Nanostructured Glass-Ceramic Materials from Glass Waste with Antimicrobial Activity.

Modern consumption patterns have led to a surge in waste glass accumulating in municipal landfills, contributing to environmental pollution, especially in countries that do not have well-established recycling standards. While glass itself is 100% recyclable, the logistics and handling involved present significant challenges. Flint and amber-colored glass, often found in high quantities in municipal waste, can serve as valuable sources of raw materials. We propose an affordable route that requires just a thermal treatment of glass waste to obtain glass-based antimicrobial materials. The thermal treatment induces crystallized nanoregions, which are the primary factor responsible for the bactericidal effect of waste glass. As a result, coarse particles of flint waste glass that undergo thermal treatment at 720 °C show superior antimicrobial activity than amber waste glass. Glass-ceramic materials from flint waste glass, obtained by thermal treatment at 720 °C during 2 h, show antimicrobial activity against Escherichia coli after just 30 min of contact time. Laser-induced breakdown spectroscopy (LIBS) was employed to monitor the elemental composition of the glass waste. The obtained glass-ceramic material was structurally characterized by transmission electron microscopy, enabling the confirmation of the presence of nanocrystals embedded within the glass matrix.

Qualitative and Semiquantitative Determination of the Atomic and Molecular Tungsten Distributions in Hybrid Hydroxyurethanes-Poly(dimethylsiloxane) Films Containing Phosphotungstates ([PW12O40]3-).

In this study, hybrid poly(dimethylsiloxane)-derived hydroxyurethanes films (PDMSUr-PWA) containing phosphotungstic acid (H3PW12O40/PWA) were characterized using field emission gun scanning electron microscopy (FEG-SEM), in attenuated total reflectance Fourier transform mid-infrared mode (ATR FT-MIR), and analyzed using synchrotron radiation micro-X-ray fluorescence (SR-µXRF), synchrotron radiation grazing incidence X-ray fluorescence (SR-GIXRF), laser-induced breakdown spectroscopy (LIBS), and instrumental neutron activation analysis (NAA) in order to correlate the distribution patterns of tungsten and properties of PDMSUr-PWA films. PDMS constitute elastomers with good mechanical, thermal, and chemical (hydrophobicity/non-hygroscopy) resistance. Currently, products based on urethanes (e.g., polyurethanes) are widely used in many applications as plastics, fiber-reinforced polymers, high-performance adhesives, corrosion-resistant coatings, photochromic films, among others. The possibility to combine inorganic and organic components can produce a hybrid material with unique properties. PWA has an important role as agent against the corrosion of steel surfaces in different media, besides exhibiting amazing catalytic and photochromic properties in these films. PWA kept its structure inside of these hybrid films through interactions between the organic matrix of PDMSUr and silanol from the inorganic part (organically modified silica), as was shown using ATR FT-MIR spectra. The FEG-SEM/SR-µXRF/wide-angle X-ray scattering (WAXS)/X-ray diffraction (XRD)/energy dispersive X-ray results proved the presence of PWA in the composition of domains of PDMSUr-PWA films. At PWA concentrations higher than 50 wt%/wt, tungsten segregation across the thickness is predominant, while that at PWA concentrations lower than 35 wt%/wt, tungsten segregation at surface is predominant. Inhomogeneities in the tungsten distribution patterns (at micrometric and millimetric level) may play an important role in the mechanical properties of these films (elastic modulus and hardness).