Photocatalytic Properties Of CaTiO₃Synthesized By Solid-Phase Synthetic Method

In the article, CaTiO3that was the main mineral of the titanium-bearing blast furnace slag was studied.CaTiO3was synthesized by solid-phase synthetic method. Characteristics of CaTiO3absorbing methylene blue under the dark reaction conditions, and effect of preparation conditions on the photocatalytic degradation ability of methylene blue on CaTiO3was discussed.Photocatalytic activity of CaTiO3was evaluated. Doping of metal ions on CaTiO3was studied. Photocatalytic degradation reaction kinetics and mechanism of methylene blue on CaTiO3were preliminarily studied. This will play an important role in studying the photocatalytic properties of the titanium-bearing blast furnace slag, and provide theoretical basis for the slag as photocatalytic materials, and have great significance for its rational use.With CaC03and TiO2as raw materials, CaTiO3was synthesized by solid-phase synthetic method, and effect of the synthetic conditions on composition, morphology and light absorption capacity was systematicly studied. By the analysis of XRD, SEM, FTIR and UV-vis, the results showed that pure CaTiO3can be synthesized above1400℃; with the baking time and temperature to increase, reunion phenomenon of particles was increasingly apparent, and size of particles increased, and morphology of synthetic CaTiO3changed from irregular polygon-shape surface into the smooth surface shape; Baking time affected little the light absorption capacity of CaTiO3; baking temperature by changing solid-phase composition led to be great change in the light absorption capacity of photocatalyst.In the dark reaction conditions, characteristics of CaTiO3absorbing methylene blue were discussed. Effect of dosage of CaTiO3, initial concentration of methylene blue and pH on the adsorption of methylene blue was analyzed. Meanwhile, during the preparation of CaTiO3, effect of baking time and temperature on the photocatalytic ability of CaTiO3was studied.The results showed that the adsorption of methylene blue on CaTiO3was in line with Lungmuir adsorption isotherm, and adsorption capacity was1.699mg/g. Adsorption of methylene blue on CaTiO3was chemical adsorption, which caused chemical reaction. Dosage of CaTiO3had little effect on adsorption of methylene blue on CaTiO3, and adsorption removal rates was between10%to12%; when methylene blue concentration was less, removal rate of methylene blue absorbed by CaTiO3was higher, and with the concentration increasing, removal rate decreased; change of pH affected little on adsorption of methylene blue on CaTiO3, and adsorption rate was between12%-14%. In all conditions, adsorption-desorption equilibrium time was about0.5h. By influencing the morphology, size of CaTiO3particles, baking time affected the photocatalytic properties, and with baking time increasing, degradation rate of methylene blue reduced in the overall trend; baking temperature affected the photocatalytic activities from the solid phase composition, morphology, particles size, and with baking temperature increasing, degradation rate of methylene blue reduced in the overall trend.Effect of illumination time, pH, initial concentration of methylene blue and dosage of CaTiO3on the activity of photocatalytic degradation of methylene blue on CaTiO3under UV-visible light was systematicly studied. The results showed that CaTiO3had ability of photocatalytic degradation; strong alkaline conditions were favor in the photocatalytic degradation of methylene blue solution with CaTiO3; when methylene blue concentration was less, photocatalytic degradation rate of CaTiO3on methylene blue was higher, and when the concentration of methylene blue was1mg·l-1, degradation rate was71.64%after3h; the best dosage of CaTiO3was0.1g; photocatalytic degradation ability of CaTiO3under visible light was about half of ability of CaTiO3under UV-visible light.In modification experiments of CaTiO3doped by Fe3+, effect of the baking temperature and doping content on the photocatalytic properties of CaTiO3was mainly studied. The results showed that when content of Fe3+was0.474%, Ca4Fe2Ti2O11was generated; baking temperature affected little chemical composition, morphology and particle size of Light catalyst, however, baking temperature had great impact on particles agglomeration and absorption capacity, with the increase of baking temperature, ability of photocatalytic degradation first increased, and then reduced. When the baking temperature was500℃, ability of photocatalytic degradation was the highest, and degradation rate of methylene blue that was5mg·l-1was100%. Changes of content of Fe3+led to changing of the chemical composition and light absorption ability of catalysts. Fe3+entered the CaTiO3lattice, and and Fe2O3generated, which changed the ability of photocatalytic degradation of catalysts. The best doping content of Fe3+was0.474%, and degradation rate of methylene blue that was5mg·l-1was100%after3h. Effect of pH, initial concentration of methylene blue, dosage of CaTiO3, preparation conditions and doping on the kinetics of photocatalytic degradation reaction of methylene blue on CaTiO3under UV-visible light was systematicly studied, and reaction mechanism was analyzed. The results showed that the influence of the conditions on the correlation coefficient R2and the apparent rate constant was different, however, the reactions were in line with a reaction kinetics; in the photocatalytic degradation reaction of methylene blue on CaTiO3, photo-O2-and-OH worked, and generation of O2·went through two competitive process.