4-Np Synthesis Lab Report

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A spontaneous, one-pot strategy for the room temperature biosynthesis of gold nanoparticles (AuNPs) using Cocos Nucifera Linn (coconut palm) coir extract is described. The formation of AuNPs was observed within 30s of reaction time between the metal precursor and coir extract. The bioextract acted as both reducing agent and a stabilizer. The influence of various experimental parameters such as % volume fraction of coir extract, concentration of metal precursor, contact time and solution pH on the formation of AuNPs was evaluated to determine the optimum conditions for synthesis. As synthesized AuNPs were characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray analysis
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In the present studies, we have made an attempt to investigate the catalytic activity of as synthesized AuNPs for a model reaction of reduction of 4-NP to 4-AP in the presence of sodium borohydride. The reaction was analyzed by measuring the absorbance of the reaction mixture in the wavelength range of 200-700 nm for fixed time intervals (Fig.8a-b). Initially, the absorption spectra of 4-NP (0.05 mM) showed the absorption peak at 317 nm, which upon addition of excess NaBH4 (15 mM) shifted to longer wavelength at 400 nm due to the formation of 4-nitrophenolate anion under basic conditions. This was also observed by a quick change in the solution color to bright yellow after addition of NaBH4 to 4-NP. Further, the addition of AuNPs to the reaction mixture resulted in bleaching of the yellow color of the solution with time, which leads to decrease in the absorption intensity of the peak at 400 nm along with appearance of a new peak at 300 nm corresponding to the formation of 4-AP. The kinetics of the reduction was followed by monitoring the absorbance spectrum of the reaction mixture for 30 min (Fig.8b). The reduction reaction was completed in 10 min at room temperature with associated color change of the solution from bright yellow to

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