Urea Glass Route as a Way to Optimize YAGG:Ce3+,Cr3+,Pr3+ Nanocrystals for Persistent Luminescence Applications.

A new approach for the synthesis of Y3Al2Ga3O12 (YAGG) nanophosphors allowing the preparation of crystallites with sizes starting from 45 nm is presented. The controllability of the energy and trap density of the resulting material samples by annealing temperature was confirmed by thermoluminescence (TL) measurements. It has been shown that the annealing of samples at temperatures up to 1300 °C does not cause any substantial growth of crystallites, still remaining below 100 nm, but leads to changes in the activation energy of the persistent luminescence (PersL) process. On the other hand, annealing above 1400 °C results in grain growth on the submicron scale, which was confirmed by X-ray powder diffraction (XRPD) and electron transmission microscopy (TEM) measurements. In addition, with an increase in the molar ratio of urea to the total amount of metals used (R), qualitative changes are observed in the PersL process occurring from the excited states of Cr3+ and Pr3+ ions. This proves the influence of the synthesis process, in particular of the metal complexation at its initial stage, on the final structure ordering in the annealed materials. These observations are linked to previously reported defects in the YAGG structure, leading to PersL.

Effect of the Introduction of Reactive Fillers and Metakaolin in Waste Clay-Based Materials for Geopolymerization Processes.

In this study, the role of two reactive fillers, specifically a sand from a clay washing process as an alternative to waste glass powder and a commercial metakaolin (MK), into the geopolymerization process of waste clay-based materials was assessed. Three kinds of clayey wastes from mining operations-halloysitic, kaolinitic and smectitic clays-were tested as potential precursor of geopolymeric materials in view of a potential valorisation of these by-products. A mix-design based on the addition of low percentages (20%) of these fillers or MK to improve the mechanical and chemico-physical properties of geopolymeric formulations was evaluated. All the clays were thermally treated at a temperature of 650 °C, while the geopolymeric pastes were cured at room temperature. In particular, the chemical stability in water (pH and ionic conductivity of leachate water, weight loss), the variations in the microstructure (XRD, SEM), and in the mechanical performance (compressive strength) were analysed. The most reactive additive was MK, followed by sand and waste glass at very similar levels-1:1 or 2:1-depending upon the type of the clay but not strictly related to the clay type. The increase of geopolymeric gel densification due to the presence of MK and sand was replaced by a crack deflection mechanism in the case of the WG grains. The worst performance (chemical stability and mechanical properties) was found for the halloysitic clay, while kaolinitic and smectitic clays developed strengths slightly below 30 MPa.

Green Deep Eutectic Solvents for Microwave-Assisted Biomass Delignification and Valorisation.

Aiming to fulfil the sustainability criteria of future biorefineries, a novel biomass pretreatment combining natural deep eutectic solvents (NaDESs) and microwave (MW) technology was developed. Results showed that NaDESs have a high potential as green solvents for lignin fractionation/recovery and sugar release in the following enzymatic hydrolysis. A new class of lignin derived NaDESs (LigDESs) was also investigated, showing promising effects in wheat straw delignification. MW irradiation enabled a fast pretreatment under mild condition (120 °C, 30 min). To better understand the interaction of MW with these green solvents, the dielectric properties of NaDESs were investigated. Furthermore, a NaDES using the lignin recovered from biomass pretreatment as hydrogen bond donor was prepared, thus paving the way for a "closed-loop" biorefinery process.

Resin-Immobilized Palladium Nanoparticle Catalysts for Organic Reactions in Aqueous Media: Morphological Aspects.

An insight into the nano- and micro-structural morphology of a polymer supported Pd catalyst employed in different catalytic reactions under green conditions is reported. The pre-catalyst was obtained by copolymerization of the metal-containing monomer Pd(AAEMA)2 [AAEMA-=deprotonated form of 2-(acetoacetoxy) ethyl methacrylate] with ethyl methacrylate as co-monomer, and ethylene glycol dimethacrylate as cross-linker. This material was used in water for the Suzuki-Miyaura cross-coupling of aryl bromides, and for the reduction of nitroarenes and quinolines using NaBH4 or H2, as reductants. TEM analyses showed that in all cases the pristine Pd(II) species were reduced in situ to Pd(0), which formed metal nanoparticles (NPs, the real active species). The dependence of their average size (2-10 nm) and morphology on different parameters (temperature, reducing agent, presence of a phase transfer agent) is discussed. TEM and micro-IR analyses showed that the polymeric support retained its porosity and stability for several catalytic cycles in all reactions and Pd NPs did not aggregate after reuse. The metal nanoparticle distribution throughout the polymer matrix after several recycles provided precious information about the catalytic mechanism, which was truly heterogeneous in the hydrogenation reactions and of the so-called "release and catch" type in the Suzuki coupling.

Long-term durability of discarded cork-based composites obtained by geopolymerization.

Geopolymers are amorphous aluminosilicate inorganic polymers synthesized by alkaline activation characterized by a lower carbon footprint, greater durability, and excellent mechanical properties compared to traditional concrete, making them promising building materials for sustainable construction. To develop sustainable lightweight geopolymer-based building materials useful as fire resistant thermal insulation materials, we added 5 and 10 wt% of discarded cork dust, a readily available industrial by-product, to metakaolin before and after the alkaline activation with sodium hydroxide 8 M and sodium silicate solutions. We followed the chemical, microstructural, antibacterial, and physical properties of the resulting composites for up to 90 days in order to monitor their long-term durability. The presence of cork does not interfere with the geopolymerization process and in fact reduces the density of the composites to values around 2.5 g/cm3, especially when added after alkaline activation. The composites resulted in chemically stable matrices (less than 10 ppm of cations release) and filler (no hazardous compounds released) with a bacterial viability of around 80%. This study provides valuable insights into the tailoring of discarded cork-based composites obtained by geopolymerization with a porosity between 32 and 48% and a mechanical resistance to compression from 15 to 5 MPa, respectively, suggesting their potential as durable interior panels with low environmental impact and desirable performance.

Microwave-assisted melt reaction method for the intercalation of carboxylic acid anions into layered double hydroxides.

Carboxylic acid anions intercalated layered double hydroxides are currently gaining increasing interest due to their potential applications in pharmaceutical field for controlled drug release in novel tunable drug delivery systems. In this work different aliphatic carboxylic acid anions were intercalated into the interlayers of commercial as well as synthetically prepared layered double hydroxides, through a novel microwave mediated melt reaction approach. The volumetric nature of microwave dielectric heating was exploited in order to rapidly heat the intimate mixture of the lamellar inorganic precursor and the appropriate organic acid, at the melting temperature of the particular mono- or dicarboxylic acid used, reaching the intercalation in approximately two hours treatment.

Evaluation of Microwave Synthesis of Ceramic Pigments Based on In Situ Dielectric Characterization.

The application of microwave technology for efficient and environmentally friendly synthesis of ceramic pigments is a successful and rapidly evolving area of research. However, a clear understanding of the reactions and their relationship with the material absorbance has not been fully achieved. The present study introduces an in situ permittivity characterization technique, which serves as an innovative and precise tool for assessing the microwave synthesis of ceramic pigments. Several processing parameters (atmosphere, the heating rate, raw mixture composition and particle size) were evaluated by studying the permittivity curves as a function of temperature to elucidate their effect on the synthesis temperature and the final pigment quality. The validity of the proposed approach was verified through correlation with other well-known analysis techniques, such as DSC or XRD, providing valuable information about the reaction mechanisms and the optimum conditions for the synthesis process. In particular, changes in permittivity curves were linked, for the first time, to undesired metal oxide reduction at too-high heating rates and could be used to detect pigment synthesis failures and ensure product quality. The proposed dielectric analysis was also found to be a useful tool for optimizing raw material composition for the microwave process, including the use of chromium with lower specific surface area and flux removal.

Entrapment of Acridine Orange in Metakaolin-Based Geopolymer: A Feasibility Study.

Few studies have explored the immobilization of organic macromolecules within the geopolymer matrix, and some have found their chemical instability in the highly alkaline geopolymerization media. The present work reports on the feasibility of encapsulating the potentially toxic acridine orange (AO) dye in a metakaolin based geopolymer while maintaining its structural integrity. The proper structural, chemical, and mechanical stabilities of the final products were ascertained using Fourier-transform infrared (FT-IR) spectroscopy, scanning electron microscopy (SEM), X-ray diffraction (XRD), thermogravimetric (TGA/DTG), and mechanical analyses, whereas the dye integrity and its stability inside the geopolymer were investigated by the UV-Vis analysis. In addition, the antimicrobial activity was investigated. The FT-IR and XRD analyses confirmed the geopolymerization occurrence, whereas the TGA/DTG and mechanical (compressive and flexural) strength revealed that the addition of 0.31% (AO mg/ sodium silicate L) of AO to the fresh paste did not affect the thermal stability and the mechanical properties (above 6 MPa in flexural strength and above 20 MPa for compressive strength) of the hardened product. UV-Vis spectroscopy revealed that the dye did not undergo chemical degradation nor was it released from the geopolymer matrix. The results reported herein provide a useful approach for the safe removal of toxic macromolecules by means of encapsulation within the geopolymer matrix.

Natural iron-aluminosilicate as potential solid precursor for supplementary cementitious materials: A comparative study with other aluminosilicates.

The objective of this study was to investigate the impact of the geographic and climatic conditions on laterites properties and on geopolymerization based-laterite. Four different laterite deposits in the four geographical zones of Cameroon were studied. This included the center, north, south and west corners of Cameroon, having chemical composition of SiO2 + Al2O3 + Fe2O3 = 88.94, 87.6, 89.13 and 78.97%, respectively. The center and south laterites from the black forest, with high pluviometry and relative humidity, show significant amounts of Fe2O3. While the west laterite from grass field - mountainous areas and the north-laterite from plain arid and semi-arid climate still show lower iron concentrations. The IR absorption bands of the different laterites appear between 1007 and 1047 cm-1; characteristic bands of aluminosilicate. The BET (Brunauer-Emmett-Teller) Specific surface area values are comprised in the range of [21.9, 24.1 m2/g] for non-calcined laterite and between [45.6 and 123.5 m2/g] for laterites calcined at 550 °C and 575 °C. The main particle size values are 5.71, 6.37, 7.43 and 8.45 µm for center-laterite, west-laterite, north laterite and south-laterite, respectively. Although, they differ in the degree of laterization, all the laterites present almost total conversion to geopolymers, due to the presence of amorphous kaolinite and reactive goethite. However, the iron content has significant impact on the globular microstructure. The particle size of laterites, their high values of BET surface area and their significant reactivity make them promising substitutes to metakaolin and other supplementary cementitious materials.

Recycling of Waste Corundum Abrasive Powder in MK-Based Geopolymers.

Recycling corundum abrasive powder in metakaolin-based geopolymer formulations is proposed to reduce the amount of waste to be treated or disposed of in landfills, allowing to decrease ecological damage as well as to reduce transport costs for removal. The addition of waste corundum, as an important source of Al2O3, has proved to increase the slight ionic conductivity of the leachate solution obtained after immersion in water of samples at 28 d of curing at room temperature. With the same curing conditions, the geopolymerization process has not been disturbed as evidenced by the FT-IR peak shift and XRD patterns. It was recorded a decrease in resistance to compression of the consolidated geopolymers of about 5% with 10 wt% addition and of about 77% with the addition of 20 wt% of waste corundum. In any case, the waste abrasive powder does not release heavy metals when added to a geopolymeric formulation based on MK, NaOH, and Na-silicate, and does not show relevant antibacterial properties, indicating the formation of a stable and safe final product with a ceramic-like appearance.

Environmental and Biological Impact of Fly Ash and Metakaolin-Based Alkali-Activated Foams Obtained at 70°C and Fired at 1,000°C.

Alkali-activated foams (AAFs) are inorganic porous materials that can be obtained at temperatures well below 100°C with the use of inorganic wastes as aluminosilicate precursors. In this case, fly ash derived from a Slovenian power plant has been investigated. Despite the environmental benefits per se, due to saving of energy and virgin materials, when using waste materials, it is of extreme importance to also evaluate the potential leaching of heavy metal cations from the alkali-activated foams. This article presents an environmental study of a porous geopolymer derived from this particular fly ash, with respect to the leachability of potentially hazardous elements, its environmental toxicity as determined by biological testing, and the environmental impact of its production. In particular, attention was focused to investigate whether or not 1,000°C-fired alkali-activated fly ash and metakaolin-based foams, cured at 70°C, are environmentally friendlier options compared to unfired ones, and attempts to explain the rationale of the results were done. Eventually, the firing process at 1,000°C, apart from improving technical performance, could reinforce heavy metal cation entrapment within the aluminosilicate matrix. Since technical performance was also modified by addition of different types of activators (K-based or Na-based), as well as by partial replacement of fly ash with metakaolin, a life cycle assessment (LCA) analysis was performed to quantify the effect of these additions and processes (curing at 70°C and firing at 1,000°C) in terms of global warming potential. Selected samples were also evaluated in terms of leaching of potentially deleterious elements as well as for the immobilization effect of firing. The leaching test indicated that none of the alkali-activated material is classified as hazardous, not even the as-received fly ash as component of new AAF. All of the alkali-activated foams do meet the requirements for an inertness. The highest impact on bacterial colonies was found in samples that did not undergo firing procedures, i.e., those that were cured at 70°C, which induced the reduction of bacterial Enterococcus faecalis viability. The second family of bacteria tested, Escherichia coli, appeared more resistant to the alkaline environment (pH = 10-12) generated by the unfired AAMs. Cell viability recorded the lowest value for unfired alkali-activated materials produced from fly ash and K-based activators. Its reticulation is only partial, with the leachate solution appearing to be characterized with the most alkaline pH and with the highest ionic conductivity, i.e., highest number of soluble ions. By LCA, it has been shown that 1) changing K-based activators to Na-based activators increases environmental impact of the alkali-activated foams by 1%-4% in terms of most of the impact categories (taking into account the production stage). However, in terms of impact on abiotic depletion of elements and impact on ozone layer depletion, the increase is relatively more significant (11% and 18%, respectively); 2) replacing some parts of fly ash with metakaolin also results in relatively higher environmental footprint (increase of around 1%-4%, while the impact on abiotic depletion of elements increases by 14%); and finally, 3) firing at 1,000°C contributes significantly to the environmental footprint of alkali-activated foams. In such a case, the footprint increases by around one third, compared to the footprint of alkali-activated foams produced at 70°C. A combination of LCA and leaching/toxicity behavior analysis presents relevant combinations, which can provide information about long-term environmental impact of newly developed waste-based materials.

Towards optimization of mechanical and microstructural performances of Fe-rich laterite geopolymer binders cured at room temperature by varying the activating solution.

In the present study, the performances of the end products prepared using calcined iron-rich laterite at 600 °C (LAT600) with different alkaline solution (AS) to calcined laterite (AS/LAT600) mass ratio (0.45-0.65) were investigated. The effect of AS/LAT600 mass ratio on microstructural and mechanical properties of consolidated geopolymer samples, such as compressive strength, porosity, bulk density, water absorption, mercury intrusion porosimetry (MIP) and scanning electron microscopy (SEM) analysis were determined. Geopolymer made with AS/LAT600 ratio of 0.55 yields the highest compressive strength (54 ± 0.38 MPa) and compact structure. Increasing the AS/LAT600 mass ratio (0.45-0.65) increased the setting time, flowability and decreased the SiO2/Fe2O3 and Al2O3/Fe2O3 molar ratios and compressive strength leading to a weak structure. Both cumulative volume intrusion and cumulative pore area increased from 0.11 to 0.20 mL g-1 and 65.20 to 90.93 m2 g-1, respectively. Such enhancement is linked to changes that occur into the geopolymer network when high alkaline activator/laterite is used. Therefore, further increase of AS/LAT600 mass ratio improved the workability, delaying the polycondensation rate of dissolved calcined laterite and not positively affecting the mechanical strength development. Nevertheless, the performance of the end products could be found application in building engineering.

Characterisation of White Metakaolin-Based Geopolymers Doped with Synthetic Organic Dyes.

Over the years, many materials have been used to restore buildings, paintings, ceramics, and mosaic pieces exhibiting different types of dyes and colour hues. Recently, geopolymers have been used for restoration purposes owing to their high chemical and mechanical resistance. In this work, white metakaolin was used to obtain white geopolymers, cured at 25 and 40 °C, as bulk materials to be coloured with synthetic organic dyes, i.e., bromothymol blue, cresol red, phenolphthalein, and methyl orange. These dyes were added during the fresh paste preparation to obtain dyed geopolymeric solids. Ionic conductivity and pH measurement confirmed the chemical stability of the consolidated materials, while FT-IR analyses were used to follow the geopolymerisation occurrences at different ageing times (from 7 to 56 days). Finally, the colour hues and properties were assessed in the CIELAB colour space before and after immersion in water.

Chemical and Mechanical Properties of Metakaolin-Based Geopolymers with Waste Corundum Powder Resulting from Erosion Testing.

Alkali activated binders, based on an aluminosilicate powder that is activated by an alkaline solution, have been proven to encapsulate a wide number of different wastes, both in the form of liquids and solids. In this study, we investigated the effect that the addition of a spent abrasive powder, mainly composed of corundum grains (RC), had on the mechanical, physical, and chemical properties of metakaolin-based geopolymers. The waste was introduced into the geopolymer matrix as a substitute for metakaolin, or added as a filler to the geopolymeric paste. The 3D cross-linking of the geopolymer structure, with and without the presence of the corundum, was investigated via Fourier transform infrared spectroscopy, X-ray diffraction, and ionic conductivity measurements of the eluate that was produced after 24 h of immersion of the sample in water. The RC powder did not significantly modify the matrix reticulation but increased densification, as observed with scanning electron microscopy, and there was increased resistance to compression by 10 wt% addition of RC, and also when added to the paste as a filler at 20 wt%.

Mine Clay Washing Residues as a Source for Alkali-Activated Binders.

The aim of this paper is to promote the use of mine clay washing residues for the preparation of alkali activated materials (AAMs). In particular, the influence of the calcination temperature of the clayey by-product on the geopolymerization process was investigated in terms of chemical stability and durability in water. The halloysitic clay, a mining by-product, has been used after calcination and mixed with an alkaline solution to form alkali activated binders. Attention was focused on the influence of the clay's calcination treatment (450-500-600 °C) on the geopolymers' microstructure of samples, remaining in the lower limit indicated by the literature for kaolinite or illite calcination. The mixtures of clay and alkali activators (NaOH 8M and Na-silicate) were cured at room temperature for 28 days. The influence of solid to liquid ratio in the mix formulation was also tested in terms of chemical stability measuring the pH and the ionic conductivity of the eluate after 24-h immersion time in water. The results reported values of ionic conductivity higher for samples made with untreated clay or with low temperature of calcination (≥756 mS/m) compared with values of samples made with calcined clay (292 mS/m). This result suggests that without a proper calcination of the as-received clay it was not possible to obtain 25 °C-consolidated AAMs with good chemical stability and dense microstructure. The measures of integrity test, pH, and ionic conductivity in water confirmed that the best sample is made with calcined clay at 600 °C, being similar (53% higher ionic conductivity of the eluate) or equal (integrity test and pH) to values recorded for the metakaolin-based geopolymer considered the reference material. These results were reflected in term of reticulation and morphology of samples through the analysis with scanning electron microscope (SEM) and X-ray diffraction (XRD), which show a dense and homogeneous microstructure predominantly amorphous with minor amounts of quartz, halloysite, and illite crystalline phases. Special attention was dedicated to this by-product to promote its use, given that kaolinite (and metakaolin), as primary mineral product, has a strong impact on the environment. The results obtained led us to consider this halloysite clay very interesting as an aluminosilicate precursor, and extensively deepening its properties and reactivity for the alkaline activation. In fact, the heart of this work is to study the possibility of reusing this by-product of an industrial process to obtain more sustainable high-performance binders.

Efficient Addition of Waste Glass in MK-Based Geopolymers: Microstructure, Antibacterial and Cytotoxicity Investigation.

Reuse of waste glass can significantly decrease the quantity of waste to be treated or disposed of in landfills, allowing to both diminish the ecological damage and to reduce the costs of transportation for removal. Geopolymer mixes with diverse percentages (20, 50 and 60 wt%) and with different grain size ranges (37 µm < diam < 53 µm; 75 µm < diam < 105 µm) of waste glass and the residual part of pure metakaolin were prepared by addition of NaOH and sodium silicate as alkaline activator solutions. The effect of waste glass on the mechanical and microstructure of new geopolymers has been explored in this study. Fourier transform infrared spectroscopy (FTIR) evidenced the reactivity of waste glass in terms of Si-O and Si-O-Al bonds, more evident for the finer waste glass powder. The consolidation of the materials has been established by reduced weight loss in water and decreased pH and ionic conductivity of the eluate after 7, 14 and 28 days of curing at room temperature. The decrease of the mechanical properties with waste glass content was less evident for the finer glassy powders, yet the value of about 4-5 MPa indicates their potential use as non-structural materials. The consolidated final materials were tested for their effects on the microbial growth of Escherichia coli and Enterococcus faecalis after 24 and 48 h, respectively. The samples showed a very limited and absent inhibition zone, for fine and coarse grain size ranges, respectively. Finally, the cytotoxicity tests accomplished the ecological valuation of the final consolidated products.

The Effect of Fibrous Reinforcement on the Polycondensation Degree of Slag-Based Alkali Activated Composites.

Alternative cementitious binders, based on industrial side streams, characterized by a low carbon footprint, are profitably proposed to partially replace Portland cement. Among these alternatives, alkali-activated materials have attracted attention as a promising cementitious binder. In this paper, the chemical stability of the matrix, in fiber-reinforced slag-based alkali-activated composites, was studied, in order to assess any possible effect of the presence of the reinforcement on the chemistry of polycondensation. For this purpose, organic fiber, cellulose, and an inorganic fiber, basalt, were chosen, showing a different behavior in the alkaline media that was used to activate the slag fine powders. The novelty of the paper is the study of consolidation by means of chemical measurements, more than from the mechanical point of view. The evaluation of the chemical behavior of the starting slag in NaOH, indeed, was preparatory to the understanding of the consolidation degree in the alkali-activated composites. The reactivity of alkali-activated composites was studied in water (integrity test, normed leaching test, pH and ionic conductivity), and acids (leaching in acetic acid and HCl attack). The presence of fibers does not favor nor hinder the geopolymerization process, even if an increase in the ionic conductivity in samples containing fibers leads to the hypothesis that samples with fibers are less consolidated, or that fiber dissolution contributes to the conductivity values. The amorphous fraction was enriched in silicon after HCl attack, but the structure was not completely dissolved, and the presence of an amorphous phase is confirmed (C-S-H gel). Basalt fibers partly dissolved in the alkaline environment, leading to the formation of a C-N-A-S-H gel surrounding the fibers. In contrast, cellulose fiber remained stable in both acidic and alkaline conditions.

Microwave-Assisted Vacuum Synthesis of TiO2 Nanocrystalline Powders in One-Pot, One-Step Procedure.

A new method for fast and simple synthesis of crystalline TiO2 nanoparticles with photocatalytic activity was developed by carrying out a classic sol-gel reaction directly under vacuum. The use of microwaves for fast heating of the reaction medium further reduces synthesis times. When the solvent is completely removed by vacuum, the product is obtained in the form of a powder that can be easily redispersed in water to yield a stable nanoparticle suspension, exhibiting a comparable photocatalytic activity with respect to a commercial product. The present methodology can, therefore, be considered a process intensification procedure for the production of nanotitania.

Alkali Activation of Metallurgical Slags: Reactivity, Chemical Behavior, and Environmental Assessment.

Alkali-activated materials (AAMs) represent a promising alternative to conventional building materials and ceramics. Being produced in large amounts as aluminosilicate-rich secondary products, such as slags, they can be utilized for the formulation of AAMs. Slags are partially crystalline metallurgical residues produced during the high temperature separation of metallic and non-metallic materials in the steelmaking processes. In the present study, the electric arc furnace carbon or stainless steel slag (EAF) and secondary metallurgical slag such as ladle furnace basic slag (LS) were used as precursors in an alkali-activation process. EAF slag, with its amorphous fraction of about 56%, presented higher contents of soluble Si and Al species with respect to ladle slag R (35%). However, both are suitable to produce AAM. The leaching behavior shows that all the release values are below the regulation limit. All the bivalent ions (Ba, Cd, Cu, Ni, Pb, and Zn) are well immobilized in a geopolymeric matrix, while amphoteric elements, such as As and Cr, show a slight increase of release with respect to the corresponding slag in alkaline and aqueous environments. In particular, for Sb and As of AAM, release still remains below the regulation limits, while Mo presents an increase of leaching values that slightly exceeds the limit for landfill non-dangerous waste.

FT-IR Study, Thermal Analysis, and Evaluation of the Antibacterial Activity of a MK-Geopolymer Mortar Using Glass Waste as Fine Aggregate.

Food containers made from glass are separately collected from urban solid waste at 76% in most parts of Europe. The cullet glass finds its way to re-melting, while the debris is often disposed of. With this contribution, we suggest an upcycling process where glass debris is simply ground without any washing operation and added to an alkali-activated paste. Metakaolin-based geopolymer mortar added with coarsely ground glass waste as fine aggregate has been prepared via alkali activation with NaOH and Na-silicate. After 7, 14 and 28 days of room temperature curing time, the 3D geopolymer network was investigated by Fourier-transform infrared spectroscopy (FT-IR). Vibrational spectra revealed the geopolymerization occurrences, results which have been supported by both FT-IR deconvoluted spectra and thermogravimetric analysis (TGA). Finally, the antibacterial properties were investigated against both gram-negative (E. coli) and gram-positive (E. faecalis) bacterial strains. The results suggest the ability of the 28 days cured geopolymers to inhibit the growth of the gram-negative bacterium assayed.