ABSTRACT
The present study investigated the synthesis of gold nanoparticles (AuNPs) using mangrove plant extract from Avicennia marina as bioreductant for eco-friendly bioremediation of 4-nitrophenol (4-NP). The AuNPs synthesised were confirmed by UV spectrum, transmission electron microscopy (TEM), X-ray diffraction, Fourier transmission infrared spectroscopy (FTIR), dynamic light scattering (DLS), and zeta potential. The AuNPs were found to be spherical in shape with size ranging from 4 to 13â nm, as evident by TEM and DLS. Further, the AuNPs were encapsulated with sodium alginate in the form of gold nano beads and used as heterogeneous catalyst and degrading agent to reduce 4-NP. This reduction in 4-NP into 4-aminophenol was confirmed by UV and FTIR. The aqueous solution of 4-NP peaked its absorbance at 320â nm, and shifted to 400â nm, with an intense yellow colour, appeared due to formation of 4-nitrophenolate ion. After the addition of AuNps, the 4-NP solution became colourless and peaked at 400â nm and reduced to 290â nm corresponding to the formation of 4-aminophenol. Hence, the present work suggested the AuNPs as the potent, eco-friendly bionanocomposite catalyst for bioremediation of 4-NP.
