Photocatalytic Degradation of Safranin ‎Dye from Aqueous Solution Using Nickel ‎Nanoparticles Synthesized by Plant ‎Leaves

   In this paper, a facile and eco-friendly method for the preparation of Ni nanoparticles (Ni NPs) has been described based on the bioreduction of aqueous Ni(II) precursors with Phlomis cancellata Bunge extract. UV-visible spectrum of the aqueous medium containing Ni nanoparticles showed a peak of 390 nm. Since the experimental conditions of this procedure play vital roles in the synthesis rate of the NPs, a response surface methodology using the central composite design was employed for testing the reaction variables. The individual and interactive effects of process variables (temperature, time, concentration of Ni(NO3)2 and pH) upon extracellular biological synthesis of Ni NPs by Phlomis cancellata Bunge were studied. The statistical and perturbation plot analysis suggest that a reaction temperature of 90 °C, duration of 30 min., pH of 9.5 and concentration of 26 mM of Ni(NO3)2 would produce the highest amount of nanoparticles. The NPs were characterized by Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), UV-Visible, and Infrared spectroscopy (IR). The SEM image of Ni NPs showed that the particle shape varied from spherical to polyhedral and ranged between 15 to 25 nm in size. These Ni NPs were studied for their potential role in photocatalytic degradation of safranin dye under solar light irradiation. At optimized conditions, up to 90% safranin dye degradation was achieved.