Comparison of Ten Metal-Doped LaFeO3 Samples on Photocatalytic Degradation of Antibiotics in Water under Visible Light: Role of Surface Area and Aqueous Phosphate Ions

Doping semiconducting oxides, such as LaFeO3 (LF), with metallic elements is a good strategy to improve the performance of photocatalysts. In this study, LF and ten different nanopowders metal-doped at the La or Fe site of LaFeO3 were evaluated in the photocatalytic degradation of ciprofloxacin (CP) and oxytetracycline (OTC). The following metals were used in the doping (mol%) process of LF: Pd 3% and 5%; Cu 10%; Mg 5%, 10%, and 20%; Ga 10%; Y 10% and 20%; and Sr 20%. The doped samples were synthetized using a citrate auto-combustion technique. From the X-ray diffraction (XRD) data, only a single crystalline phase, namely an orthorhombic perovskite structure, was observed except for trace amounts of PdO in the sample with Pd 5%. The specific surface area (SSA) ranged from 9 m(2) g(-1) (Ga 10%) to 20 m(2) g(-1) (Mg 20%). SEM images show that all samples were constituted from agglomerates of particles whose sizes ranged from ca. 20 nm (Mg 20%) to ca. 100 nm (Pd 5%). Dilute aqueous solutions (5 x 10(-6) M) prepared for both CP and OTC were irradiated for 240 min under visible-light and in the presence of H2O2 (10(-2) M). The results indicate a 78% removal of OTC with Cu 10% doped LF in a phosphate buffer (pH = 5.0). The degradation of CP is affected by pH and phosphate ions, with 78% (in unbuffered solution) and 54% (in phosphate buffer, pH = 5.0) removal achieved with Mg 10% doped LF. The reactions follow a pseudo-first order kinetic. Overall, this study is expected to deepen the assessment of photocatalytic activity by using substrates with different absorption capacities on photocatalysts

Effect of synthetic route on performance of La0.8Sr1.2Fe0.9Cu0.1O4±δ electrodes for symmetric solid oxides fuel cells

The solid oxide La0.8Sr1.2Fe0.9Cu0.1O4±δ of interest as electrode for Symmetric Solid Oxide Fuel Cells (SSOFCs) has been prepared via three different synthetic methods: solid-state reaction (SSR), melt citrate route (MC) and co-precipitation (CoP). In order to determine advantages and drawbacks of each synthesis, the materials have been characterized by X-Ray Powder Diffraction (XRD) and Scanning Electron Microscopy (SEM) analysis. Phase purity, structural and morphological characteristics of the powders have been determined. Wet chemical methods (CIT and COP) have the advantage over SSR synthesis of yielding small-sized powders (â\u88¼1mu;m); moreover, melt citrate route allows lowering the preparation temperature down to 1000 °C. Electrochemical characterization was performed by Electrochemical Impedance Spectroscopy (EIS) in air in an electrolyte supported symmetric cells configuration. Preliminary results allow to draw some conclusions on the relation between the structural and microstructural characteristics of the powders and the electrochemical performance

Chemistry and microstructure of cement pastes admixed with organic liquids

The influence of organic admixtures on hydration process of cement pastes have been investigated to assess the possibility of immobilizing toxic organic wastes in cement-based materials. The model organic waste used is a mixture of water, methanol and 2-chloroaniline: 100/76/4 volume ratios, respectively. Four pastes were obtained admixing this solution with two different cements (ordinary and white Portland), with weight ratios equal to 0.40 and 0.65, respectively; in addition, cement pastes without organic wastes were prepared (water to cement ratio 0.40). The progress of hydration process of these six series of samples was monitored for the first 8 months of ageing by thermogravimetric analysis; moreover, a detailed microstructural investigation on mature pastes was performed by quantitative X-ray diffraction and scanning electron microscopy. Dynamic leach tests were carried out on samples cured for 28 days, according to the international standards