synthesized in this paper,which interacted with metal iron doped TiO2 to obtain a new type of composite photocatalyst Fe-TiO2@PDI-NapSO3H with visible light activity.The degradation performance of the composite photocatalyst for phenol and sodium diclofenate under visible light was investigated.And compared with other reported materials,the results showed that the Fe-TiO2@PDI-NapSO3H composite photocatalyst prepared in this paper has superior photocatalytic performance.The specific work is as follows:（1）The water-soluble PDI-NapSO3H was synthesized by the reaction of 5-amino-2-naphthalene sulfonic acid and perylene-3,4,9,10-tetracarboxylic anhydride,and its molecular structure was determined by nuclear magnetic resonance spectroscopy（1H NMR）and high-resolution mass spectrometry（HRMS）.The composite photocatalyst TiO2@PDI-NapSO3H was synthesized by the reaction of PDI-NapSO3H and Fe-TiO2.Using phenol as a probe,the effects of the loading amount of PDI-NapSO3H,hydrothermal temperature,hydrothermal time and the amount of composite photocatalyst on the degradation efficiency of composite photocatalyst were investigated,and the optimum preparation conditions of composite photocatalyst Fe-TiO2@PDI-NapSO3H were determined.（2）The functional group characteristics,morphology and crystal form of the composite photocatalyst were characterized by infrared spectrum（FTIR）,Raman spectra（Raman）,X-ray photoelectron spectroscopy（XPS）,transmission electron microscope（TEM）,high power transmission electron microscope（HRTEM）and X-ray powder diffraction spectrum（XRD）,which proved that the composite photocatalyst was successfully prepared.（3）The efficiency,kinetic characteristics,cycle stability and universality of the composite photocatalyst for the degradation of phenol and diclofenac sodium were investigated.The degradation process of diclofenac sodium and its products were thoroughly studied in combination with high-resolution mass spectrometry,and the possible degradation pathway was proposed.The toxicity of the pollutant solution before and after the photocatalytic reaction was evaluated by the luminescent bacteria experiment.（4）The separation efficiency of photo-generated carriers was characterized by fluorescence spectrum,photocurrent density and electrochemical impedance spectroscopy.The species and quantity of free radicals were determined by free radical capture experiment and electron spin test.The direction of electron transfer was determined by ultraviolet photoelectron spectroscopy.Combined with energy band position analysis,the possible photocatalytic mechanism of composite photocatalyst was proposed. |
