Development of green silicone rubber/waste sludge composites with Bi₂O₃ extracted from olive leaves for radiation...

New fixable composite materials were developed based on silicone rubber reinforced with brine sludge as the main filler, and enhanced with bismuth oxide (Bi₂O₃) prepared from olive leaves as a natural and sustainable resource. For clarity, the samples are coded from SBB0 to SBB5, since (SBB) refers to Silicone Rubber + Brine Sludge + Bi₂O₃, starting with the reference sample (SBB0) without bismuth and going up to (SBB5) with the highest content (35% wt). The shielding properties of these composites were evaluated by measuring the attenuation coefficients such as Linear attenuation coefficient (LAC) and radiation shielding efficiency (RSE%) using photons from a wide range of energies, including low-energy X-rays (15-50 keV) as well as gamma rays (²⁴¹Am at 59.5 keV, ¹³³Ba at 81 and 356 keV, and ¹³⁷Cs at 661.7 keV). The results showed that increasing the Bi₂O₃ content significantly improved the performance of the samples, with SBB4 and SBB5 achieving shielding efficiencies of nearly 100% against X-rays up to 50 keV and over 95% against low-energy gamma rays at only 1 cm thick. This study also showed that increasing the thickness to 5 cm increased the efficiency at high energies, with the SBB5 efficiency reaching approximately 57% at 661.7 keV, compared to less than 10% for the reference sample (SBB0) with a thickness of 1 cm. These results demonstrate that these new composites, made from recycled and environmentally friendly materials, are good and safe compounds for radiation shielding applications in the medical and industrial fields.