The aim of this research was to study the feasibility of producing sintered nepheline glass-ceramic through a fast firing route. The thermal behaviour of the original glass was analyzed by mean of differential scanning calorimetry (DSC) and X-ray diffractometry (XRD). The microstructural analysis of glass-ceramic materials was carried out by field-emission scanning electron microscopy (FE-SEM). The results showed that the studied wastes are able to produce a glass and glass-ceramic materials through a sinter-crystallization process, 100 µm being the critical glass particle size.Glass-ceramics are composed of residual glassy phase and crystalline phases such as nepheline (NaAlSiO 4 ), augite (Ca, Na)(Mg, Fe, Al)( Si, Al) 2 O 4 and a solid solution belonging to the melilite group (Ca, Na)(Al, Mg, Fe,)( Si, Al) 2 O 7 . In a first evaluation, water absorption (0.02%) and bending strength (71MPa) of glass-ceramic achieved after thermal treatment at 1100ºC/5min suggest that sintered glass-ceramics can be easily produced from coal fly ash and metallurgical slag wastes by a fast-firing cycle and they are extremely serviceable for outdoor flooring and wall cladding.
This paper reports an Alkali-Activated Materials (AAM) using two different precursors, metakaolin and a metallurgical slag with photocatalytic zinc oxide nanoparticles, as novel photocatalytic composites. The photodegradation performance of the composites using methylene blue (MB) dye as a wastewater model was investigated by ultraviolet radiations (UV-vis) spectroscopy. Adsorption in dark conditions and photodegradation under UV irradiation are the mechanisms for removing MB dye. The pseudo-first-order kinetic and pseudo-second-order kinetic models were employed, and the experimental data agreed with the pseudo-second-order model in both cases with UV and without UV irradiations. As new photocatalytic materials, these composites offer an alternative for environmental applications.
The aim of this research was to evaluate the feasibility of using the vitrification process as an alternative solution to the disposal of a coal fly ash and metallurgical slags in landfills. The starting wastes were characterised in terms of chemical, granulometric, mineralogical, and microstructural analysis. A selected batch composition composed by 58.5% fly ash, 31.5% metallurgical slag and 10.0 Na 2 O% (weight percentage) were melted at 1450 °C and poured to obtain monolithic glass samples. The environmental behaviour of the starting wastes and the resulting glass was evaluated by standard leaching tests, which shows that vitrification leads to a stabilization process in which the inorganic components of the wastes are immobilized throughout their incorporation into the glass structure. Moreover, vitrification transforms those hazardous wastes into a new non-hazardous glass. A preliminary study shows that the new glass is suitable for developing glass-ceramic tiles appropriate for floor pavement and wall covering.
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