Bio-Electrochemical Cell Assisted Production of Biogenic Palladium Nanoparticles with Shewanella oneidensis MR-1 Bacteria for the Catalytic Removal of Ofloxacin (OFX) and Doxycycline (DOX) Micropollutants in Pharmaceutical Industry Wastewaters

Abstract

In this study, biogenic-palladium nanoparticles (bio-Pd NPs) with Shewanella oneidensis MR-1 bacteria as a heterostructure bio-electrochemical cell catalyts was examined during catalytic degradation process in the efficient removal of Ofloxacin (OFX) and Doxycycline (DOX) micropollutants from pharmaceutical industry wastewater plant, İzmir, Turkey. Different pH values (3.0, 4.0, 6.0, 7.0, 9.0 and 11.0), increasing micropollutants (OFX and DOX) concentrations (5 mg/l, 15 mg/l, 30 mg/l and 45 mg/l), increasing Bio-Pd NPs concentrations (5 mg/l, 10 mg/l, 20 mg/l, 30 mg/l, 40 mg/l and 60 mg/l), different Bio-Pd NPs/cell dry weight (CDW) mass ratios (5/5, 6/4, 7/3, 8/2, 9/1, 1/9, 2/8, 3/7 and 4/6), increasing recycle times (1., 2., 3., 4., 5., 6. and 7.) was operated during catalytic degradation process in the efficient removals of OFX and DOX micropollutants in pharmaceutical industry wastewater. The characteristics of the synthesized NPs were assessed using Diffuse reflectance UV-Vis spectra (DRS), Energy-dispersive X-ray (EDX), Field emission scanning electron microscopy (FESEM), Fourier transform infrared spectroscopy (FTIR), Inductively coupled plasma mass spectrometry (ICP-MS), Transmission Electron Microscopy (TEM), X-Ray Diffraction (XRD) and X-Ray Photoelectron Spectroscopy (XPS) analyses, respectively. The catalytic activity was first assessed by the degradation of methyl orange. The Bio-NPs showing the highest catalytic activity were selected for the removal of micropollutants (OFX and DOX) from secondary treated municipal wastewater. The catalytic degradation mechanisms of bio-Pd NPs with Shewanella oneidensis MR-1 bacteria as a heterostructure bio-electrochemical cell catalysts and the reaction kinetics of OFX and DOX micropollutants were evaluated in pharmaceutical industry wastewater during catalytic degradation process. ANOVA statistical analysis was used for all experimental samples. The maximum 99% OFX removal efficiency was obtained catalytic removals with bio-electrochemical cell assisted production of bio-Pd NPs with Shewanella oneidensis MR-1 bacteria bio-electrochemical cell catalyts in pharmaceutical industry wastewater, at 30 mg/l OFX concentration, 40 mg/l Bio-Pd NPs concentration, Bio-Pd NPs/CDW mass ratio=6/4, after 24 h catalytic degradation time, at pH=6.0, at 25oC, respectively. The maximum 99% DOX removal efficiency was observed catalytic removals with bio-electrochemical cell assisted production of bio-Pd NPs with Shewanella oneidensis MR-1 bacteria bio-electrochemical cell catalyts in pharmaceutical industry wastewater, at 30 mg/l DOX concentration, 40 mg/l Bio-Pd NPs concentration, Bio-Pd NPs/CDW mass ratio=6/4, after 24 h catalytic degradation time, at pH=9.0, at 25oC, respectively. Finally, the combination of a simple, easy operation preparation process, excellent performance and cost effective, makes this Bio-Pd NPs with Shewanella oneidensis MR-1 bacteria bio-electrochemical cell catalyts a promising option during catalytic degradation process in pharmaceutical industry wastewater treatment.