Green synthesis of Fe3O4@SiO2-Ag magnetic nanocatalyst using safflower extract and its application as recoverable catalyst for reduction of dye pollutants in water

This paper reports the green and in situ preparation of Fe3O4@SiO2-Ag magnetic nanocatalyst synthesized using safflower (Carthamus tinctorius L.) flower extract without the addition of any stabilizers or surfactants. The catalytic performance of the resulting nanocatalyst was examined for the reduction of 4-nitrophenol (4-NP), methylene blue (MB) and methyl orange (MO) in an environment-friendly medium at room temperature. The main factors such as pH, temperature and amount of catalyst influencing the nanocatalyst performance were studied. The apparent rate constants for 4-NP, MO and MB reduction were calculated, being 0.756min(-1), 0.064s(-1) and 0.09s(-1), respectively. The catalyst was recovered using an external magnet and reused several times with negligible loss of catalytic activity. The as-synthesized nanoparticles were characterized using powder X-ray diffraction, transmission electron microscopy, UV-visible, Fourier transform infrared and inductively coupled plasma atomic emission spectroscopies, dynamic light scattering and vibrating sample magnetometry.