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

L-asparagine functionalized gold nanoparticles (Asp-AuNPs), have been synthesized by reducing HAuCl₄ in presence of L-asparagine at 70 °C for 8 h. 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 ± 3.7 nm. 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 0.904 min^-1, 0.314 min^-1, 0.228 min^-1 and 0.1 min^-1 for RB, MO, amaranth and XO respectively.