Recycling potential of cathode ray tubes (CRTs) waste glasses based on Bi2O3 addition strategies

Abstract

Cathode-ray tubes (CRTs) from computer monitors and television sets are considered as one of the main sources of waste materials worldwide. Therefore, a new application for such out of use materials is required to solve the relatively huge amount of this waste. In this paper, the popular melt-quench technique was used to synthesis glass samples with the structure: xBi2O3–(100-x) waste CRTs (where x = 0, 10 & 20 wt%) and designated as CRT-Bi0, CRT-Bi10, and CRT-Bi20 accordingly. The physical, structural, optical and radiation absorption competence of the glasses were investigated. The XRD analysis of the glasses reveals an amorphous structure while the mass density increased linearly with the Bi2O3 content of the glasses from 2.86 to 3.08 g/cm3. The optical absorbance of the glasses initially increased and later declined in the visible region as the weight fraction of Bi2O3 increased. The direct optical bandgap Eg values were found to be 3.26, 2.72, and 2.64 eV whereas the indirect Eg values were equal to 3.15, 2.30, and 2.26 eV for CRT-Bi0, CRT-Bi10, and CRT-Bi20, respectively. The gamma-ray interaction parameters of the glasses obtained through FLUKA simulations and XCOM computation showed that mass attenuation falls within the range 0.6991–0.0256, 1.1426–0.0276, 1.5860–0.0301 cm2/g for photon energy range 0.1–10 MeV. Generally, the computed gamma ray interaction quantities show that the gamma ray shielding ability of the CRT-Bi glasses follows the order: CRT-Bi0 < CRT-Bi10 < CRT-Bi20. This order is conserved in the computed interaction cross sections for thermal (25 meV) neutrons. On the other hand the fast neutron removal cross section follows a reverse order with values of 0.0891 cm−1, 0.0867 cm−1, and 0.0850 cm−1 for weight fraction of Bi2O3 from 0 to 20 wt%. The comparison of the gamma–ray attenuation capacity of the CRT-Bi20 with common shielding materials reveals good potential for shielding application. Out of use CRT glasses may thus be recycled for use as radiation shielding glasses as described in this study for gamma radiation protection applications.