Biosynthesis of au nanoparticles by a marine bacterium and enhancing their catalytic activity through metal ions and metal oxides.

Abstract

The authors report that a marine Shewanella sp. CNZ-1 is capable of producing Au NPs under various conditions. Results showed that initial concentration of Au(III), pH values and electron donors affected nucleation of Au NPs by CNZ-1, resulting in different apparent color of the as-obtained bio-Au NPs, which were further characterized by UV-Vis, TEM, XRD, and XPS analyses. Mechanism studies revealed that Au(III) was first reduced to Au(I) and eventually reduced to EPS-coated Au0 NPs. FTIR and FEEM analyses revealed that some amides and humic acid-like matters were involved in the production of bio-Au NPs through CNZ-1 cells. In addition, the authors also found that the catalytic activity of bio-Au NPs for 4-nitrophenol (4-NP) reduction could be enhanced by various metal ions (Ca2+ , Cu2+ , Co2+ , Fe2+ , Fe3+ , Ni2+ , Sr2+ , and Cr3+ ) and metal oxides (Fe3 O4 , Al2 O3 , and SiO2 ), which is beneficial for their further practical application. The maximum zero-order rate constant k 1 and first-order rate constant k2 of all metal ions/oxides supplemented systems can reach 99.65 mg/(L. min) and 2.419 min-1 , which are 11.3- and 12.6-fold higher than that of control systems, respectively. © 2018 American Institute of Chemical Engineers Biotechnol. Prog., 35: e2727, 2019.