Synthesis of new Cr2O3/Fe2O3/glass composites from industrial wastes; from undesired to advanced optical products.

For the tendency toward cleaner production and safe conversion of undesired toxic wastes to highly priced advanced products, this work introduces new ceramics/glass composites of Cr2O3/Fe2O3/lead silicate glass (LSG) from industrial LSG wastes. Both chromia Cr2O3 and hematite Fe2O3 ceramics are added equally to the LSG wastes with different percentages (10, 20, and 30 wt.%) via the pressureless sintering method. The competitiveness of this work is dependent on the conversion of undesired waste materials into advanced/smart optical materials with a low cost and an environmentally friendly method. Hence, the influence of both Cr2O3 and Fe2O3 additions on the behavior and the different characteristics of the lead silicate wastes are comprehensively investigated. Evaluation of the final ceramics/glass composites was achieved through their phase composition, microstructure, optical, and magnetic characteristics. The results verified that the insertion of both chromia and hematite together into the glass waste had a key role in improving its morphological properties and optical and magnetic behaviors. Composite with 30% of Cr2O3/Fe2O3 gave the highest optical absorbance of 90%, the lowest and best band gap energy of 1.68 ev, and the highest refractive index of 2.85. Also, it recorded the best magnetic behavior with the highest saturation magnetization of 139.700 × 10-2A m2 kg-1 and the best coercivity of 190.0 Oe. These findings confirmed the successful clean conversion of the hazardous lead silicate waste into advanced products with promising optoelectronic characteristics.

Zinc ferrite nanoparticles from industrial waste for Se (IV) elimination from wastewater.

The presence of high concentrations of selenium ions in wastewater is considered an environmental problem. However, the mechanism of selenium ions (Se (IV)) removal by the adsorption process has not been investigated in-depth so far. Also, the recovery and conversion of the industrial waste materials into valuable materials is a vital issue. Therefore, in this study, zinc ferrite nanopowders are economically synthesized from steel-making wastes by co-precipitation method for investigating as adsorbents of selenium species. The produced nanopowders were annealed at 150, 300, 500, and 850 °C for 5 h to scrutinize the impact of annealing temperature on their crystallite size. The compositional, optical, and magnetic features of the nanopowders were defined by X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM), UV-Vis. spectrophotometer along with vibrating sample magnetometer (VSM). Optical absorbance spectra were found characteristic due to the electronic structure of Fe3+ (3d5) considering the C3v local symmetry of Fe3+ ions. The prepared nanopowders demonstrated good adsorption capacity toward selenium ions (43.67 mg/g at pH 2.5) from an aqueous medium. Adsorption data were found fitting to Freundlich isotherm model. Thus, ZnFe2O4 can be recommended to effectively eliminate selenium ions from aqueous solutions.

Combined effect of magnesia and zirconia on the bioactivity of calcium silicate ceramics at C\S ratio less than unity.

This paper describes the effect of magnesia in the presence of zirconia on the bioactivity, microstructure and physico-mechanical properties of calcium silicate composition adjusted at calcia/silica ratio(C/S) of 0.5. A mixture from calcium carbonate and silica was conducted at C/S of 0.5. 20wt.% of magnesia and 5-25wt.% of ZrO2 were added. Each mixture was mixed with ethanol in a planetary ball mill, dried, formed and fired at a temperature of 1325±5°C. Phase composition, FE-SEM, and physico-mechanical properties of the fired specimens were determined and explained. The in vitro bioactivities of these specimens were investigated by analysis of their abilities to form apatite in the simulated body fluid (SBF) for a short time (7days) using SEM-EDS. The findings indicated that the surface of the specimens containing 5 and 15wt.% ZrO2 were completely covered by single and multilayered hydroxyapatite (HA) precipitate typical to "cauliflower" morphology, respectively. The surface of the specimen containing 25wt.% ZrO2 did not cover, but there are some scattered HA precipitate. The differences among the results were rationalized based on the phase composition. Vickers hardness and fracture toughness of the specimens of highly promised bioactivity were 2.32-2.57GPa and 1.80-1.50MPa. m1/2, respectively. The properties of these specimens are similar to the properties of human cortical bone. Consequently, these composites might be used as bone implant materials.