Fabrication of zirconium borosilicate glasses using municipal waste ash for radiation shielding applications; optical and structural investigations

Abstract

In this study, three borosilicate glass systems were successfully prepared by using the melting–annealing technique from municipal waste ash and doped with ZrO2 at 0, 0.1, and 0.3 wt.%. The glasses were analyzed by electron dispersive X-ray spectroscopy (EDX), which indicated their rich compositions with various metal ions, and X-ray diffraction analysis (XRD) confirmed their amorphous glassy nature. The effects of gamma radiation at 80 kGy on the optical, physical, structural, and chemical properties of the glasses were evaluated. The optical spectra contained ultraviolet peaks at 260–340 nm and visible peaks at 440–470 nm due to the different valence states of transition metal ions, e.g., Ti4+/Ti3+, Cu2+/Cu+, Zn2+, Fe3+/Fe2+, and/or Zr4+. The optical band gap energy (Egap) decreased from 2.0 to 1.0 eV and from 2.8 to 1.90 eV for indirect and direct transitions after irradiation, respectively, whereas the linear refractive index (n) increased. Fourier transform-infrared spectroscopy (FTIR) indicated high structural stability against irradiation due to the connected borosilicate network comprising trigonal BO3 and tetrahedral BO4 and SiO4 units. The band at 960 cm−1 in the undoped and 0.1% Zr4+ glasses shifted to 980 cm−1 in 0.3% Zr4+ glass because of the different compositions and silica contents of the glasses. Analysis of the chemical durability of the glasses in H2O at 100 °C indicated their high chemical stability before and after irradiation with a weight loss not exceeding 0.05%. BO3, BO4, SiO4, transition metal ions, and ZrO2 all contributed to the compact structure of the glasses, and their high stability against irradiation indicates the potential applications of the glasses in radiation shielding.