Synthesis and characterization of L-asparagine stabilised gold nanoparticles: Catalyst for degradation of organic dyes.

Abstract

L-asparagine functionalized gold nanoparticles (Asp-AuNPs), have been synthesized by reducing HAuCl4 in presence of L-asparagine at 70°C for 8h. Asp-AuNPs were characterized by transmission electron microscopy (TEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS); the nanoparticles formed were spherical in shape with average size of 13.5±3.7nm. Synthesized Asp-AuNPs were found to exhibit excellent catalytic properties for the degradation of different organic dyes viz. Rhodamine B (RB), methyl orange (MO), acid red 27 (amaranth) and xylenol orange (XO) in the presence of sodium borohydride (NaBH4). Asp-AuNPs acts as electron relay system and serve as effective catalyst for complete degradation of all the tested dyes. Rate kinetic investigations suggested that catalysed degradation reactions follow pseudo-first order reaction kinetics with rate constant of 0.904min-1, 0.314min-1, 0.228min-1 and 0.1min-1 for RB, MO, amaranth and XO respectively.