Construction Of Several Composite Photocatalysts And Activity For Phenol Degradation Under Simulated Sunlight

In recent years,with the improvement of Chinese environmental protection standards,phenolic compounds have been listed as one of the most important pollutants to be controlled due to their high toxicity and difficulty in degradation.In the modern coal chemical production process,the low concentration of phenol-containing wastewater is the most common,so its purification and treatment is imminent.Photocatalytic oxidation technology has attracted extensive attention in solving the environmental problems of low concentration phenol-containing wastewater due to its advantages of green,environmental protection and high efficiency.Therefore,the invention of high-performance photocatalysts has become the key to the precise treatment of industrial low-concentration phenol-containing wastewater.This paper mainly designs and constructs a series of composite photocatalysts,such as La₂AlFeO₆/ZnO?La₂AlFeO₆/BiOBr?kaolin/ZnO and kaolin/TiO_2?We mainly explored the catalytic performance and cycling stability of the catalysts by degrading phenol under simulated sunlight irradiation.The photocatalysts were characterized by the XRD?XPS?BET?Uv-vis?PL?O₂-TPD?ESR,etc.Overall,The details are as follows:Firstly,a series of La₂AlFeO₆/BiOBr composite photocatalysts were successfully prepared via hydrothermal method,and the La₂AlFeO₆/BiOBr-20%catalyst had the best photocatalytic activity with degradation rate was 95.70%after 5 hours simulated sunlight irradiation,which is 3.20 times of bare La₂AlFeO₆ and 2.20 times of bare BiOBr,respectively.It is considered that the main reason for the best activity of the composite catalyst that it effectively inhibits the recombination of photogenerated electron-hole pairs and the presence of more hydroxyl oxygen and adsorbed oxygen on the surface.Secondly,a series of La₂AlFeO₆/ZnO composite photocatalysts were synthesized by chemical impregnation method.When the composite ratio of La₂AlFeO₆ and ZnO is 1:9,the phenol removal rate is 94.10%after simulated sunlight for 5 hours,which is 3.50 times and 1.80 times of the pure phase La₂AlFeO₆and ZnO,respectively.The results of several characterization analyses indicated that the best photocatalytic activity of the composite photocatalyst is mainly attributed to the existence of the hydroxyl oxygen,absorbed oxygen and the higher separation efficiency of photogenerated electron and hole pairs.Thirdly,we prepared kaolin/ZnO catalysts,the catalyst showed better photocatalytic performance when the composite ratio is 1:1,and phenol degradated efficiency is up to 95.80%after 300min irradiation,which is superior to pure kaolin and ZnO.The series characterization analysis showed that the excellent activity is favorable for the larger specific surface area?more narrow band gap and hydroxyl oxygen.Fourthly,kaolin/TiO₂ photocatalysts were prepared by sol-gel method.KT-10have the best phenol degradation activity with 63.50%after 5h simulated sunlight irradiation.Although the phenol degradation efficiency was not good,compared with pure TiO₂ and pure kaolin,the phenol degradation efficiency is increased by 29.70%and 43.40%,respectively.The study found that the main reason for the increase of composite catalyst activity is due to the increase of hydroxyl oxygen content in catalyst surface.