Preparation Of Iron Oxide Carbon-based Photo-Fenton Catalysts And Their Performance

How to effectively remove toxic and harmful organic pollutants in water has been the hot issue of concern in water treatment.The heterogeneous Fenton process based on iron oxides which can generate strong oxidizing hydroxyl radicals?·OH?and is easy to operate,is recognized as a promising advanced oxidation technology for water purification.However,the ferrous ions on the surface of solid catalysts are difficult to regenerate under neutral conditions,resulting in low reaction efficiency.Therefore,it is urgent to develop more efficient catalysts.In this paper,through combining iron-based oxides with functional hydrothermal carbon materials which contain oxygen-containing groups on surface,three new types of iron oxide carbon-based catalytic materials were synthesized by the hydrothermal method and immersion precipitation method.We constructed several visible light-assisted heterogeneous Fenton systems with synergistic effect of multi-components,which could effectively accelerate the regeneration of Fe²⁺and promote to catalyze the decomposition of H₂O₂ to produce active oxygen species for the degradation of organic pollutants in water.The effects of different preparation conditions,reaction conditions and carbon-based materials on the system were studied,and the reaction mechanism of the system was explored.The specific studies include the following three parts:?1?In this chapter,a series of iron oxide/hydrothermal carbon composites?Fe/HC?were synthesized by a hydrothermal method.The structure,composition and chemical state of the obtained samples were analyzed by different characterization methods.The effect of precursor pH on the structure and catalytic properties of the obtained samples was studied.Using Orange II as simulated pollution,the Fenton catalytic activity of different Fe/HC samples under visible light irradiation was investigated.The results showed that the catalytic activity of Fe/HC-2 prepared at pH2 was the highest.It is found that visible light could promote the leaching of Fe²⁺and Fe³⁺,and could accelerate the regeneration of Fe²⁺,so that the system continuously produced·OH for the efficient degradation of orange II.Cycling performance tests proved that the Fe/HC-2 catalyst had good reusability.?2?In this chapter,iron-zinc oxide/hydrothermal carbon composites?Fe-Zn/HC?was one-pot synthesized by a hydrothermal method and used as a heterogeneous photo-Fenton catalyst for the degradation of phenol in water.The effects of p H value,concentration of H₂O₂and phenol on the degradation efficiency of the system were investigated.Meanwhile,the roles of surface Fe²⁺,photogenerated electrons and·OH in this photo-Fenton process were explored.The results indicated that Fe-Zn/HC catalyst exhibited high photo-Fenton activity for the degradation of phenol.·OH is the main active species in this system.Photogenerated electrons produced from Fe-Zn/HC under visible light irradiation accelerated the regeneration of surface Fe²⁺and the formation of·OH.?3?Based on the hydrothermal carbonization process of glucose,in this chapter,two types of hydrophilic and functional carbon spheres were synthesized under acid?pH2?and alkaline?p H10?condition,respectively,and would compare with commercial active carbon nanoparticles.Iron oxides were loaded on the three kinds of carbonaceous materials by moderate immersion precipitation method.It was found that the iron oxides growing on hydrochar microspheres?HCM?was assigned to?-FeOOH,?-Fe₂O₃ were grown on other two carbon-based spheres.Using Orange II as simulated pollutant,the effects of three kinds of composites on catalytic performance for the degradation of Orange II in the simultaneous presence of H₂O₂ and visible light irradiation were studied.The catalytic mechanism of HCM@FeOOH in the degradation process of pollutants was explored emphatically.The results showed that HCM@FeOOH with core-shell structure exhibited the highest catalytic activity.Photogenerated holes and·O₂^-played important roles in this process,and·O₂^-was mainly produced from the reaction between holes and H₂O₂.Orange II was degraded by holes and·O₂^-in this system.