Biosynthesis of SnO2 Nanoparticles Using Bacterium Erwinia herbicola and Their Photocatalytic Activity for Degradation of Dyes

Tetragonal SnO 2 nanoparticles (15–40 nm) were synthesized according to a green biological synthesis technique using Gram-negative bacteria Erwinia herbicola followed by an annealing treatment over 425 K. The SnO 2 nanoparticles were characterized by dynamic light scattering (DLS), transmission electron microscopy (TEM), X-ray diffraction spectroscopy (XRD), and scanning electron microscopy with energy dispersive X-ray (SEM-EDX). The zeta potential of biosynthesized SnO 2 nanoparticles was 7.53 mV. A biosynthesis mechanism for SnO 2 nanoparticles was also proposed. In the biosynthesis, the bacterial protein and biomolecules served as the template for reduction and stabilization of SnO 2 nanoparticles. These biomolecules also helped in controlling SnO 2 nanoparticle size and aggregation. The SnO 2 nanoparticles exhibited excellent photocatalytic activity for photodegradation of organic dyes such as methylene blue, methyl orange, and erichrome black T. Approximately 93.3, 97.8, and 94.0% degradations of methylene blue, erichrome black T, and methyl orange were observed with biosynthesized SnO 2 nanoparticles in the photocatalytic degradation process, respectively.