Preparation And Photocatalytic Performance Of Na₂Ti₆O₁₃ And Na₂Ti₆O₁₃/TiO₂Nanocatalysts

Environmental pollution and energy shortage become the obstacles of the continualdevelopment of human being, and photocatalytic technology has attracted wide attention onenvironmental treatment. Na₂Ti₆O₁₃is a function material widely used in the fields ofmaterialogy, photoelectricity, environmentology etc. And it can be synthesised into1Dnanomaterials,so, the photocatalytic activity of Na₂Ti₆O₁₃has important significance forpractical application of photocatalytic technology.In this dissertation,1D Na₂Ti₆O₁₃nanobelts and Na₂Ti₆O₁₃/TiO₂composite catalyst wereprepared by the combination of reverse microemulsion method and molten salt method, theirUV photocatalytic activity and kinetic models were studied systematically, and the effects ofreaction conditions on photocatalytic activities were also investigated, in which reactivebrilliant orange X-GN was setted as the target pollutant. The main research contents andconclusions are as follows:At the first,The phase behavior of CTAB/n-hexanol/water reverse microemulsionsystem was investigated by ternary phase diagram analysis and electrical conductivityresearch, and found out the optimum components proportion for preparing nano-precursorTi（OH）₄, whose mass fraction are9.6%（CTAB）,86.8%（n-hexanol） and3.6%（water）.Furtherly, the precursor Ti（OH）₄was characterized by SEM, TG-DSC, FT-IR and XRD, Theresults showed that the precursor are “droplet-shape” particles, whose particle size is about100nm, and their surface have some residual organics.Then the precursor and Na₂CO₃were used to fabricate1D Na₂Ti₆O₁₃nanobelts bymolten salt method. The Na₂Ti₆O₁₃nanobelts obtained by heating at810℃and holding atthis temperature for6h achieved the best photocatalytic activity, and they are1D nanomaterials whose length are5-8μm, when their width and thickness are less than80nm.Na₂Ti₆O₁₃/TiO₂composite catalysts were prepared by reverse microemulsion method andmolten salt method respectively, and the samples were evaluated by XRD, SEM andphotocatalytic tests, the results revealed that the catalysts composited by reverse microemulsion method showed better photocatalytic activity, and RM_1.5-Na₂Ti₆O₁₃/TiO₂is thebest among them. In contrast, the products prepared by molten salt method showed badcatalytic effect.At last, the photocatalytic degradation experiments of X-GN were conducted underUV-light, and the degradation rate, mineralization rate, kinetic models and UV-VIS spectrumswere studied systematically, the results showed that the degradation processes, which werecatalyzed by RM_1.5-Na₂Ti₆O₁₃/TiO₂, M₈₁₀-Na₂Ti₆O₁₃and MS_7:1-Na₂Ti₆O₁₃/TiO₂, fit the firstorder kinetic model, RM_1.5-Na₂Ti₆O₁₃/TiO₂have the best performance among them, whileM₈₁₀-Na₂Ti₆O₁₃have some intermediate products accumulation. Furthermore, the effects ofdifferent reaction conditions were also studied in photocatalysis reactions catalyzed byRM_1.5-Na₂Ti₆O₁₃/TiO₂and M₈₁₀-Na₂Ti₆O₁₃, the results demonstrated that the optimum initialpH value of RM_1.5-Na₂Ti₆O₁₃/TiO₂and M₈₁₀-Na₂Ti₆O₁₃is3.2and5.7respectively; A positivecorrelation existed between the degradation rate and photocatalyst dosage within proper range,but it turned to the opposite trend when the dosage exceeded a certain limit; The degradationrate and the initial X-GN concentration had an inverse correlation; The addition of H₂O₂canobviously improve the degradation efficiency.