Use of Cyclea peltata mediated gold nanospheres for adsorptive degradation of methyl green dye

Abstract

In this study, gold nanospheres were synthesized due to catalytic reduction of gold ions by phytochemicals of Cyclea peltata leaf extract (CPAuNPs) in 5 h and subsequently used for removal of methyl green (MG) dye. CPAuNPs were characterized by UV–Visible spectrophotometry, scanning electron microscopy (SEM), energy-dispersive X ray spectroscopy (EDAX), Fourier Transformed Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD) and BET analysis. CPAuNPs were spherical, of size 25.73–41.69 nm with SPR peak at 543 nm. CPAuNPs were crystalline in nature and could adsorb 86.02 ± 0.12 % of 50 mg/L MG post one factor at a time analysis. Adsorption followed pseudo-second-order kinetics (k1 = 4.43E−03 g/mg.h), was observed as multilayer chemisorption as the equilibrium data best fitted Freundlich isotherm (R2 = 0.856). Upon interaction of MG by CPAuNPs, hydroxylation of MG lead to formation of crystal violet by attack of N-ethyl N N-Dimethyl ammonium group by hydroxide ions, as evident from LCMS chromatograms.