Preparation Of Perovskite LaCoO₃ Catalyst And Its Photocatalytic Degradation Of Phenol

Phenol is an organic pollutant that is difficult to degrade and has high toxicity.Once it enters the water,it will seriously pollute the surrounding ecosystem and threaten the life and health of organisms to a certain extent.Photocatalytic technology has become one of the most effective ways to degrade phenol wastewater because of its excellent properties such as advanced oxidation function,low price,clean and efficient.Perovskite-type LaCoO₃ photocatalyst had been proved to be an efficient photocatalyst for the removal of organic pollutants from wastewater due to its advantages of good stability,low cost,non-toxicity and environmental friendliness.In this paper,a series of LaCoO₃ perovskite catalysts with different calcination temperatures were synthesized by hydrothermal method,and their structure,morphology and optical properties were characterized by XRD,SEM,TEM,FT-IR,BET,XPS and MPMS.Taking phenol as the target degradation material,the photocatalytic degradation reaction was carried out under visible light irradiation.The universality of LaCoO₃ was explored by degrading other dye wastewater.The experimental results showed that the prepared perovskite catalyst LaCoO₃ had good crystallinity,the particle size of the catalyst were between 10nm and 40 nm,and the specific surface area decreased with the increase of calcination temperature.The catalysts showed strong paramagnetism,and the particles showed regular agglomeration under the action of magnetic force.LaCoO₃ catalyst showed strong photocatalytic activity at the calcination temperature of 750℃.After visible light irradiation at 20℃for 4 h,the degradation rate reached 52.56%.Through the modification of LaCoO₃ catalyst to improve the degradation ability of LaCoO₃ for phenol.Ba metal at position A was doped by hydrothermal method,La_1-xBa_xCo O₃（x=0.2,0.3,0.4,0.5,0.6）was prepared with five different doping ratios,and their structure,morphology and and optical properties were characterized by XRD,SEM,FT-IR,XPS and MPMS.And the photocatalytic reaction of phenol was carried out.The experimental results showed that when the doping ratio of La and Ba was 1:1,the synthesized catalyst had better degradation effect on phenol.After 6 hours of visible light irradiation at 20℃,the degradation rate reached 83.50%,showing good photocatalytic activity.The photocatalytic degradation reaction before and after modification followed the first-order kinetics.In addition,the catalysts still showed excellent photocatalytic activity after five cycle experiments,indicating that the catalysts had good reusability,and the structure of the catalyst had not changed significantly after five repeated experiments according to XRD analysis.The photocatalytic mechanism was studied by free radical capture experiment.IPA,BQ,AO and AgNO₃ were added to the system respectively.The degradation rates of phenol were 26.4%,61.3%,65.7%and 80.9%respectively.The analysis showed that·OH radical played a major role in the degradation of phenol in the process of photocatalytic reaction,and·O₂^-and H⁺played an auxiliary role.