Catalytic reduction of methylene blue and Congo red dyes using green synthesized gold nanoparticles capped by salmalia malabarica gum

Abstract Stable gold nanoparticles (AuNPs) were synthesized using salmalia malabarica gum as both reducing and capping agent. It is a simple and eco-friendly green synthesis. The successful formation of AuNPs was confirmed by UV–visible spectroscopy (UV–Vis), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction and transmission electron microscopy (TEM). The synthesized AuNPs were characterized by a peak at 520–535 nm in the UV–Vis spectrum. The X-ray diffraction studies indicated that the resulting AuNPs were highly crystalline with face-centred cubic geometry. TEM studies showed that the average particle size of the synthesized AuNPs was 12 ± 2 nm. FTIR analysis revealed that –OH groups present in the gum matrix might be responsible for the reduction of Au?3 into AuNPs. The synthesized AuNPs exhibited good catalytic properties in the reduction of methylene blue and Congo red.