Comparative Efficacy of Biogenic Silver Nanoparticles Synthesized by Pseudochrobactrum spp. C5 and Chemically Synthesized Silver Nanoparticles for Catalytic Degradation of Methylene Blue and 4-Nitrophenol Dyes

In this study, a novel bacterial strain, Pseudochrobactrum spp. C5, was isolated from a wastewater sample and characterized for synthesis of the silver nanoparticles (Ag-NPs). The physicochemical and catalytic properties of biogenic Ag-NPs synthesized by involving the strain C5 were compared with the Ag-NPs synthesized by a chemical reaction. The both types of Ag-NPs were characterized for optical properties by UV-visible spectroscopy and fourier-transform infrared spectroscopy (FT-IR), whereas, the morphological, structural, chemical and electronic state properties were evaluated by field emission scanning electron microscope (FESEM), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). These analyses indicated that biogenic Ag-NPs were nano-rod shaped particles ranging from 100–200 nm in size, whereas the chemical Ag-NPs were agglomerated flower shaped structures ranging from 120–300 nm in size. Both types of Ag-NPs were observed to have negative zeta potential values with −27.43 mV and −25.45 mV zeta potential for biogenic and chemically synthesized Ag-NPs. The comparison of both types of Ag-NPs revealed the presence of relatively higher metallic silver (Ag^°) contents, larger available surface for pollutant’s contact and larger distribution of particles in biogenic Ag-NPs as compared to chemically synthesized Ag-NPs, which served for higher catalytic activity. The biogenic Ag-NPs exhibited significantly higher photocatalytic activity for degradation of methylene blue and 4-nitrophenol dyes as compared with that of chemically synthesized Ag-NPs. The findings of this study suggest that the biological Ag-NPs synthesized by Pseudochrobactrum spp. C5 might serve as a potential green solution for treatment of dyes loaded textile wastewaters.