Construction And Application Of Fluorescent Composite Materials Of 1:1 Type Layered Silicate Minerals

1:1 type layered silicate mineral has a large specific surface area and abundant surface charge due to its special nanostructure,and has broad application prospects in the fields of coatings,pollutant removal,environmental detection and other fields.Organic fluorescent molecules have excellent performance,but the aggregation of fluorescent molecules will cause fluorescence quenching,which significantly affects its luminescence performance and practical applications.The adsorption of organic fluorescent molecules on the surface of layered silicate to construct fluorescent composite materials can effectively solve the problem of concentration quenching.However,the interaction process between 1:1 layered silicate minerals and organic fluorescent molecules and the mechanism of inhibiting fluorescence quenching are not yet fully understood.This paper firstly characterized four typical 1:1 layered silicate minerals halloysite,kaolinite,chrysotile and lizardite,including XRD,SEM,BET,contact angle,Zeta potential,zero point of charge(PZC)and other tests have explored the composition,structure and performance differences of four typical 1:1 layered silicate minerals.On this basis,the adsorption process and influencing factors of 1:1 layered silicate minerals on organic fluorescent molecules were studied.The thermodynamic and kinetic adsorption results of rhodamine B on four silicate minerals of halloysite,kaolinite,chrysotile and lizardite show that the kinetic adsorption processes of rhodamine B on halloysite and kaolinite are in line with the quasi-second-order adsorption model.Combining XRD and Fourier infrared testing and thermodynamic fitting calculation results show that the four 1:1 silicate minerals for rhodamine B conform to the Langmuir adsorption model,indicating that they are all surface monolayer adsorption.This research result provides a theoretical basis for the preparation of mineral/fluorescent composite materials.In this thesis,a 1:1 type layered silicate mineral and rhodamine B fluorescent composite material was prepared,and the fluorescence spectrum,fluorescence lifetime and fluorescence thermal stability were tested,and the influence of mineral structure on the fluorescence performance of the composite material was studied.The relationship between adsorption capacity and fluorescence performance was discussed.The results show that the surface adsorption and dispersion effects affect the fluorescence intensity and fluorescence lifetime of the composite material.The prepared halloysite/rhodamine B fluorescent composite material was applied to the detection of formaldehyde solution.The results show that in the detection range of formaldehyde solution concentration of 2.5 ?mol/L to 15 ?mol/L,there is a certain relationship between formaldehyde concentration and fluorescence intensity,which can provide theoretical basis and technical support for the fluorescence sensor detection of formaldehyde.