Properties of Natural Rubber: Magnetite Decorated with Silver Nanoparticles for Catalytic Degradation of Model Organic Contaminant

Natural rubber–silver-magnetite (NR/Ag–Fe₃O₄) catalyst was successfully prepared by the incorporation of Ag nanoparticles (AgNPs) into NR-coated Fe₃O₄ and its formation was confirmed by X-ray diffraction (XRD), transmission electron microscopy (TEM), Fourier transform infrared (FTIR), scanning electron microscopy coupled with energy dispersive X-ray (SEM/EDX) spectroscopy and atomic absorption spectroscopy (AAS) analyses. The catalytic activity of NR/Ag–Fe₃O₄ was evaluated towards the removal of methyl orange (MO) dye. Different experimental parameters, such as Ag loading, initial dye concentration, and temperature were investigated and discussed in detail. The NR/Ag–Fe₃O₄ catalyst exhibited excellent catalytic activity for the degradation of MO in the presence of potassium borohydride (KBH₄) in aqueous medium. The reaction follows pseudo-first order kinetics. The degradation rate increased with increasing Ag loading and temperature, but decreased with increasing initial dye concentration. The optimized experimental parameters for the degradation process were 2.5 × 10^–5 M and 40 °C. The excellent reusability of NR/Ag–Fe₃O₄ was indicated by the percentage (%) efficiencies of the removal of MO, which were consistently above 95%. Moreover, the lower Fermi energy of the NR/Ag–Fe₃O₄ catalyst than NR/Fe₃O₄ suggested that the presence of AgNPs enhanced the conducting properties of NR/Ag–Fe₃O₄, which led to better electron transfer from KBH₄ to MO molecules and higher degradation rate. The presence of the NR/Ag–Fe₃O₄ catalyst resulted in high mineralization of the MO dye (88.95%), as confirmed by total organic carbon (TOC) analysis.