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Synthesis of a novel visible light responsive <i>γ</i> -Fe2O3/SiO2/C-TiO2 magnetic nanocomposite for water treatment
摘要： This work investigates the preparation of a magnetically recoverable photocatalytic nanocomposite of maghemite nanoparticles coated with silica and carbon doped titanium dioxide. The novel nanocomposite boasts the advantages of efficient photocatalytic degradation of organic pollutants in water and ease of recovery of the fine particles after water treatment. The photocatalytic nanocomposite was successfully synthesized through a stepwise approach via co-precipitation and sol-gel methods. Characterisation by FTIR, XRD, TEM and EDS substantiated the existence of the intended structure of the nanocomposite and the particles were found to be in the size range of 15–22 nm with a quasi-spherical shape. BET surface area analysis revealed an average surface area of 55.20 m2/g which is higher than that of commercial TiO2 (Degussa P25, 50.00 m2/g) and an average pore diameter of 8.36 nm. A 5 ppm methylene blue solution was degraded with an efficiency of 96.8% after 3 h of solar irradiation, which was 19.7% greater than using the same photo-catalyst under strict UV light irradiation. Photo-catalysis using these nanoparticles was observed to be very effective. The prepared novel visible light active nanocomposite has great potential for incorporation into water treatment systems because it exhibits good stability and magnetism as well as high photocatalytic efficiency.
关键词： methylene blue,titanium dioxide,water treatment,maghemite,photo-catalysis,magnetic nanocomposite
更新于2025-09-23 15:22:29
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A Novel Despeckling Method for Medical Ultrasound Images Based on the Nonsubsampled Shearlet and Guided Filter
摘要： Porous maghemite (PM) was prepared by two-step calcinations. The crystallographic and magnetic changes of PM upon SO4^2? and CO3^2? adsorption were investigated. The crystallite size (~ 27 nm) and PM texture remain unchanged after adsorption. Fourier transform infrared spectra showed that SO4^2? and CO3^2? are adsorbed on the PM mainly through outer- and inner-sphere surface complexations, respectively. X-ray photoelectron spectra showed the increase and decrease of binding energy for Fe 2p3/2 electrons after SO4^2? and CO3^2? adsorption, respectively. Sulfate adsorption increases the magnetic susceptibility (χ) of PM by ~ 4.5%, and decreases the saturation magnetization (Ms) of PM by 24.6%. By comparison, carbonate adsorption decreases χ by ~ 3.7% and increases Ms by 17.8%. The magnetic changes upon SO4^2? and CO3^2? adsorption are attributed both to the electronegativity of anions and the size distribution of PM.
关键词： Adsorption,Electronegativity,Inorganic anion,Porous maghemite,Magnetic property
更新于2025-09-11 14:15:04