Search Results (14)

The present investigation introduces a novel approach, using As-Zn-Fe mining tailings (MT) and recycled bottle glass (cullet) to enable the manufacturing of a new glass for ornamental articles, with characteristics similar to those of soda–lime–silicate glass (SLS), and at the same time, immobilizing potentially toxic elements (PTEs) from mining tailings, which cause environmental pollution with severe risks to human health. The glass used was obtained from transparent glass bottles collected from urban waste, which were later washed to remove impurities and then crushed until they reached No. 70 mesh (212 μm) level; in the case of mining tailings, the sample used comes from the ore benefit process, with 96.8% of particles below the No. 50 mesh level (300 μm). Six mixtures were made by varying the composition of the mining tailings and glass, K₂CO₃ and H₃BO₃ as fluxes were also used in constant proportion. The mixtures were melted at 1370 °C, and later, the glass samples were cast on a steel plate at room temperature. The characteristics of the glasses were studied using thermal analysis (TA), X-ray diffraction (XRD), Fourier transform infrared (FTIR), and scanning electron microscopy (SEM). Likewise, their chemical resistance in acid and basic media and density were evaluated. The results unequivocally demonstrate the feasibility of manufacturing glasses with a light green color, the increase in the content of mining tailings increased the apparent T_g from 625 to 831 °C. Glasses with 17 and 21.3% MT presented lower density values due to a better-polymerized glass structure, attributed to the increase in SiO₂ and Al₂O₃ and the decrease in alkaline oxides, which allowed for the retention of PTEs in their structure. Full article

The ceramics industry has consistently applied circular economy principles by efficiently reusing and recovering raw materials in the production process. Incorporating secondary raw materials, such as production scraps and recycled materials, reduces costs and improves sustainability. In the ceramics sector, raw materials like feldspars can be substituted with secondary raw materials from other production processes, particularly glass-based ones. This study selected waste glass, such as bottle glass or glass fiber processing scraps, to investigate its performance in a porcelain stoneware slab mixture. The behavior of this mixture was compared to a traditional porcelain stoneware mixture and a mixture containing a glass-ceramic frit, which exhibits significantly different behavior from waste glass. The study involved a comprehensive characterization of the fired samples, with a specific focus on addressing pyroplastic deformation—an issue that occurs in large slabs during the firing process. Although pyroplastic deformation has been extensively studied in the past using various waste glasses, this research work uniquely employed waste glass fiber and glass-ceramic material to mitigate pyroplastic deformation compared to the more commonly studied waste soda–lime glass. The pyroplastic deformation tests were conducted using an instrument from Expert Lab Service-MDF. Full article

Recycled soda-lime glass powder is a sustainable material that is also often considered a filler in cement-based composites. The changes in the surface properties of the glass particles due to the treatments were analyzed by X-ray photoelectron spectroscopy (XPS) and optical spectroscopy. We have found that there is a relatively high level of carbon contamination on the surface of the glass particles (around 30 at.%), so plasma technology and thermal annealing were tested for surface cleaning. Room temperature plasma treatment was not sufficient to remove the carbon contamination from the surface of the recycled glass particles. Instead, the room temperature plasma treatment of recycled soda-lime glass particles leads to a significant enhancement in their room temperature photoluminescence (PL) by increasing the intensity and accelerating the decay of the photoluminescence. The enhanced blue PL after room-temperature plasma treatment was attributed to the presence of carbon contamination on the glass surface and associated charge surface and interfacial defects and interfacial states. Therefore, we propose blue photoluminescence under UV LED as a fast and inexpensive method to indicate carbon contamination on the surface of glass particles. Full article

The present research work focuses on the characterization and leachability evaluation of electric arc furnace dust (EAFD) and its vitreous outgrowths produced during vitrification with soda lime recycled glass (SLRG). EAFD is a hazardous industrial waste generated in the collection of particulate material during the steelmaking process via an electric arc furnace. Glasses of various syntheses were obtained during EAFD vitrification with various amounts of silica scrap (50, 60 and 70 wt%). The characterization of the as-received dust was carried out by using granulometry analysis, chemical analysis, X-ray diffraction (XRD), and scanning electron microscopy (SEM), in conjunction with Energy Dispersive X-ray Spectroscopy (EDS). The produced glasses during vitrification were studied by means of chemical and mineralogical analysis, whereas their microstructure in polished sections was examined by SEM/EDS. Their behavior during leaching was determined by the EN 12457-2 compliance leaching test and according to the results, the trace elements detected in the leachates were well below the corresponding regulatory limits. Full article

In this study, a glassy borosilicate compound was synthesized using recycled glass and natural clays. Even though glass recycling is the generally accepted standard practice for managing glass waste, fine fractions of container soda-lime glass or cullet of other compositions are still disposed of in landfills. Thus, advanced upcycled products that offer greater economic motivation for implementation in industry may be the key to success, but these are frequently linked to alternative methods of product synthesis. Here, a simple and facile route of borosilicate compound production has been synthesized and characterized. The physicochemical characterization of the compounds was carried out to determine their properties and the antibacterial efficacy of the synthesized compound against Escherichia coli (E. coli) was investigated. The structural and spectroscopic characteristics were identified as a compound that conformed to quartz, cristobalite, and silicon hexaboride (SiB₆). For the antibacterial activity, two test types were typically performed; in the first one, the dilutions of the grind were combined with chloramphenicol at a concentration of 20 µg/mL to perform a synergistic action against the bacteria and in the second one, only the amorphous borosilicate compound was tested against E. coli ATCC 25922 strains. The treatments applied considered the dilutions from 8 to 40 µg/mL. The minimum inhibitory concentration (MIC) sensitivity tests began with incubation at 37 °C in the tubes and subsequent seeding in Petri dishes for colony-forming unit (CFU) counting. The results obtained indicated that the samples possessed a productive antibacterial effect, which support their use in various biomedical applications. Full article

Glass is made from sand—a finite resource. Hence, there is a need to maintain glass in the industrial cycle as described in the Ellen MacArthur Foundation’s circular-economy diagram. This research project examines the reallocation of material resources in the form of waste glass fines from the industrial recycling process for soda-lime glass. According to the plant manager of Reiling Glasrecycling Danmark ApS, the fines are currently sold to be used for insulation. Although this process prolongs the lifespan of the fines before they become landfill waste, a closed-loop circular option would be preferable. In order to establish a closed-loop circular model for waste glass fines, this research investigates their material and aesthetic qualities and proposes a strategy for maintaining the fines in the closed loop cycle together with the soda-lime glass. The fines are manipulated through robotic deposition and formed into 3D geometries. To expand the aesthetic applications for the material, an investigation is conducted by combining 3D geometries with the traditional glassmaking techniques of glassblowing and casting. The research contributes knowledge of the materials’ technical qualities including printability, durability and workability of the 3D prints combined with cast or blown recycled container glass as well as with blown waste glass fines. Technical obstacles are revealed and alternative routes for further explorations are suggested. Finally, the performative and aesthetic qualities of the results are discussed, while artistic applications for recycled soda-lime glass fines remain to be explored in future research. Full article

Because of the increasing demand for photovoltaic energy and the generation of end-of-life photovoltaic waste forecast, the feasibility to produce glass substrates for photovoltaic application by recycling photovoltaic glass waste (PVWG) material was analyzed. PVWG was recovered from photovoltaic house roof panels for developing windows glass substrates; PVWG was used as the main material mixed with other industrial waste materials (wSG). The glass was casted by air quenching, annealed, and polished to obtain transparent substrates samples. Fluorine-doped tin oxide (FTO) was deposited as back contact on the glass substrates by spray pyrolysis. The chemical composition of the glass materials was evaluated by X-ray fluorescence (XRF), the thermal stability was measured by differential thermal analysis (DTA) and the transmittance was determined by UV-VIS spectroscopy. The surface of the glass substrates and the deposited FTO were observed by scanning electron microscopy (SEM), the amorphous or crystalline state of the specimens were determined by X-ray diffraction (XRD) and the sheet resistance was evaluated by the four-point probe method. The sheet resistance of the deposited FTO on the wSG substrate was 7.84 ± 3.11 Ω/□, lower than that deposited on commercial soda-lime glass (8.48 ± 3.67 Ω/□), meaning that this material could present improved conduction of the produced electrons by the photovoltaic effect. This process may represent an alternative to produce glass substrates from waste materials that could be destined for photovoltaic applications, especially the production of ecological photovoltaic windows. Full article

Fireproof inorganic coatings based on sodium silicate solution with intumescent additions were prepared and tested to assess their ability to limit the negative effect of a fire. The intumescent materials were obtained by the alkali activation of waste glass powder (obtained by the grinding of recycled soda-lime culet) and slag (waste resulting from the metallurgical industry). The replacement of talc (used as filler in paint formulation) with the intumescent materials obtained by the alkaline activation of waste glass powder (WGP), determined an increase in the intumescence coefficient (up to 65%) and decreased the activation temperature of this process. To evaluate these coatings’ abilities to prevent or delay the temperature increase in metal structures, the paints were applied on steel plates and tested in direct contact with the flame of a butane burner for 60 min. The coatings prevented the increase in the steel substrate temperature over one considered critical (500°C) for steel mechanical properties; the combination of two coatings, with different intumescence activation temperatures, correlated with the increase in the coating’s thickness, sensibly reduced the rate of temperature increase (up to 75%) in the steel substrate. Full article

This study reports the results obtained on seventeen glass finds collected from the archaeological site of Muricelle near Cosenza in Calabria (Italy), dated between the first and third century AD. Chemical characterization was undertaken by using an electron probe micro analyser (EPMA). The glasses showed a soda–lime–silica composition indicating the use of the natron as a flux. The comparison between the collected data and those on coeval finds available from the literature allowed us to subdivide the Muricelle glass into three compositional groups: (1) Mn_a, classified as Roman-Mn glasses; (2) Mn_b, which can be compared to the Mn-unintentionally coloured Roman glasses; and (3) Sb + Mn, obtained by the recycling of the Sb and Mn Roman-type glasses. These groups were different not only with respect to the contents and the types of decolourants but also for soda, lime, and aluminium contents, highlighting the use of different raw materials in the primary glass production and also indicating the procedures used in secondary glass production. The compositional characteristics suggested the Levant region as the primary glass source for the Mn_a and Mn_b groups. On the other hand, the Sb + Mn group was obtained through recycling, involving the melting and mixing of two types of primary glass (Sb-decolourised and Mn-decolourised) of Egyptian and Levantine origins, respectively. Full article

The present work shows the path towards the industrial production of ceramic tiles containing a high amount of recycling materials in the substitution of natural raw materials. Starting from the applied research at laboratory scale, which is able to demonstrate the work feasibility, other important milestones consist of pilot scale production until the proper industrial production. Finally, when all these steps are positively achieved, the practice is consolidated and it is possible to reach the concrete sustainability benefits (social, environmental and economic). The results of an industry driven project that aimed to produce porcelain stoneware tiles containing 85% of recycled materials were selected to show this path. This innovative ceramic product—containing soda-lime scrap glass from urban-separated collection (post-consumer waste) and unfired scrap tiles from industrial ceramic process (pre-consumer waste)—was sintered about 200 °C lower than a traditional porcelain stoneware tile. It maintains high technical performances belonging to class BIa of the International Standard of ceramic tile classification (EN ISO 14411). Moreover, this product fulfils the standard requirements for dry-pressed ceramic tiles with low water absorption (≤0.5%), and it obtained the certification UNI Keymark. The LCA study was also performed and the results showed a significantly lower environmental impact of this innovative product compared to a traditional porcelain stoneware tile. Full article

This study aims to provide a thermophysical characterization of a new economical and green mortar. This material is characterized by partially replacing the cement with recycled soda lime glass. The cement was partially substituted (10, 20, 30, 40, 50 and 60% in weight) by glass powder with a water/cement ratio of 0.4. The glass powder and four of the seven samples were analyzed using a scanning electron microscope (SEM). The thermophysical properties, such as thermal conductivity and volumetric specific heat, were experimentally measured in both dry and wet (water saturated) states. These properties were determined as a function of the glass powder percentage by using a CT-Meter at different temperatures (20 °C, 30 °C, 40 °C and 50 °C) in a temperature-controlled box. The results show that the thermophysical parameters decreased linearly when 60% glass powder was added to cement mortar: 37% for thermal conductivity, 18% for volumetric specific heat and 22% for thermal diffusivity. The density of the mortar also decreased by about 11% in dry state and 5% in wet state. The use of waste glass powder as a cement replacement affects the thermophysical properties of cement mortar due to its porosity as compared with the control mortar. The results indicate that thermal conductivity and volumetric specific heat increases with temperature increase and/or the substitution rate decrease. Therefore, the addition of waste glass powder can significantly affect the thermophysical properties of ordinary cement mortar. Full article

Material from the electric arc furnace smelting of municipal solid waste incineration (MSWI) bottom ash was easily converted into highly porous glass-ceramics by a combination of inorganic gel casting and sinter-crystallization at 1000 °C. In particular, the gelation of aqueous suspensions of fine glass powders, transformed into “green” foams by intensive mechanical stirring, occurred with a limited addition of alkali activator (1 M NaOH). The products coupled the stabilization of pollutants with good mechanical properties (e.g., compressive strength approaching 4 MPa). Interestingly, they could be used also as raw material for new glass-ceramic foams, obtained by the same gel casting and sintering method, with no degradation of chemical stability. Limitations in the crushing strength, derived from the limited viscous flow densification of semi-crystalline powders, were overcome by mixing powders from recycled foams with 30 wt% soda-lime glass. The new products finally featured an even higher strength-to-density ratio than the foams from the first cycle. Full article

A new technique for the production of glass foams, based on alkali activation and gel casting, previously applied to soda-lime glass, was successfully extended to boro-alumino-silicate glass, recovered from the recycling of pharmaceutical vials. A weak alkali activation (2.5 M NaOH or NaOH/KOH aqueous solutions) of fine glass powders (below 70 µm) allowed for the obtainment of well-dispersed concentrated aqueous suspensions, undergoing gelation by treatment at low temperature (75 °C). Unlike soda-lime glass, the progressive hardening could not be attributed to the formation of calcium-rich silicate hydrates. The gelation was provided considering the chemical formulation of pharmaceutical glass (CaO-free) to the formation of hydrated sodium alumino-silicate (N-A-S-H) gel. An extensive direct foaming was achieved by vigorous mechanical stirring of partially gelified suspensions, comprising also a surfactant. A sintering treatment at 700 °C, was finally applied to stabilize the cellular structures. Full article

The recycling of waste glass is a major problem for municipalities worldwide. The problem concerns especially colored waste glass which, due to its low recycling rate as result of high level of impurity, has mostly been dumped into landfills. In recent years, a new use was found for it: instead of creating waste, it can be recycled as an additive in building materials. The aim of the study was to evaluate the possibility of manufacturing sustainable and self-cleaning cement mortars with use of commercially available nanomaterials and brown soda-lime waste glass. Mechanical and bactericidal properties of cement mortars containing brown soda-lime waste glass and commercially available nanomaterials (amorphous nanosilica and cement containing nanocrystalline titanium dioxide) were analyzed in terms of waste glass content and the effectiveness of nanomaterials. Quartz sand is replaced with brown waste glass at ratios of 25%, 50%, 75% and 100% by weight. Study has shown that waste glass can act as a successful replacement for sand (up to 100%) to produce cement mortars while nanosilica is incorporated. Additionally, a positive effect of waste glass aggregate for bactericidal properties of cement mortars was observed. Full article