Magnetite nanoparticle decorated reduced graphene oxide for adsorptive removal of crystal violet and antifungal activities

This work reports the synthesis and application of magnetic rGO/Fe₃O₄ NCs using a pod extract of Dolichos lablab L. as areducing agent. GO was synthesized by a modified Hummers method, however GO was reduced using the plant extract to produce rGO. The as-synthesized rGO/Fe₃O₄ NCs were characterized by UV-vis spectrophotometer, Fourier transform infrared (FT-IR) spectroscopy, FT-Raman spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy supported with energy dispersed X-ray spectroscopy (FESEM-EDX), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The synthesis of magnetic rGO/Fe₃O₄ NCs was confirmed from characterization results of FT-Raman, TEM and VSM. The FT-Raman results showed the D and G bands at 1306.92 cm⁻¹ and 1591 cm⁻¹ due to rGO and a peak at around 589 cm⁻¹ due to Fe₃O₄ NPs that were anchored on rGO sheets; TEM results showed the synthesis of Fe₃O₄ with an average particle size of 8.86 nm anchored on the surface of rGO sheets. The VSM result confirmed the superparamagnetic properties of the rGO/Fe₃O₄ NCs with a saturation magnetization of 42 emu g⁻¹. The adsorption capacity of rGO/Fe₃O₄ NCs towards crystal violet (CV) dye was calculated to be 62 mg g⁻¹. The dye removal behavior fitted well with the Freundlich isotherm and the pseudo-second-order kinetic model implies possible chemisorption. Besides, rGO/Fe₃O₄ NCs showed antifungal activities against Trichophyton mentagrophytes and Candida albicans by agar-well diffusion method with a zone inhibition of 24 mm and 21 mm, respectively. Therefore, rGO/Fe₃O₄ NCs can be used as an excellent adsorbent to remove organic dye pollutants and kill pathogens.