Preparation And Visible Light Catalytic Properties Of ABO₃/Muscovite Nanocomposites

With the rapid development of industry,water pollution has become an inevitable global challenge.As a green pollutant degradation technology,semiconductor photocatalysis is expected to solve the above environmental problems.Among them,perovskite oxide semiconductor has a medium band gap and high chemical stability,which has been widely paid attention by scholars.However,due to its weak visible light response,easy recombination of photogenerated electron hole pairs,and small particle size of nano powder,it is not easy to recover and other characteristics,its large-scale practical application is still limited.This paper is based on the fact that the A and B sites of ABO₃ perovskite can hold multiple ions,the basic configuration remains unchanged,but the symmetry and structural parameters are changed.LaNi O₃ perovskite-type oxide photocatalytic material was selected as the basis for doping to reduce the band gap width and broaden the scope of the absorption of light.In addition,Muscovite with relatively flat surface and large specific surface area was used as the composite substrate to make the perovskite evenly dispersed on the muscovite sheet,solve the problem that perovskite oxide easy to agglomerate and difficult to recycle.In this way,the effects of A site,B site and composites on the phase structure,microstructure,photocatalytic activity and antibacterial properties of perovskite oxide were studied.The main research contents are as follows:Firstly,LaNi_1-xB_xO₃（B=Fe,Mn）samples were synthesized by sol-gel method with transition metal element doped at the B site.The phase structure,microstructure,molecular bond energy,optical properties and photocatalytic activity of LaNi_1-xB_xO₃samples were characterized.Results show that the doping of Fe and Mn does not change the structure of perovskite oxide,and does not introduce impurities.LaNi_0.95Fe_0.05O₃and LaNi_0.60Mn_0.40O₃ samples has a better photocatalytic performance.The degradation rates of methyl orange under visible light irradiation for 120 min are 98.9%and 99.5%,respectively,and the degradation rate constants are 0.0270 min^-1and 0.0295 min^-1,which are 1.56 and 1.66 times of that of undoped LaNi O₃(0.0178 min^-1),respectively.Secondly,based on the element composition of B site Ni:Fe=0.95:0.05,A site doping was carried out.La_1-xA_xNi_0.95Fe_0.05O₃（A=Ce,Sr）samples were synthesized by sol-gel method.XRD,SEM,FT-IR were used to characterize the effects of A site doping on the phase structure and microstructure.Results show that A doping will change the space-occupying structure of perovskite oxide,resulting in the failure of Ce and Sr to completely replace La and the introduction of impurity phases,such as Ce O₂,Ni O,La₂O₃,Sr CO₃,and grain size decreases with the increase of doping amount.La_0.90Ce_0.10Ni_0.95Fe_0.05O₃ and La_0.20Sr_0.80Ni_0.95Fe_0.05O₃ samples with high photocatalytic performance of the visible light irradiation,120 min of methyl orange degradation rate were 97.6%and 99.2%,the degradation rate constants were 0.0239 min^-1 and 0.0276min^-1,which were 1.34 and 1.55 times of undoped LaNi O₃(0.0178 min^-1),respectively.Finally,based on the B-site element composition of Ni:Fe=0.95:0.05,muscovite was selected as composite basement,LaNi_0.95Fe_0.05O₃/muscovite composite photocatalytic materials prepared by sol-gel impregnation method,to investigate different amount of muscovite composite on the structure and photocatalytic activity of the sample.The results show that the composite of muscovite has no obvious effect on the phase and structure of LaNi_0.95Fe_0.05O₃.The composite makes the LaNi_0.95Fe_0.05O₃ uniformly dispersed on the surface of muscovite and reducing the agglomerate of LaNi_0.95Fe_0.05O₃.When the ratio of muscovite to LaNi_0.95Fe_0.05O₃ is 1,the degradation rate of methyl orange under visible light irradiation for 120 min is 99.03%.In addition,the antibacterial properties of LaNi_0.95Fe_0.05O₃,LaNi_0.60Mn_0.40O₃ and LaNi_0.95Fe_0.05O₃/muscovite composite photocatalytic materials were investigated.The results showed that the best antibacterial effect of LaNi_0.95Fe_0.05O₃ against Escherichia coli was 88.5%,followed by LaNi_0.60Mn_0.40O₃ with 80.3%,followed by LNFBy-1.00with 77.8%.The antibacterial effect of the three catalysts on Staphylococcus aureus was general,about 65%.